diff --git a/Cargo.lock b/Cargo.lock
index 6d3d344a060757..0d9b565425972b 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -9286,7 +9286,6 @@ version = "3.1.0"
 dependencies = [
  "bincode",
  "log",
- "qualifier_attr",
  "solana-account",
  "solana-bincode",
  "solana-bpf-loader-program",
@@ -11417,7 +11416,6 @@ dependencies = [
  "futures 0.3.31",
  "log",
  "lru",
- "qualifier_attr",
  "quinn",
  "rustls 0.23.32",
  "solana-cli-config",
diff --git a/Cargo.toml b/Cargo.toml
index 8f0f43b06970ce..e23dad5c899e11 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -175,23 +175,23 @@ used_underscore_binding = "deny"
 [workspace.dependencies]
 Inflector = "0.11.4"
 aes-gcm-siv = "0.11.1"
-agave-banking-stage-ingress-types = { path = "banking-stage-ingress-types", version = "=3.1.0" }
+agave-banking-stage-ingress-types = { path = "banking-stage-ingress-types", version = "=3.1.0", features = ["agave-unstable-api"] }
 agave-cargo-registry = { path = "cargo-registry", version = "=3.1.0" }
-agave-feature-set = { path = "feature-set", version = "=3.1.0" }
-agave-geyser-plugin-interface = { path = "geyser-plugin-interface", version = "=3.1.0" }
-agave-io-uring = { path = "io-uring", version = "=3.1.0" }
-agave-precompiles = { path = "precompiles", version = "=3.1.0" }
-agave-reserved-account-keys = { path = "reserved-account-keys", version = "=3.1.0" }
-agave-scheduler-bindings = { path = "scheduler-bindings", version = "=3.1.0" }
-agave-scheduling-utils = { path = "scheduling-utils", version = "=3.1.0" }
-agave-snapshots = { path = "snapshots", version = "=3.1.0" }
-agave-syscalls = { path = "syscalls", version = "=3.1.0" }
-agave-thread-manager = { path = "thread-manager", version = "=3.1.0" }
-agave-transaction-view = { path = "transaction-view", version = "=3.1.0" }
-agave-verified-packet-receiver = { path = "verified-packet-receiver", version = "=3.1.0" }
-agave-votor = { path = "votor", version = "=3.1.0" }
-agave-votor-messages = { path = "votor-messages", version = "=3.1.0" }
-agave-xdp = { path = "xdp", version = "=3.1.0" }
+agave-feature-set = { path = "feature-set", version = "=3.1.0", features = ["agave-unstable-api"] }
+agave-geyser-plugin-interface = { path = "geyser-plugin-interface", version = "=3.1.0", features = ["agave-unstable-api"] }
+agave-io-uring = { path = "io-uring", version = "=3.1.0", features = ["agave-unstable-api"] }
+agave-precompiles = { path = "precompiles", version = "=3.1.0", features = ["agave-unstable-api"] }
+agave-reserved-account-keys = { path = "reserved-account-keys", version = "=3.1.0", features = ["agave-unstable-api"] }
+agave-scheduler-bindings = { path = "scheduler-bindings", version = "=3.1.0", features = ["agave-unstable-api"] }
+agave-scheduling-utils = { path = "scheduling-utils", version = "=3.1.0", features = ["agave-unstable-api"] }
+agave-snapshots = { path = "snapshots", version = "=3.1.0", features = ["agave-unstable-api"] }
+agave-syscalls = { path = "syscalls", version = "=3.1.0", features = ["agave-unstable-api"] }
+agave-thread-manager = { path = "thread-manager", version = "=3.1.0", features = ["agave-unstable-api"] }
+agave-transaction-view = { path = "transaction-view", version = "=3.1.0", features = ["agave-unstable-api"] }
+agave-verified-packet-receiver = { path = "verified-packet-receiver", version = "=3.1.0", features = ["agave-unstable-api"] }
+agave-votor = { path = "votor", version = "=3.1.0", features = ["agave-unstable-api"] }
+agave-votor-messages = { path = "votor-messages", version = "=3.1.0", features = ["agave-unstable-api"] }
+agave-xdp = { path = "xdp", version = "=3.1.0", features = ["agave-unstable-api"] }
 ahash = "0.8.11"
 anyhow = "1.0.100"
 aquamarine = "0.6.0"
@@ -377,71 +377,71 @@ smpl_jwt = "0.7.1"
 socket2 = "0.6.1"
 soketto = "0.7"
 solana-account = "3.1.0"
-solana-account-decoder = { path = "account-decoder", version = "=3.1.0" }
-solana-account-decoder-client-types = { path = "account-decoder-client-types", version = "=3.1.0" }
+solana-account-decoder = { path = "account-decoder", version = "=3.1.0", features = ["agave-unstable-api"] }
+solana-account-decoder-client-types = { path = "account-decoder-client-types", version = "=3.1.0", features = ["agave-unstable-api"] }
 solana-account-info = "3.0.0"
-solana-accounts-db = { path = "accounts-db", version = "=3.1.0" }
+solana-accounts-db = { path = "accounts-db", version = "=3.1.0", features = ["agave-unstable-api"] }
 solana-address = "1.0.0"
 solana-address-lookup-table-interface = "3.0.0"
 solana-atomic-u64 = "3.0.0"
-solana-banks-client = { path = "banks-client", version = "=3.1.0" }
-solana-banks-interface = { path = "banks-interface", version = "=3.1.0" }
-solana-banks-server = { path = "banks-server", version = "=3.1.0" }
+solana-banks-client = { path = "banks-client", version = "=3.1.0", features = ["agave-unstable-api"] }
+solana-banks-interface = { path = "banks-interface", version = "=3.1.0", features = ["agave-unstable-api"] }
+solana-banks-server = { path = "banks-server", version = "=3.1.0", features = ["agave-unstable-api"] }
 solana-bench-tps = { path = "bench-tps", version = "=3.1.0" }
 solana-big-mod-exp = "3.0.0"
 solana-bincode = "3.0.0"
 solana-blake3-hasher = "3.0.0"
-solana-bloom = { path = "bloom", version = "=3.1.0" }
+solana-bloom = { path = "bloom", version = "=3.1.0", features = ["agave-unstable-api"] }
 solana-bls-signatures = { version = "1.0.0", features = ["serde"] }
 solana-bn254 = "3.0.0"
 solana-borsh = "3.0.0"
-solana-bpf-loader-program = { path = "programs/bpf_loader", version = "=3.1.0" }
-solana-bucket-map = { path = "bucket_map", version = "=3.1.0" }
-solana-builtins = { path = "builtins", version = "=3.1.0" }
-solana-builtins-default-costs = { path = "builtins-default-costs", version = "=3.1.0" }
-solana-clap-utils = { path = "clap-utils", version = "=3.1.0" }
-solana-clap-v3-utils = { path = "clap-v3-utils", version = "=3.1.0" }
+solana-bpf-loader-program = { path = "programs/bpf_loader", version = "=3.1.0", features = ["agave-unstable-api"] }
+solana-bucket-map = { path = "bucket_map", version = "=3.1.0", features = ["agave-unstable-api"] }
+solana-builtins = { path = "builtins", version = "=3.1.0", features = ["agave-unstable-api"] }
+solana-builtins-default-costs = { path = "builtins-default-costs", version = "=3.1.0", features = ["agave-unstable-api"] }
+solana-clap-utils = { path = "clap-utils", version = "=3.1.0", features = ["agave-unstable-api"] }
+solana-clap-v3-utils = { path = "clap-v3-utils", version = "=3.1.0", features = ["agave-unstable-api"] }
 solana-cli = { path = "cli", version = "=3.1.0" }
-solana-cli-config = { path = "cli-config", version = "=3.1.0" }
-solana-cli-output = { path = "cli-output", version = "=3.1.0" }
-solana-client = { path = "client", version = "=3.1.0" }
+solana-cli-config = { path = "cli-config", version = "=3.1.0", features = ["agave-unstable-api"] }
+solana-cli-output = { path = "cli-output", version = "=3.1.0", features = ["agave-unstable-api"] }
+solana-client = { path = "client", version = "=3.1.0", features = ["agave-unstable-api"] }
 solana-client-traits = "3.0.0"
 solana-clock = "3.0.0"
 solana-cluster-type = "3.0.0"
 solana-commitment-config = "3.0.0"
-solana-compute-budget = { path = "compute-budget", version = "=3.1.0" }
-solana-compute-budget-instruction = { path = "compute-budget-instruction", version = "=3.1.0" }
+solana-compute-budget = { path = "compute-budget", version = "=3.1.0", features = ["agave-unstable-api"] }
+solana-compute-budget-instruction = { path = "compute-budget-instruction", version = "=3.1.0", features = ["agave-unstable-api"] }
 solana-compute-budget-interface = "3.0.0"
-solana-compute-budget-program = { path = "programs/compute-budget", version = "=3.1.0" }
+solana-compute-budget-program = { path = "programs/compute-budget", version = "=3.1.0", features = ["agave-unstable-api"] }
 solana-config-interface = "2.0.0"
-solana-connection-cache = { path = "connection-cache", version = "=3.1.0", default-features = false }
-solana-core = { path = "core", version = "=3.1.0" }
-solana-cost-model = { path = "cost-model", version = "=3.1.0" }
+solana-connection-cache = { path = "connection-cache", version = "=3.1.0", default-features = false, features = ["agave-unstable-api"] }
+solana-core = { path = "core", version = "=3.1.0", features = ["agave-unstable-api"] }
+solana-cost-model = { path = "cost-model", version = "=3.1.0", features = ["agave-unstable-api"] }
 solana-cpi = "3.0.0"
-solana-curve25519 = { path = "curves/curve25519", version = "=3.1.0" }
+solana-curve25519 = { path = "curves/curve25519", version = "=3.1.0", features = ["agave-unstable-api"] }
 solana-define-syscall = "3.0.0"
 solana-derivation-path = "3.0.0"
-solana-download-utils = { path = "download-utils", version = "=3.1.0" }
+solana-download-utils = { path = "download-utils", version = "=3.1.0", features = ["agave-unstable-api"] }
 solana-ed25519-program = "3.0.0"
-solana-entry = { path = "entry", version = "=3.1.0" }
+solana-entry = { path = "entry", version = "=3.1.0", features = ["agave-unstable-api"] }
 solana-epoch-info = "3.0.0"
 solana-epoch-rewards = "3.0.0"
 solana-epoch-rewards-hasher = "3.0.0"
 solana-epoch-schedule = "3.0.0"
 solana-example-mocks = "3.0.0"
-solana-faucet = { path = "faucet", version = "=3.1.0" }
+solana-faucet = { path = "faucet", version = "=3.1.0", features = ["agave-unstable-api"] }
 solana-feature-gate-interface = "3.0.0"
-solana-fee = { path = "fee", version = "=3.1.0" }
+solana-fee = { path = "fee", version = "=3.1.0", features = ["agave-unstable-api"] }
 solana-fee-calculator = "3.0.0"
 solana-fee-structure = "3.0.0"
 solana-file-download = "3.1.0"
 solana-frozen-abi = "3.0.0"
 solana-frozen-abi-macro = "3.0.0"
-solana-genesis = { path = "genesis", version = "=3.1.0" }
+solana-genesis = { path = "genesis", version = "=3.1.0", features = ["agave-unstable-api"] }
 solana-genesis-config = "3.0.0"
-solana-genesis-utils = { path = "genesis-utils", version = "=3.1.0" }
-solana-geyser-plugin-manager = { path = "geyser-plugin-manager", version = "=3.1.0" }
-solana-gossip = { path = "gossip", version = "=3.1.0" }
+solana-genesis-utils = { path = "genesis-utils", version = "=3.1.0", features = ["agave-unstable-api"] }
+solana-geyser-plugin-manager = { path = "geyser-plugin-manager", version = "=3.1.0", features = ["agave-unstable-api"] }
+solana-gossip = { path = "gossip", version = "=3.1.0", features = ["agave-unstable-api"] }
 solana-hard-forks = "3.0.0"
 solana-hash = "3.0.0"
 solana-inflation = "3.0.0"
@@ -451,57 +451,57 @@ solana-instructions-sysvar = "3.0.0"
 solana-keccak-hasher = "3.0.0"
 solana-keypair = "3.0.1"
 solana-last-restart-slot = "3.0.0"
-solana-lattice-hash = { path = "lattice-hash", version = "=3.1.0" }
-solana-ledger = { path = "ledger", version = "=3.1.0" }
+solana-lattice-hash = { path = "lattice-hash", version = "=3.1.0", features = ["agave-unstable-api"] }
+solana-ledger = { path = "ledger", version = "=3.1.0", features = ["agave-unstable-api"] }
 solana-loader-v2-interface = "3.0.0"
 solana-loader-v3-interface = "6.1.0"
 solana-loader-v4-interface = "3.1.0"
-solana-loader-v4-program = { path = "programs/loader-v4", version = "=3.1.0" }
-solana-local-cluster = { path = "local-cluster", version = "=3.1.0" }
+solana-loader-v4-program = { path = "programs/loader-v4", version = "=3.1.0", features = ["agave-unstable-api"] }
+solana-local-cluster = { path = "local-cluster", version = "=3.1.0", features = ["agave-unstable-api"] }
 solana-logger = "3.0.0"
-solana-measure = { path = "measure", version = "=3.1.0" }
-solana-merkle-tree = { path = "merkle-tree", version = "=3.1.0" }
+solana-measure = { path = "measure", version = "=3.1.0", features = ["agave-unstable-api"] }
+solana-merkle-tree = { path = "merkle-tree", version = "=3.1.0", features = ["agave-unstable-api"] }
 solana-message = "3.0.1"
-solana-metrics = { path = "metrics", version = "=3.1.0" }
+solana-metrics = { path = "metrics", version = "=3.1.0", features = ["agave-unstable-api"] }
 solana-msg = "3.0.0"
 solana-native-token = "3.0.0"
-solana-net-utils = { path = "net-utils", version = "=3.1.0" }
+solana-net-utils = { path = "net-utils", version = "=3.1.0", features = ["agave-unstable-api"] }
 solana-nohash-hasher = "0.2.1"
 solana-nonce = "3.0.0"
 solana-nonce-account = "3.0.0"
-solana-notifier = { path = "notifier", version = "=3.1.0" }
+solana-notifier = { path = "notifier", version = "=3.1.0", features = ["agave-unstable-api"] }
 solana-offchain-message = "3.0.0"
 solana-packet = "3.0.0"
-solana-perf = { path = "perf", version = "=3.1.0" }
-solana-poh = { path = "poh", version = "=3.1.0" }
+solana-perf = { path = "perf", version = "=3.1.0", features = ["agave-unstable-api"] }
+solana-poh = { path = "poh", version = "=3.1.0", features = ["agave-unstable-api"] }
 solana-poh-config = "3.0.0"
-solana-poseidon = { path = "poseidon", version = "=3.1.0" }
+solana-poseidon = { path = "poseidon", version = "=3.1.0", features = ["agave-unstable-api"] }
 solana-precompile-error = "3.0.0"
 solana-presigner = "3.0.0"
 solana-program = { version = "3.0.0", default-features = false }
-solana-program-binaries = { path = "program-binaries", version = "=3.1.0" }
+solana-program-binaries = { path = "program-binaries", version = "=3.1.0", features = ["agave-unstable-api"] }
 solana-program-entrypoint = "3.1.0"
 solana-program-error = "3.0.0"
 solana-program-memory = "3.0.0"
 solana-program-option = "3.0.0"
 solana-program-pack = "3.0.0"
-solana-program-runtime = { path = "program-runtime", version = "=3.1.0" }
-solana-program-test = { path = "program-test", version = "=3.1.0" }
+solana-program-runtime = { path = "program-runtime", version = "=3.1.0", features = ["agave-unstable-api"] }
+solana-program-test = { path = "program-test", version = "=3.1.0", features = ["agave-unstable-api"] }
 solana-pubkey = { version = "3.0.0", default-features = false }
-solana-pubsub-client = { path = "pubsub-client", version = "=3.1.0" }
-solana-quic-client = { path = "quic-client", version = "=3.1.0" }
+solana-pubsub-client = { path = "pubsub-client", version = "=3.1.0", features = ["agave-unstable-api"] }
+solana-quic-client = { path = "quic-client", version = "=3.1.0", features = ["agave-unstable-api"] }
 solana-quic-definitions = "3.0.0"
-solana-rayon-threadlimit = { path = "rayon-threadlimit", version = "=3.1.0" }
-solana-remote-wallet = { path = "remote-wallet", version = "=3.1.0", default-features = false }
+solana-rayon-threadlimit = { path = "rayon-threadlimit", version = "=3.1.0", features = ["agave-unstable-api"] }
+solana-remote-wallet = { path = "remote-wallet", version = "=3.1.0", default-features = false, features = ["agave-unstable-api"] }
 solana-rent = "3.0.0"
 solana-reward-info = "3.0.0"
-solana-rpc = { path = "rpc", version = "=3.1.0" }
-solana-rpc-client = { path = "rpc-client", version = "=3.1.0", default-features = false }
-solana-rpc-client-api = { path = "rpc-client-api", version = "=3.1.0" }
-solana-rpc-client-nonce-utils = { path = "rpc-client-nonce-utils", version = "=3.1.0" }
-solana-rpc-client-types = { path = "rpc-client-types", version = "=3.1.0" }
-solana-runtime = { path = "runtime", version = "=3.1.0" }
-solana-runtime-transaction = { path = "runtime-transaction", version = "=3.1.0" }
+solana-rpc = { path = "rpc", version = "=3.1.0", features = ["agave-unstable-api"] }
+solana-rpc-client = { path = "rpc-client", version = "=3.1.0", default-features = false, features = ["agave-unstable-api"] }
+solana-rpc-client-api = { path = "rpc-client-api", version = "=3.1.0", features = ["agave-unstable-api"] }
+solana-rpc-client-nonce-utils = { path = "rpc-client-nonce-utils", version = "=3.1.0", features = ["agave-unstable-api"] }
+solana-rpc-client-types = { path = "rpc-client-types", version = "=3.1.0", features = ["agave-unstable-api"] }
+solana-runtime = { path = "runtime", version = "=3.1.0", features = ["agave-unstable-api"] }
+solana-runtime-transaction = { path = "runtime-transaction", version = "=3.1.0", features = ["agave-unstable-api"] }
 solana-sanitize = "3.0.1"
 solana-sbpf = { version = "=0.13.0", default-features = false }
 solana-sdk-ids = "3.0.0"
@@ -510,7 +510,7 @@ solana-secp256k1-recover = "3.0.0"
 solana-secp256r1-program = "3.0.0"
 solana-seed-derivable = "3.0.0"
 solana-seed-phrase = "3.0.0"
-solana-send-transaction-service = { path = "send-transaction-service", version = "=3.1.0" }
+solana-send-transaction-service = { path = "send-transaction-service", version = "=3.1.0", features = ["agave-unstable-api"] }
 solana-serde = "3.0.0"
 solana-serde-varint = "3.0.0"
 solana-serialize-utils = "3.1.0"
@@ -524,49 +524,49 @@ solana-slot-hashes = "3.0.0"
 solana-slot-history = "3.0.0"
 solana-stable-layout = "3.0.0"
 solana-stake-interface = { version = "2.0.1" }
-solana-stake-program = { path = "programs/stake", version = "=3.1.0" }
-solana-storage-bigtable = { path = "storage-bigtable", version = "=3.1.0" }
-solana-storage-proto = { path = "storage-proto", version = "=3.1.0" }
-solana-streamer = { path = "streamer", version = "=3.1.0" }
-solana-svm = { path = "svm", version = "=3.1.0" }
-solana-svm-callback = { path = "svm-callback", version = "=3.1.0" }
-solana-svm-feature-set = { path = "svm-feature-set", version = "=3.1.0" }
-solana-svm-log-collector = { path = "svm-log-collector", version = "=3.1.0" }
-solana-svm-measure = { path = "svm-measure", version = "=3.1.0" }
-solana-svm-timings = { path = "svm-timings", version = "=3.1.0" }
-solana-svm-transaction = { path = "svm-transaction", version = "=3.1.0" }
-solana-svm-type-overrides = { path = "svm-type-overrides", version = "=3.1.0" }
+solana-stake-program = { path = "programs/stake", version = "=3.1.0", features = ["agave-unstable-api"] }
+solana-storage-bigtable = { path = "storage-bigtable", version = "=3.1.0", features = ["agave-unstable-api"] }
+solana-storage-proto = { path = "storage-proto", version = "=3.1.0", features = ["agave-unstable-api"] }
+solana-streamer = { path = "streamer", version = "=3.1.0", features = ["agave-unstable-api"] }
+solana-svm = { path = "svm", version = "=3.1.0", features = ["agave-unstable-api"] }
+solana-svm-callback = { path = "svm-callback", version = "=3.1.0", features = ["agave-unstable-api"] }
+solana-svm-feature-set = { path = "svm-feature-set", version = "=3.1.0", features = ["agave-unstable-api"] }
+solana-svm-log-collector = { path = "svm-log-collector", version = "=3.1.0", features = ["agave-unstable-api"] }
+solana-svm-measure = { path = "svm-measure", version = "=3.1.0", features = ["agave-unstable-api"] }
+solana-svm-timings = { path = "svm-timings", version = "=3.1.0", features = ["agave-unstable-api"] }
+solana-svm-transaction = { path = "svm-transaction", version = "=3.1.0", features = ["agave-unstable-api"] }
+solana-svm-type-overrides = { path = "svm-type-overrides", version = "=3.1.0", features = ["agave-unstable-api"] }
 solana-system-interface = "2.0"
-solana-system-program = { path = "programs/system", version = "=3.1.0" }
+solana-system-program = { path = "programs/system", version = "=3.1.0", features = ["agave-unstable-api"] }
 solana-system-transaction = "3.0.0"
 solana-sysvar = "3.0.0"
 solana-sysvar-id = "3.0.0"
 solana-test-validator = { path = "test-validator", version = "=3.1.0" }
 solana-time-utils = "3.0.0"
-solana-tls-utils = { path = "tls-utils", version = "=3.1.0" }
-solana-tps-client = { path = "tps-client", version = "=3.1.0" }
-solana-tpu-client = { path = "tpu-client", version = "=3.1.0", default-features = false }
-solana-tpu-client-next = { path = "tpu-client-next", version = "=3.1.0" }
+solana-tls-utils = { path = "tls-utils", version = "=3.1.0", features = ["agave-unstable-api"] }
+solana-tps-client = { path = "tps-client", version = "=3.1.0", features = ["agave-unstable-api"] }
+solana-tpu-client = { path = "tpu-client", version = "=3.1.0", default-features = false, features = ["agave-unstable-api"] }
+solana-tpu-client-next = { path = "tpu-client-next", version = "=3.1.0", features = ["agave-unstable-api"] }
 solana-transaction = "3.0.1"
-solana-transaction-context = { path = "transaction-context", version = "=3.1.0", features = ["bincode"] }
+solana-transaction-context = { path = "transaction-context", version = "=3.1.0", features = ["agave-unstable-api", "bincode"] }
 solana-transaction-error = "3.0.0"
-solana-transaction-metrics-tracker = { path = "transaction-metrics-tracker", version = "=3.1.0" }
-solana-transaction-status = { path = "transaction-status", version = "=3.1.0" }
-solana-transaction-status-client-types = { path = "transaction-status-client-types", version = "=3.1.0" }
-solana-turbine = { path = "turbine", version = "=3.1.0" }
-solana-udp-client = { path = "udp-client", version = "=3.1.0" }
-solana-unified-scheduler-logic = { path = "unified-scheduler-logic", version = "=3.1.0" }
-solana-unified-scheduler-pool = { path = "unified-scheduler-pool", version = "=3.1.0" }
+solana-transaction-metrics-tracker = { path = "transaction-metrics-tracker", version = "=3.1.0", features = ["agave-unstable-api"] }
+solana-transaction-status = { path = "transaction-status", version = "=3.1.0", features = ["agave-unstable-api"] }
+solana-transaction-status-client-types = { path = "transaction-status-client-types", version = "=3.1.0", features = ["agave-unstable-api"] }
+solana-turbine = { path = "turbine", version = "=3.1.0", features = ["agave-unstable-api"] }
+solana-udp-client = { path = "udp-client", version = "=3.1.0", features = ["agave-unstable-api"] }
+solana-unified-scheduler-logic = { path = "unified-scheduler-logic", version = "=3.1.0", features = ["agave-unstable-api"] }
+solana-unified-scheduler-pool = { path = "unified-scheduler-pool", version = "=3.1.0", features = ["agave-unstable-api"] }
 solana-validator-exit = "3.0.0"
-solana-version = { path = "version", version = "=3.1.0" }
-solana-vote = { path = "vote", version = "=3.1.0" }
+solana-version = { path = "version", version = "=3.1.0", features = ["agave-unstable-api"] }
+solana-vote = { path = "vote", version = "=3.1.0", features = ["agave-unstable-api"] }
 solana-vote-interface = "4.0.3"
-solana-vote-program = { path = "programs/vote", version = "=3.1.0", default-features = false }
-solana-wen-restart = { path = "wen-restart", version = "=3.1.0" }
-solana-zk-elgamal-proof-program = { path = "programs/zk-elgamal-proof", version = "=3.1.0" }
+solana-vote-program = { path = "programs/vote", version = "=3.1.0", default-features = false, features = ["agave-unstable-api"] }
+solana-wen-restart = { path = "wen-restart", version = "=3.1.0", features = ["agave-unstable-api"] }
+solana-zk-elgamal-proof-program = { path = "programs/zk-elgamal-proof", version = "=3.1.0", features = ["agave-unstable-api"] }
 solana-zk-sdk = "4.0.0"
-solana-zk-token-proof-program = { path = "programs/zk-token-proof", version = "=3.1.0" }
-solana-zk-token-sdk = { path = "zk-token-sdk", version = "=3.1.0" }
+solana-zk-token-proof-program = { path = "programs/zk-token-proof", version = "=3.1.0", features = ["agave-unstable-api"] }
+solana-zk-token-sdk = { path = "zk-token-sdk", version = "=3.1.0", features = ["agave-unstable-api"] }
 spl-associated-token-account-interface = "2.0.0"
 spl-generic-token = "2.0.0"
 spl-memo-interface = "2.0.0"
diff --git a/account-decoder-client-types/Cargo.toml b/account-decoder-client-types/Cargo.toml
index 7e348f756358c2..5dc4e3c8f6128e 100644
--- a/account-decoder-client-types/Cargo.toml
+++ b/account-decoder-client-types/Cargo.toml
@@ -15,6 +15,7 @@ all-features = true
 rustdoc-args = ["--cfg=docsrs"]
 
 [features]
+agave-unstable-api = []
 zstd = ["dep:zstd"]
 
 [dependencies]
diff --git a/account-decoder-client-types/src/lib.rs b/account-decoder-client-types/src/lib.rs
index 4d4c1ff8ac3af6..13014d4651ae85 100644
--- a/account-decoder-client-types/src/lib.rs
+++ b/account-decoder-client-types/src/lib.rs
@@ -1,3 +1,12 @@
+#![cfg_attr(
+    not(feature = "agave-unstable-api"),
+    deprecated(
+        since = "3.1.0",
+        note = "This crate has been marked for formal inclusion in the Agave Unstable API. From \
+                v4.0.0 onward, the `agave-unstable-api` crate feature must be specified to \
+                acknowledge use of an interface that may break without warning."
+    )
+)]
 //! Core RPC client types for solana-account-decoder
 #![cfg_attr(docsrs, feature(doc_auto_cfg))]
 #[cfg(feature = "zstd")]
diff --git a/account-decoder/Cargo.toml b/account-decoder/Cargo.toml
index 2eeb2d4636434a..578b5275a8c27b 100644
--- a/account-decoder/Cargo.toml
+++ b/account-decoder/Cargo.toml
@@ -12,6 +12,9 @@ edition = { workspace = true }
 [package.metadata.docs.rs]
 targets = ["x86_64-unknown-linux-gnu"]
 
+[features]
+agave-unstable-api = []
+
 [dependencies]
 Inflector = { workspace = true }
 base64 = { workspace = true }
diff --git a/account-decoder/src/lib.rs b/account-decoder/src/lib.rs
index 92be846e87407b..90ca676ade87ee 100644
--- a/account-decoder/src/lib.rs
+++ b/account-decoder/src/lib.rs
@@ -1,3 +1,12 @@
+#![cfg_attr(
+    not(feature = "agave-unstable-api"),
+    deprecated(
+        since = "3.1.0",
+        note = "This crate has been marked for formal inclusion in the Agave Unstable API. From \
+                v4.0.0 onward, the `agave-unstable-api` crate feature must be specified to \
+                acknowledge use of an interface that may break without warning."
+    )
+)]
 #![allow(clippy::arithmetic_side_effects)]
 
 pub mod parse_account_data;
diff --git a/accounts-db/Cargo.toml b/accounts-db/Cargo.toml
index 630db27042c23e..5c6b5962ffa712 100644
--- a/accounts-db/Cargo.toml
+++ b/accounts-db/Cargo.toml
@@ -17,6 +17,7 @@ crate-type = ["lib"]
 name = "solana_accounts_db"
 
 [features]
+agave-unstable-api = []
 dev-context-only-utils = [
     "dep:qualifier_attr",
     "dep:solana-keypair",
diff --git a/accounts-db/src/lib.rs b/accounts-db/src/lib.rs
index e698bc154514d5..afadd0506711b2 100644
--- a/accounts-db/src/lib.rs
+++ b/accounts-db/src/lib.rs
@@ -1,3 +1,12 @@
+#![cfg_attr(
+    not(feature = "agave-unstable-api"),
+    deprecated(
+        since = "3.1.0",
+        note = "This crate has been marked for formal inclusion in the Agave Unstable API. From \
+                v4.0.0 onward, the `agave-unstable-api` crate feature must be specified to \
+                acknowledge use of an interface that may break without warning."
+    )
+)]
 #![cfg_attr(feature = "frozen-abi", feature(min_specialization))]
 #![allow(clippy::arithmetic_side_effects)]
 
diff --git a/banking-stage-ingress-types/Cargo.toml b/banking-stage-ingress-types/Cargo.toml
index b27ab6d6b7e17a..599876d201d910 100644
--- a/banking-stage-ingress-types/Cargo.toml
+++ b/banking-stage-ingress-types/Cargo.toml
@@ -9,6 +9,9 @@ homepage = { workspace = true }
 license = { workspace = true }
 edition = { workspace = true }
 
+[features]
+agave-unstable-api = []
+
 [dependencies]
 crossbeam-channel = { workspace = true }
 solana-perf = { workspace = true }
diff --git a/banking-stage-ingress-types/src/lib.rs b/banking-stage-ingress-types/src/lib.rs
index 0fcfb6f31ed391..5acb29adcdec61 100644
--- a/banking-stage-ingress-types/src/lib.rs
+++ b/banking-stage-ingress-types/src/lib.rs
@@ -1,3 +1,12 @@
+#![cfg_attr(
+    not(feature = "agave-unstable-api"),
+    deprecated(
+        since = "3.1.0",
+        note = "This crate has been marked for formal inclusion in the Agave Unstable API. From \
+                v4.0.0 onward, the `agave-unstable-api` crate feature must be specified to \
+                acknowledge use of an interface that may break without warning."
+    )
+)]
 use {crossbeam_channel::Receiver, solana_perf::packet::PacketBatch, std::sync::Arc};
 
 pub type BankingPacketBatch = Arc<Vec<PacketBatch>>;
diff --git a/banks-client/Cargo.toml b/banks-client/Cargo.toml
index 9749ef89482ea4..4c840f96cded5b 100644
--- a/banks-client/Cargo.toml
+++ b/banks-client/Cargo.toml
@@ -16,6 +16,9 @@ targets = ["x86_64-unknown-linux-gnu"]
 crate-type = ["lib"]
 name = "solana_banks_client"
 
+[features]
+agave-unstable-api = []
+
 [dependencies]
 borsh = { workspace = true }
 futures = { workspace = true }
diff --git a/banks-client/src/lib.rs b/banks-client/src/lib.rs
index 90432b08544474..e276efde758869 100644
--- a/banks-client/src/lib.rs
+++ b/banks-client/src/lib.rs
@@ -1,3 +1,12 @@
+#![cfg_attr(
+    not(feature = "agave-unstable-api"),
+    deprecated(
+        since = "3.1.0",
+        note = "This crate has been marked for formal inclusion in the Agave Unstable API. From \
+                v4.0.0 onward, the `agave-unstable-api` crate feature must be specified to \
+                acknowledge use of an interface that may break without warning."
+    )
+)]
 //! A client for the ledger state, from the perspective of an arbitrary validator.
 //!
 //! Use start_tcp_client() to create a client and then import BanksClientExt to
diff --git a/banks-interface/Cargo.toml b/banks-interface/Cargo.toml
index fcd56ec76da678..dfb97cf7b90a08 100644
--- a/banks-interface/Cargo.toml
+++ b/banks-interface/Cargo.toml
@@ -16,6 +16,9 @@ targets = ["x86_64-unknown-linux-gnu"]
 crate-type = ["lib"]
 name = "solana_banks_interface"
 
+[features]
+agave-unstable-api = []
+
 [dependencies]
 serde = { workspace = true }
 solana-account = { workspace = true, features = [ "serde" ] }
diff --git a/banks-interface/src/lib.rs b/banks-interface/src/lib.rs
index fb63e58943eef2..354820c6e0ab0c 100644
--- a/banks-interface/src/lib.rs
+++ b/banks-interface/src/lib.rs
@@ -1,3 +1,12 @@
+#![cfg_attr(
+    not(feature = "agave-unstable-api"),
+    deprecated(
+        since = "3.1.0",
+        note = "This crate has been marked for formal inclusion in the Agave Unstable API. From \
+                v4.0.0 onward, the `agave-unstable-api` crate feature must be specified to \
+                acknowledge use of an interface that may break without warning."
+    )
+)]
 #![allow(deprecated)]
 
 use {
diff --git a/banks-server/Cargo.toml b/banks-server/Cargo.toml
index 3cd5fc9ca75a47..c3d826f90caf67 100644
--- a/banks-server/Cargo.toml
+++ b/banks-server/Cargo.toml
@@ -16,6 +16,9 @@ targets = ["x86_64-unknown-linux-gnu"]
 crate-type = ["lib"]
 name = "solana_banks_server"
 
+[features]
+agave-unstable-api = []
+
 [dependencies]
 agave-feature-set = { workspace = true }
 bincode = { workspace = true }
diff --git a/banks-server/src/lib.rs b/banks-server/src/lib.rs
index 2ea4c4460f373c..c2924beb6e120a 100644
--- a/banks-server/src/lib.rs
+++ b/banks-server/src/lib.rs
@@ -1,2 +1,11 @@
+#![cfg_attr(
+    not(feature = "agave-unstable-api"),
+    deprecated(
+        since = "3.1.0",
+        note = "This crate has been marked for formal inclusion in the Agave Unstable API. From \
+                v4.0.0 onward, the `agave-unstable-api` crate feature must be specified to \
+                acknowledge use of an interface that may break without warning."
+    )
+)]
 #![allow(clippy::arithmetic_side_effects)]
 pub mod banks_server;
diff --git a/bloom/Cargo.toml b/bloom/Cargo.toml
index 987eb3e044f7ed..bdac1ce8001714 100644
--- a/bloom/Cargo.toml
+++ b/bloom/Cargo.toml
@@ -17,6 +17,7 @@ crate-type = ["lib"]
 name = "solana_bloom"
 
 [features]
+agave-unstable-api = []
 frozen-abi = [
     "dep:solana-frozen-abi",
     "dep:solana-frozen-abi-macro",
diff --git a/bloom/src/lib.rs b/bloom/src/lib.rs
index 944643883dd978..0f7d4fb3c59eba 100644
--- a/bloom/src/lib.rs
+++ b/bloom/src/lib.rs
@@ -1,3 +1,12 @@
+#![cfg_attr(
+    not(feature = "agave-unstable-api"),
+    deprecated(
+        since = "3.1.0",
+        note = "This crate has been marked for formal inclusion in the Agave Unstable API. From \
+                v4.0.0 onward, the `agave-unstable-api` crate feature must be specified to \
+                acknowledge use of an interface that may break without warning."
+    )
+)]
 #![cfg_attr(feature = "frozen-abi", feature(min_specialization))]
 pub mod bloom;
 
diff --git a/bucket_map/Cargo.toml b/bucket_map/Cargo.toml
index 32d29ebca537d2..8d47515b0ac836 100644
--- a/bucket_map/Cargo.toml
+++ b/bucket_map/Cargo.toml
@@ -14,6 +14,7 @@ crate-type = ["lib"]
 name = "solana_bucket_map"
 
 [features]
+agave-unstable-api = []
 dev-context-only-utils = []
 
 [dependencies]
diff --git a/bucket_map/src/lib.rs b/bucket_map/src/lib.rs
index a08bafe00c2cd8..015f7ea744ffff 100644
--- a/bucket_map/src/lib.rs
+++ b/bucket_map/src/lib.rs
@@ -1,3 +1,12 @@
+#![cfg_attr(
+    not(feature = "agave-unstable-api"),
+    deprecated(
+        since = "3.1.0",
+        note = "This crate has been marked for formal inclusion in the Agave Unstable API. From \
+                v4.0.0 onward, the `agave-unstable-api` crate feature must be specified to \
+                acknowledge use of an interface that may break without warning."
+    )
+)]
 #![allow(clippy::arithmetic_side_effects)]
 mod bucket;
 pub mod bucket_api;
diff --git a/builtins-default-costs/Cargo.toml b/builtins-default-costs/Cargo.toml
index a9716406407c62..d5597d6490c487 100644
--- a/builtins-default-costs/Cargo.toml
+++ b/builtins-default-costs/Cargo.toml
@@ -18,6 +18,7 @@ crate-type = ["lib"]
 name = "solana_builtins_default_costs"
 
 [features]
+agave-unstable-api = []
 frozen-abi = ["dep:solana-frozen-abi", "solana-vote-program/frozen-abi"]
 dev-context-only-utils = ["dep:qualifier_attr"]
 
diff --git a/builtins-default-costs/src/lib.rs b/builtins-default-costs/src/lib.rs
index fc74bc0c1f4836..0a0cb45cf48e92 100644
--- a/builtins-default-costs/src/lib.rs
+++ b/builtins-default-costs/src/lib.rs
@@ -1,3 +1,12 @@
+#![cfg_attr(
+    not(feature = "agave-unstable-api"),
+    deprecated(
+        since = "3.1.0",
+        note = "This crate has been marked for formal inclusion in the Agave Unstable API. From \
+                v4.0.0 onward, the `agave-unstable-api` crate feature must be specified to \
+                acknowledge use of an interface that may break without warning."
+    )
+)]
 #![cfg_attr(feature = "frozen-abi", feature(min_specialization))]
 #![allow(clippy::arithmetic_side_effects)]
 
diff --git a/builtins/Cargo.toml b/builtins/Cargo.toml
index b22a84411a5fdb..e14e1bd2958c0d 100644
--- a/builtins/Cargo.toml
+++ b/builtins/Cargo.toml
@@ -10,6 +10,7 @@ license = { workspace = true }
 edition = { workspace = true }
 
 [features]
+agave-unstable-api = []
 dev-context-only-utils = []
 
 [dependencies]
diff --git a/builtins/src/lib.rs b/builtins/src/lib.rs
index 1aba4655a02f0b..9d7b0624c545e7 100644
--- a/builtins/src/lib.rs
+++ b/builtins/src/lib.rs
@@ -1,3 +1,12 @@
+#![cfg_attr(
+    not(feature = "agave-unstable-api"),
+    deprecated(
+        since = "3.1.0",
+        note = "This crate has been marked for formal inclusion in the Agave Unstable API. From \
+                v4.0.0 onward, the `agave-unstable-api` crate feature must be specified to \
+                acknowledge use of an interface that may break without warning."
+    )
+)]
 //! Solana builtin programs.
 //!
 //! Warning: This crate is not for public consumption. It will change, and
diff --git a/clap-utils/Cargo.toml b/clap-utils/Cargo.toml
index 6b37e196e03e06..a5cbeccbbbe523 100644
--- a/clap-utils/Cargo.toml
+++ b/clap-utils/Cargo.toml
@@ -15,6 +15,9 @@ targets = ["x86_64-unknown-linux-gnu"]
 [lib]
 name = "solana_clap_utils"
 
+[features]
+agave-unstable-api = []
+
 [dependencies]
 chrono = { workspace = true, features = ["default"] }
 clap = "2.33.0"
diff --git a/clap-utils/src/lib.rs b/clap-utils/src/lib.rs
index 58a27b2424401a..f0aa2bc3658675 100644
--- a/clap-utils/src/lib.rs
+++ b/clap-utils/src/lib.rs
@@ -1,3 +1,12 @@
+#![cfg_attr(
+    not(feature = "agave-unstable-api"),
+    deprecated(
+        since = "3.1.0",
+        note = "This crate has been marked for formal inclusion in the Agave Unstable API. From \
+                v4.0.0 onward, the `agave-unstable-api` crate feature must be specified to \
+                acknowledge use of an interface that may break without warning."
+    )
+)]
 use thiserror::Error;
 
 pub struct ArgConstant<'a> {
diff --git a/clap-v3-utils/Cargo.toml b/clap-v3-utils/Cargo.toml
index 2f0ff47d40aa91..820282040b71b6 100644
--- a/clap-v3-utils/Cargo.toml
+++ b/clap-v3-utils/Cargo.toml
@@ -16,6 +16,7 @@ targets = ["x86_64-unknown-linux-gnu"]
 name = "solana_clap_v3_utils"
 
 [features]
+agave-unstable-api = []
 elgamal = ["dep:solana-zk-sdk"]
 
 [dependencies]
diff --git a/clap-v3-utils/src/lib.rs b/clap-v3-utils/src/lib.rs
index c3edf98dc57d20..aaa3f9c1eee513 100644
--- a/clap-v3-utils/src/lib.rs
+++ b/clap-v3-utils/src/lib.rs
@@ -1,3 +1,12 @@
+#![cfg_attr(
+    not(feature = "agave-unstable-api"),
+    deprecated(
+        since = "3.1.0",
+        note = "This crate has been marked for formal inclusion in the Agave Unstable API. From \
+                v4.0.0 onward, the `agave-unstable-api` crate feature must be specified to \
+                acknowledge use of an interface that may break without warning."
+    )
+)]
 use thiserror::Error;
 
 pub struct ArgConstant<'a> {
diff --git a/cli-config/Cargo.toml b/cli-config/Cargo.toml
index afd99bcc3f5770..fec95a467ad569 100644
--- a/cli-config/Cargo.toml
+++ b/cli-config/Cargo.toml
@@ -12,6 +12,9 @@ edition = { workspace = true }
 [package.metadata.docs.rs]
 targets = ["x86_64-unknown-linux-gnu"]
 
+[features]
+agave-unstable-api = []
+
 [dependencies]
 dirs-next = { workspace = true }
 serde = { workspace = true }
diff --git a/cli-config/src/lib.rs b/cli-config/src/lib.rs
index 8b20bd2ee87d9e..4c36c4bf516a05 100644
--- a/cli-config/src/lib.rs
+++ b/cli-config/src/lib.rs
@@ -1,3 +1,12 @@
+#![cfg_attr(
+    not(feature = "agave-unstable-api"),
+    deprecated(
+        since = "3.1.0",
+        note = "This crate has been marked for formal inclusion in the Agave Unstable API. From \
+                v4.0.0 onward, the `agave-unstable-api` crate feature must be specified to \
+                acknowledge use of an interface that may break without warning."
+    )
+)]
 //! Loading and saving the Solana CLI configuration file.
 //!
 //! The configuration file used by the Solana CLI includes information about the
diff --git a/cli-output/Cargo.toml b/cli-output/Cargo.toml
index 8954b83b38626c..cedb05a34e82d6 100644
--- a/cli-output/Cargo.toml
+++ b/cli-output/Cargo.toml
@@ -12,6 +12,9 @@ edition = { workspace = true }
 [package.metadata.docs.rs]
 targets = ["x86_64-unknown-linux-gnu"]
 
+[features]
+agave-unstable-api = []
+
 [dependencies]
 Inflector = { workspace = true }
 agave-reserved-account-keys = { workspace = true }
diff --git a/cli-output/src/lib.rs b/cli-output/src/lib.rs
index 5bd3c036f48bf9..d95140100678ea 100644
--- a/cli-output/src/lib.rs
+++ b/cli-output/src/lib.rs
@@ -1,3 +1,12 @@
+#![cfg_attr(
+    not(feature = "agave-unstable-api"),
+    deprecated(
+        since = "3.1.0",
+        note = "This crate has been marked for formal inclusion in the Agave Unstable API. From \
+                v4.0.0 onward, the `agave-unstable-api` crate feature must be specified to \
+                acknowledge use of an interface that may break without warning."
+    )
+)]
 #![allow(clippy::arithmetic_side_effects)]
 mod cli_output;
 pub mod cli_version;
diff --git a/client/Cargo.toml b/client/Cargo.toml
index 6000cd95b3388a..18f0312cd76962 100644
--- a/client/Cargo.toml
+++ b/client/Cargo.toml
@@ -13,6 +13,7 @@ edition = { workspace = true }
 targets = ["x86_64-unknown-linux-gnu"]
 
 [features]
+agave-unstable-api = []
 dev-context-only-utils = []
 
 [dependencies]
diff --git a/client/src/lib.rs b/client/src/lib.rs
index 1dd13906080768..188eb5db5dfe7c 100644
--- a/client/src/lib.rs
+++ b/client/src/lib.rs
@@ -1,3 +1,12 @@
+#![cfg_attr(
+    not(feature = "agave-unstable-api"),
+    deprecated(
+        since = "3.1.0",
+        note = "This crate has been marked for formal inclusion in the Agave Unstable API. From \
+                v4.0.0 onward, the `agave-unstable-api` crate feature must be specified to \
+                acknowledge use of an interface that may break without warning."
+    )
+)]
 #![allow(clippy::arithmetic_side_effects)]
 
 pub mod client_option;
diff --git a/compute-budget-instruction/Cargo.toml b/compute-budget-instruction/Cargo.toml
index 8971b9b619c6bf..78d776d9fa7b96 100644
--- a/compute-budget-instruction/Cargo.toml
+++ b/compute-budget-instruction/Cargo.toml
@@ -17,6 +17,7 @@ crate-type = ["lib"]
 name = "solana_compute_budget_instruction"
 
 [features]
+agave-unstable-api = []
 dev-context-only-utils = []
 
 [dependencies]
diff --git a/compute-budget-instruction/src/lib.rs b/compute-budget-instruction/src/lib.rs
index 032730b9f1bf56..bd4b66ab38d53b 100644
--- a/compute-budget-instruction/src/lib.rs
+++ b/compute-budget-instruction/src/lib.rs
@@ -1,3 +1,12 @@
+#![cfg_attr(
+    not(feature = "agave-unstable-api"),
+    deprecated(
+        since = "3.1.0",
+        note = "This crate has been marked for formal inclusion in the Agave Unstable API. From \
+                v4.0.0 onward, the `agave-unstable-api` crate feature must be specified to \
+                acknowledge use of an interface that may break without warning."
+    )
+)]
 #![allow(clippy::arithmetic_side_effects)]
 
 mod builtin_programs_filter;
diff --git a/compute-budget/Cargo.toml b/compute-budget/Cargo.toml
index 2babd3d921dcfb..fbd9251fbe4e33 100644
--- a/compute-budget/Cargo.toml
+++ b/compute-budget/Cargo.toml
@@ -10,6 +10,7 @@ license = { workspace = true }
 edition = { workspace = true }
 
 [features]
+agave-unstable-api = []
 dev-context-only-utils = [
     "dep:qualifier_attr",
     "solana-program-runtime/dev-context-only-utils",
diff --git a/compute-budget/src/lib.rs b/compute-budget/src/lib.rs
index 64108a0f225183..04513bb30c040b 100644
--- a/compute-budget/src/lib.rs
+++ b/compute-budget/src/lib.rs
@@ -1,3 +1,12 @@
+#![cfg_attr(
+    not(feature = "agave-unstable-api"),
+    deprecated(
+        since = "3.1.0",
+        note = "This crate has been marked for formal inclusion in the Agave Unstable API. From \
+                v4.0.0 onward, the `agave-unstable-api` crate feature must be specified to \
+                acknowledge use of an interface that may break without warning."
+    )
+)]
 //! Solana compute budget types and default configurations.
 #![cfg_attr(feature = "frozen-abi", feature(min_specialization))]
 
diff --git a/connection-cache/Cargo.toml b/connection-cache/Cargo.toml
index c246526e16d559..0106606d20971b 100644
--- a/connection-cache/Cargo.toml
+++ b/connection-cache/Cargo.toml
@@ -9,6 +9,9 @@ homepage = { workspace = true }
 license = { workspace = true }
 edition = { workspace = true }
 
+[features]
+agave-unstable-api = []
+
 [dependencies]
 async-trait = { workspace = true }
 bincode = { workspace = true }
diff --git a/connection-cache/src/lib.rs b/connection-cache/src/lib.rs
index 80314369a6e3e5..ac09b1c4d6c33e 100644
--- a/connection-cache/src/lib.rs
+++ b/connection-cache/src/lib.rs
@@ -1,3 +1,12 @@
+#![cfg_attr(
+    not(feature = "agave-unstable-api"),
+    deprecated(
+        since = "3.1.0",
+        note = "This crate has been marked for formal inclusion in the Agave Unstable API. From \
+                v4.0.0 onward, the `agave-unstable-api` crate feature must be specified to \
+                acknowledge use of an interface that may break without warning."
+    )
+)]
 #![allow(clippy::arithmetic_side_effects)]
 
 pub mod client_connection;
diff --git a/core/Cargo.toml b/core/Cargo.toml
index e978329c6fa826..cb1ddf323ddfbf 100644
--- a/core/Cargo.toml
+++ b/core/Cargo.toml
@@ -13,6 +13,7 @@ edition = { workspace = true }
 targets = ["x86_64-unknown-linux-gnu"]
 
 [features]
+agave-unstable-api = []
 dev-context-only-utils = [
     "solana-perf/dev-context-only-utils",
     "solana-runtime/dev-context-only-utils",
diff --git a/core/src/lib.rs b/core/src/lib.rs
index b30312465f68ca..d542e3e848b586 100644
--- a/core/src/lib.rs
+++ b/core/src/lib.rs
@@ -1,3 +1,12 @@
+#![cfg_attr(
+    not(feature = "agave-unstable-api"),
+    deprecated(
+        since = "3.1.0",
+        note = "This crate has been marked for formal inclusion in the Agave Unstable API. From \
+                v4.0.0 onward, the `agave-unstable-api` crate feature must be specified to \
+                acknowledge use of an interface that may break without warning."
+    )
+)]
 #![cfg_attr(feature = "frozen-abi", feature(min_specialization))]
 #![allow(clippy::arithmetic_side_effects)]
 #![recursion_limit = "2048"]
diff --git a/cost-model/Cargo.toml b/cost-model/Cargo.toml
index ed7856f71f9147..16382ee189dfe0 100644
--- a/cost-model/Cargo.toml
+++ b/cost-model/Cargo.toml
@@ -17,6 +17,7 @@ crate-type = ["lib"]
 name = "solana_cost_model"
 
 [features]
+agave-unstable-api = []
 dev-context-only-utils = [
     "dep:solana-hash",
     "dep:solana-message",
diff --git a/cost-model/src/lib.rs b/cost-model/src/lib.rs
index 872d21106801d3..8daf406942e710 100644
--- a/cost-model/src/lib.rs
+++ b/cost-model/src/lib.rs
@@ -1,3 +1,12 @@
+#![cfg_attr(
+    not(feature = "agave-unstable-api"),
+    deprecated(
+        since = "3.1.0",
+        note = "This crate has been marked for formal inclusion in the Agave Unstable API. From \
+                v4.0.0 onward, the `agave-unstable-api` crate feature must be specified to \
+                acknowledge use of an interface that may break without warning."
+    )
+)]
 #![cfg_attr(feature = "frozen-abi", feature(min_specialization))]
 #![allow(clippy::arithmetic_side_effects)]
 
diff --git a/curves/curve25519/Cargo.toml b/curves/curve25519/Cargo.toml
index 7beb5dc7499bbc..cb6a56be623fc2 100644
--- a/curves/curve25519/Cargo.toml
+++ b/curves/curve25519/Cargo.toml
@@ -9,6 +9,9 @@ homepage = { workspace = true }
 license = { workspace = true }
 edition = { workspace = true }
 
+[features]
+agave-unstable-api = []
+
 [dependencies]
 bytemuck = { workspace = true }
 bytemuck_derive = { workspace = true }
diff --git a/curves/curve25519/src/lib.rs b/curves/curve25519/src/lib.rs
index d0ab9d4709da11..8d10c26d689725 100644
--- a/curves/curve25519/src/lib.rs
+++ b/curves/curve25519/src/lib.rs
@@ -1,3 +1,12 @@
+#![cfg_attr(
+    not(feature = "agave-unstable-api"),
+    deprecated(
+        since = "3.1.0",
+        note = "This crate has been marked for formal inclusion in the Agave Unstable API. From \
+                v4.0.0 onward, the `agave-unstable-api` crate feature must be specified to \
+                acknowledge use of an interface that may break without warning."
+    )
+)]
 #![allow(clippy::arithmetic_side_effects, clippy::op_ref)]
 //! Syscall operations for curve25519
 
diff --git a/download-utils/Cargo.toml b/download-utils/Cargo.toml
index 7f5e194490946c..47b196ba3e16fb 100644
--- a/download-utils/Cargo.toml
+++ b/download-utils/Cargo.toml
@@ -16,6 +16,9 @@ targets = ["x86_64-unknown-linux-gnu"]
 crate-type = ["lib"]
 name = "solana_download_utils"
 
+[features]
+agave-unstable-api = []
+
 [dependencies]
 agave-snapshots = { workspace = true }
 log = { workspace = true }
diff --git a/download-utils/src/lib.rs b/download-utils/src/lib.rs
index 4ca89e1241bd5d..9e4d97b6797708 100644
--- a/download-utils/src/lib.rs
+++ b/download-utils/src/lib.rs
@@ -1,3 +1,12 @@
+#![cfg_attr(
+    not(feature = "agave-unstable-api"),
+    deprecated(
+        since = "3.1.0",
+        note = "This crate has been marked for formal inclusion in the Agave Unstable API. From \
+                v4.0.0 onward, the `agave-unstable-api` crate feature must be specified to \
+                acknowledge use of an interface that may break without warning."
+    )
+)]
 pub use solana_file_download::DownloadProgressRecord;
 use {
     agave_snapshots::{ArchiveFormat, ZstdConfig},
diff --git a/entry/Cargo.toml b/entry/Cargo.toml
index 67ff51310ef3fb..26bf0574ed9d20 100644
--- a/entry/Cargo.toml
+++ b/entry/Cargo.toml
@@ -17,6 +17,7 @@ crate-type = ["lib"]
 name = "solana_entry"
 
 [features]
+agave-unstable-api = []
 dev-context-only-utils = []
 
 [dependencies]
diff --git a/entry/src/lib.rs b/entry/src/lib.rs
index 3d114242404e31..af233d12d968f6 100644
--- a/entry/src/lib.rs
+++ b/entry/src/lib.rs
@@ -1,3 +1,12 @@
+#![cfg_attr(
+    not(feature = "agave-unstable-api"),
+    deprecated(
+        since = "3.1.0",
+        note = "This crate has been marked for formal inclusion in the Agave Unstable API. From \
+                v4.0.0 onward, the `agave-unstable-api` crate feature must be specified to \
+                acknowledge use of an interface that may break without warning."
+    )
+)]
 #![allow(clippy::arithmetic_side_effects)]
 pub mod entry;
 pub mod poh;
diff --git a/faucet/Cargo.toml b/faucet/Cargo.toml
index bc67f9ee29daab..0a906e97a0cafe 100644
--- a/faucet/Cargo.toml
+++ b/faucet/Cargo.toml
@@ -21,6 +21,7 @@ name = "solana-faucet"
 path = "src/bin/faucet.rs"
 
 [features]
+agave-unstable-api = []
 dev-context-only-utils = []
 
 [dependencies]
diff --git a/faucet/src/lib.rs b/faucet/src/lib.rs
index 7421799dd2aa00..d7a14c1bee21da 100644
--- a/faucet/src/lib.rs
+++ b/faucet/src/lib.rs
@@ -1,2 +1,11 @@
+#![cfg_attr(
+    not(feature = "agave-unstable-api"),
+    deprecated(
+        since = "3.1.0",
+        note = "This crate has been marked for formal inclusion in the Agave Unstable API. From \
+                v4.0.0 onward, the `agave-unstable-api` crate feature must be specified to \
+                acknowledge use of an interface that may break without warning."
+    )
+)]
 pub mod faucet;
 pub mod faucet_mock;
diff --git a/feature-set/Cargo.toml b/feature-set/Cargo.toml
index 8b29e823d9b602..1c1f20ab14ec3c 100644
--- a/feature-set/Cargo.toml
+++ b/feature-set/Cargo.toml
@@ -10,6 +10,7 @@ edition = { workspace = true }
 readme = false
 
 [features]
+agave-unstable-api = []
 frozen-abi = ["dep:solana-frozen-abi", "dep:solana-frozen-abi-macro"]
 
 [dependencies]
diff --git a/feature-set/src/lib.rs b/feature-set/src/lib.rs
index b525e208bfd8b8..11bc693d7b4acc 100644
--- a/feature-set/src/lib.rs
+++ b/feature-set/src/lib.rs
@@ -1,3 +1,12 @@
+#![cfg_attr(
+    not(feature = "agave-unstable-api"),
+    deprecated(
+        since = "3.1.0",
+        note = "This crate has been marked for formal inclusion in the Agave Unstable API. From \
+                v4.0.0 onward, the `agave-unstable-api` crate feature must be specified to \
+                acknowledge use of an interface that may break without warning."
+    )
+)]
 #![cfg_attr(feature = "frozen-abi", feature(min_specialization))]
 
 use {
diff --git a/fee/Cargo.toml b/fee/Cargo.toml
index 032a9d127ebc48..9f01cce5719f68 100644
--- a/fee/Cargo.toml
+++ b/fee/Cargo.toml
@@ -9,6 +9,9 @@ homepage = { workspace = true }
 license = { workspace = true }
 edition = { workspace = true }
 
+[features]
+agave-unstable-api = []
+
 [dependencies]
 agave-feature-set = { workspace = true }
 solana-fee-structure = { workspace = true }
diff --git a/fee/src/lib.rs b/fee/src/lib.rs
index 43795518f66431..17cb9d44d66d32 100644
--- a/fee/src/lib.rs
+++ b/fee/src/lib.rs
@@ -1,3 +1,12 @@
+#![cfg_attr(
+    not(feature = "agave-unstable-api"),
+    deprecated(
+        since = "3.1.0",
+        note = "This crate has been marked for formal inclusion in the Agave Unstable API. From \
+                v4.0.0 onward, the `agave-unstable-api` crate feature must be specified to \
+                acknowledge use of an interface that may break without warning."
+    )
+)]
 use {
     agave_feature_set::{enable_secp256r1_precompile, FeatureSet},
     solana_fee_structure::FeeDetails,
diff --git a/genesis-utils/Cargo.toml b/genesis-utils/Cargo.toml
index f4040d34136bf0..63210cec4193fd 100644
--- a/genesis-utils/Cargo.toml
+++ b/genesis-utils/Cargo.toml
@@ -16,6 +16,9 @@ targets = ["x86_64-unknown-linux-gnu"]
 crate-type = ["lib"]
 name = "solana_genesis_utils"
 
+[features]
+agave-unstable-api = []
+
 [dependencies]
 log = { workspace = true }
 solana-accounts-db = { workspace = true }
diff --git a/genesis-utils/src/lib.rs b/genesis-utils/src/lib.rs
index 150d8602468ec2..9c179fe73c7a1b 100644
--- a/genesis-utils/src/lib.rs
+++ b/genesis-utils/src/lib.rs
@@ -1,3 +1,12 @@
+#![cfg_attr(
+    not(feature = "agave-unstable-api"),
+    deprecated(
+        since = "3.1.0",
+        note = "This crate has been marked for formal inclusion in the Agave Unstable API. From \
+                v4.0.0 onward, the `agave-unstable-api` crate feature must be specified to \
+                acknowledge use of an interface that may break without warning."
+    )
+)]
 use {
     log::*,
     solana_accounts_db::hardened_unpack::unpack_genesis_archive,
diff --git a/genesis/Cargo.toml b/genesis/Cargo.toml
index b5bdab720b1131..eb9dd816a7695e 100644
--- a/genesis/Cargo.toml
+++ b/genesis/Cargo.toml
@@ -19,6 +19,9 @@ name = "solana_genesis"
 name = "solana-genesis"
 path = "src/main.rs"
 
+[features]
+agave-unstable-api = []
+
 [dependencies]
 agave-feature-set = { workspace = true }
 base64 = { workspace = true }
diff --git a/genesis/src/lib.rs b/genesis/src/lib.rs
index ef54f1660ffb4d..5c6577f619b033 100644
--- a/genesis/src/lib.rs
+++ b/genesis/src/lib.rs
@@ -1,3 +1,12 @@
+#![cfg_attr(
+    not(feature = "agave-unstable-api"),
+    deprecated(
+        since = "3.1.0",
+        note = "This crate has been marked for formal inclusion in the Agave Unstable API. From \
+                v4.0.0 onward, the `agave-unstable-api` crate feature must be specified to \
+                acknowledge use of an interface that may break without warning."
+    )
+)]
 #![allow(clippy::arithmetic_side_effects)]
 pub mod address_generator;
 pub mod genesis_accounts;
diff --git a/geyser-plugin-interface/Cargo.toml b/geyser-plugin-interface/Cargo.toml
index dcd59b815833e4..fe3bee29170261 100644
--- a/geyser-plugin-interface/Cargo.toml
+++ b/geyser-plugin-interface/Cargo.toml
@@ -12,6 +12,9 @@ edition = { workspace = true }
 [package.metadata.docs.rs]
 targets = ["x86_64-unknown-linux-gnu"]
 
+[features]
+agave-unstable-api = []
+
 [dependencies]
 log = { workspace = true, features = ["std"] }
 solana-clock = { workspace = true }
diff --git a/geyser-plugin-interface/src/lib.rs b/geyser-plugin-interface/src/lib.rs
index a6c5cad0e5aed6..21d4f24d87fb6d 100644
--- a/geyser-plugin-interface/src/lib.rs
+++ b/geyser-plugin-interface/src/lib.rs
@@ -1 +1,10 @@
+#![cfg_attr(
+    not(feature = "agave-unstable-api"),
+    deprecated(
+        since = "3.1.0",
+        note = "This crate has been marked for formal inclusion in the Agave Unstable API. From \
+                v4.0.0 onward, the `agave-unstable-api` crate feature must be specified to \
+                acknowledge use of an interface that may break without warning."
+    )
+)]
 pub mod geyser_plugin_interface;
diff --git a/geyser-plugin-manager/Cargo.toml b/geyser-plugin-manager/Cargo.toml
index 17e438af32915a..d720305782ac0a 100644
--- a/geyser-plugin-manager/Cargo.toml
+++ b/geyser-plugin-manager/Cargo.toml
@@ -12,6 +12,9 @@ edition = { workspace = true }
 [package.metadata.docs.rs]
 targets = ["x86_64-unknown-linux-gnu"]
 
+[features]
+agave-unstable-api = []
+
 [dependencies]
 agave-geyser-plugin-interface = { workspace = true }
 bs58 = { workspace = true }
diff --git a/geyser-plugin-manager/src/lib.rs b/geyser-plugin-manager/src/lib.rs
index 2dd1a8f5d2616b..8ecdbb2d237a30 100644
--- a/geyser-plugin-manager/src/lib.rs
+++ b/geyser-plugin-manager/src/lib.rs
@@ -1,3 +1,12 @@
+#![cfg_attr(
+    not(feature = "agave-unstable-api"),
+    deprecated(
+        since = "3.1.0",
+        note = "This crate has been marked for formal inclusion in the Agave Unstable API. From \
+                v4.0.0 onward, the `agave-unstable-api` crate feature must be specified to \
+                acknowledge use of an interface that may break without warning."
+    )
+)]
 pub mod accounts_update_notifier;
 pub mod block_metadata_notifier;
 pub mod block_metadata_notifier_interface;
diff --git a/gossip/src/lib.rs b/gossip/src/lib.rs
index 219aeffc16d704..00831e6b46426b 100644
--- a/gossip/src/lib.rs
+++ b/gossip/src/lib.rs
@@ -1,3 +1,12 @@
+#![cfg_attr(
+    not(feature = "agave-unstable-api"),
+    deprecated(
+        since = "3.1.0",
+        note = "This crate has been marked for formal inclusion in the Agave Unstable API. From \
+                v4.0.0 onward, the `agave-unstable-api` crate feature must be specified to \
+                acknowledge use of an interface that may break without warning."
+    )
+)]
 #![cfg_attr(feature = "frozen-abi", feature(min_specialization))]
 #![allow(clippy::arithmetic_side_effects)]
 // Activate some of the Rust 2024 lints to make the future migration easier.
diff --git a/gossip/src/node.rs b/gossip/src/node.rs
index 11367e79aa167b..f29f35513d2bd8 100644
--- a/gossip/src/node.rs
+++ b/gossip/src/node.rs
@@ -405,7 +405,6 @@ impl Node {
     }
 }
 
-#[cfg(feature = "agave-unstable-api")]
 mod multihoming {
     use {
         crate::{
@@ -519,5 +518,4 @@ mod multihoming {
     }
 }
 
-#[cfg(feature = "agave-unstable-api")]
 pub use multihoming::*;
diff --git a/io-uring/Cargo.toml b/io-uring/Cargo.toml
index d25485e11017eb..9891cb807a2dce 100644
--- a/io-uring/Cargo.toml
+++ b/io-uring/Cargo.toml
@@ -9,6 +9,9 @@ homepage = { workspace = true }
 license = { workspace = true }
 edition = { workspace = true }
 
+[features]
+agave-unstable-api = []
+
 [dependencies]
 libc = { workspace = true }
 log = { workspace = true }
diff --git a/io-uring/src/lib.rs b/io-uring/src/lib.rs
index d6edd6dd57c410..07775373791e21 100644
--- a/io-uring/src/lib.rs
+++ b/io-uring/src/lib.rs
@@ -1,3 +1,12 @@
+#![cfg_attr(
+    not(feature = "agave-unstable-api"),
+    deprecated(
+        since = "3.1.0",
+        note = "This crate has been marked for formal inclusion in the Agave Unstable API. From \
+                v4.0.0 onward, the `agave-unstable-api` crate feature must be specified to \
+                acknowledge use of an interface that may break without warning."
+    )
+)]
 #![cfg(target_os = "linux")]
 mod ring;
 mod slab;
diff --git a/lattice-hash/Cargo.toml b/lattice-hash/Cargo.toml
index 2ec387e8ad8b96..8f81ca5d33e668 100644
--- a/lattice-hash/Cargo.toml
+++ b/lattice-hash/Cargo.toml
@@ -8,6 +8,9 @@ homepage = { workspace = true }
 license = { workspace = true }
 edition = { workspace = true }
 
+[features]
+agave-unstable-api = []
+
 [dependencies]
 base64 = { workspace = true }
 blake3 = { workspace = true }
diff --git a/lattice-hash/src/lib.rs b/lattice-hash/src/lib.rs
index f40989f67d604b..d8715671ad347e 100644
--- a/lattice-hash/src/lib.rs
+++ b/lattice-hash/src/lib.rs
@@ -1 +1,10 @@
+#![cfg_attr(
+    not(feature = "agave-unstable-api"),
+    deprecated(
+        since = "3.1.0",
+        note = "This crate has been marked for formal inclusion in the Agave Unstable API. From \
+                v4.0.0 onward, the `agave-unstable-api` crate feature must be specified to \
+                acknowledge use of an interface that may break without warning."
+    )
+)]
 pub mod lt_hash;
diff --git a/ledger/src/lib.rs b/ledger/src/lib.rs
index 55afc6977ab835..b5a13e612f1a9b 100644
--- a/ledger/src/lib.rs
+++ b/ledger/src/lib.rs
@@ -1,3 +1,12 @@
+#![cfg_attr(
+    not(feature = "agave-unstable-api"),
+    deprecated(
+        since = "3.1.0",
+        note = "This crate has been marked for formal inclusion in the Agave Unstable API. From \
+                v4.0.0 onward, the `agave-unstable-api` crate feature must be specified to \
+                acknowledge use of an interface that may break without warning."
+    )
+)]
 #![cfg_attr(feature = "frozen-abi", feature(min_specialization))]
 #![allow(clippy::arithmetic_side_effects)]
 #![recursion_limit = "2048"]
diff --git a/local-cluster/Cargo.toml b/local-cluster/Cargo.toml
index 7c9d429213cd00..40a95a4b499b2b 100644
--- a/local-cluster/Cargo.toml
+++ b/local-cluster/Cargo.toml
@@ -13,6 +13,7 @@ edition = { workspace = true }
 targets = ["x86_64-unknown-linux-gnu"]
 
 [features]
+agave-unstable-api = []
 dev-context-only-utils = ["solana-core/dev-context-only-utils"]
 
 [dependencies]
diff --git a/local-cluster/src/lib.rs b/local-cluster/src/lib.rs
index 6a5b0c7032750e..a23c844043332a 100644
--- a/local-cluster/src/lib.rs
+++ b/local-cluster/src/lib.rs
@@ -1,3 +1,12 @@
+#![cfg_attr(
+    not(feature = "agave-unstable-api"),
+    deprecated(
+        since = "3.1.0",
+        note = "This crate has been marked for formal inclusion in the Agave Unstable API. From \
+                v4.0.0 onward, the `agave-unstable-api` crate feature must be specified to \
+                acknowledge use of an interface that may break without warning."
+    )
+)]
 #![allow(clippy::arithmetic_side_effects)]
 pub mod cluster;
 pub mod cluster_tests;
diff --git a/measure/Cargo.toml b/measure/Cargo.toml
index 090450251c752a..e933420e0dbe50 100644
--- a/measure/Cargo.toml
+++ b/measure/Cargo.toml
@@ -11,3 +11,6 @@ edition = { workspace = true }
 
 [package.metadata.docs.rs]
 targets = ["x86_64-unknown-linux-gnu"]
+
+[features]
+agave-unstable-api = []
diff --git a/measure/src/lib.rs b/measure/src/lib.rs
index a1c86feb89a43f..bb34e59763af42 100644
--- a/measure/src/lib.rs
+++ b/measure/src/lib.rs
@@ -1,3 +1,12 @@
+#![cfg_attr(
+    not(feature = "agave-unstable-api"),
+    deprecated(
+        since = "3.1.0",
+        note = "This crate has been marked for formal inclusion in the Agave Unstable API. From \
+                v4.0.0 onward, the `agave-unstable-api` crate feature must be specified to \
+                acknowledge use of an interface that may break without warning."
+    )
+)]
 #![allow(clippy::arithmetic_side_effects)]
 pub mod macros;
 pub mod measure;
diff --git a/memory-management/Cargo.toml b/memory-management/Cargo.toml
index bac18aaea0e791..de98779da49e3e 100644
--- a/memory-management/Cargo.toml
+++ b/memory-management/Cargo.toml
@@ -7,3 +7,6 @@ repository = { workspace = true }
 homepage = { workspace = true }
 license = { workspace = true }
 edition = { workspace = true }
+
+[features]
+agave-unstable-api = []
diff --git a/memory-management/src/lib.rs b/memory-management/src/lib.rs
index 95caf247cd5bb0..093e1219dda1fa 100644
--- a/memory-management/src/lib.rs
+++ b/memory-management/src/lib.rs
@@ -1,3 +1,12 @@
+#![cfg_attr(
+    not(feature = "agave-unstable-api"),
+    deprecated(
+        since = "3.1.0",
+        note = "This crate has been marked for formal inclusion in the Agave Unstable API. From \
+                v4.0.0 onward, the `agave-unstable-api` crate feature must be specified to \
+                acknowledge use of an interface that may break without warning."
+    )
+)]
 #![deny(clippy::arithmetic_side_effects)]
 pub mod aligned_memory;
 
diff --git a/merkle-tree/Cargo.toml b/merkle-tree/Cargo.toml
index 7993e255807e12..1b31febea981d8 100644
--- a/merkle-tree/Cargo.toml
+++ b/merkle-tree/Cargo.toml
@@ -16,6 +16,9 @@ targets = ["x86_64-unknown-linux-gnu"]
 crate-type = ["lib"]
 name = "solana_merkle_tree"
 
+[features]
+agave-unstable-api = []
+
 [dependencies]
 fast-math = { workspace = true }
 solana-hash = { workspace = true }
diff --git a/merkle-tree/src/lib.rs b/merkle-tree/src/lib.rs
index 606c487dcf84cb..fc452b9d64a105 100644
--- a/merkle-tree/src/lib.rs
+++ b/merkle-tree/src/lib.rs
@@ -1,3 +1,12 @@
+#![cfg_attr(
+    not(feature = "agave-unstable-api"),
+    deprecated(
+        since = "3.1.0",
+        note = "This crate has been marked for formal inclusion in the Agave Unstable API. From \
+                v4.0.0 onward, the `agave-unstable-api` crate feature must be specified to \
+                acknowledge use of an interface that may break without warning."
+    )
+)]
 #![allow(clippy::arithmetic_side_effects)]
 
 pub mod merkle_tree;
diff --git a/metrics/Cargo.toml b/metrics/Cargo.toml
index 7a073dfee2161a..fb142da7396565 100644
--- a/metrics/Cargo.toml
+++ b/metrics/Cargo.toml
@@ -15,6 +15,9 @@ targets = ["x86_64-unknown-linux-gnu"]
 [lib]
 name = "solana_metrics"
 
+[features]
+agave-unstable-api = []
+
 [dependencies]
 crossbeam-channel = { workspace = true }
 gethostname = { workspace = true }
diff --git a/metrics/src/lib.rs b/metrics/src/lib.rs
index e71c532d42b545..855a871725e27e 100644
--- a/metrics/src/lib.rs
+++ b/metrics/src/lib.rs
@@ -1,3 +1,12 @@
+#![cfg_attr(
+    not(feature = "agave-unstable-api"),
+    deprecated(
+        since = "3.1.0",
+        note = "This crate has been marked for formal inclusion in the Agave Unstable API. From \
+                v4.0.0 onward, the `agave-unstable-api` crate feature must be specified to \
+                acknowledge use of an interface that may break without warning."
+    )
+)]
 #![allow(clippy::arithmetic_side_effects)]
 pub mod counter;
 pub mod datapoint;
diff --git a/net-utils/Cargo.toml b/net-utils/Cargo.toml
index 8c7bc64bebc0cc..5c154da0420aaa 100644
--- a/net-utils/Cargo.toml
+++ b/net-utils/Cargo.toml
@@ -17,7 +17,6 @@ name = "solana_net_utils"
 
 [features]
 agave-unstable-api = []
-default = []
 dev-context-only-utils = ["dep:pcap-file", "dep:hxdmp"]
 shuttle-test = ["dep:shuttle", "solana-svm-type-overrides/shuttle-test"]
 
diff --git a/net-utils/src/lib.rs b/net-utils/src/lib.rs
index b3c9205909ade8..d17dc9a8d873ee 100644
--- a/net-utils/src/lib.rs
+++ b/net-utils/src/lib.rs
@@ -1,3 +1,12 @@
+#![cfg_attr(
+    not(feature = "agave-unstable-api"),
+    deprecated(
+        since = "3.1.0",
+        note = "This crate has been marked for formal inclusion in the Agave Unstable API. From \
+                v4.0.0 onward, the `agave-unstable-api` crate feature must be specified to \
+                acknowledge use of an interface that may break without warning."
+    )
+)]
 //! The `net_utils` module assists with networking
 
 // Activate some of the Rust 2024 lints to make the future migration easier.
diff --git a/notifier/Cargo.toml b/notifier/Cargo.toml
index ba5dcb2a74e3a4..4299bdf42ee61a 100644
--- a/notifier/Cargo.toml
+++ b/notifier/Cargo.toml
@@ -15,6 +15,9 @@ targets = ["x86_64-unknown-linux-gnu"]
 [lib]
 name = "solana_notifier"
 
+[features]
+agave-unstable-api = []
+
 [dependencies]
 log = { workspace = true }
 reqwest = { workspace = true, features = ["blocking", "brotli", "deflate", "gzip", "rustls-tls", "json"] }
diff --git a/notifier/src/lib.rs b/notifier/src/lib.rs
index 41beede3bd2052..267a528a1615fa 100644
--- a/notifier/src/lib.rs
+++ b/notifier/src/lib.rs
@@ -1,3 +1,12 @@
+#![cfg_attr(
+    not(feature = "agave-unstable-api"),
+    deprecated(
+        since = "3.1.0",
+        note = "This crate has been marked for formal inclusion in the Agave Unstable API. From \
+                v4.0.0 onward, the `agave-unstable-api` crate feature must be specified to \
+                acknowledge use of an interface that may break without warning."
+    )
+)]
 /// To activate Slack, Discord, PagerDuty and/or Telegram notifications, define these environment variables
 /// before using the `Notifier`
 /// ```bash
diff --git a/perf/Cargo.toml b/perf/Cargo.toml
index b0a6c8c64bb1b0..5388ea915cc1b1 100644
--- a/perf/Cargo.toml
+++ b/perf/Cargo.toml
@@ -16,6 +16,7 @@ targets = ["x86_64-unknown-linux-gnu"]
 name = "solana_perf"
 
 [features]
+agave-unstable-api = []
 dev-context-only-utils = [
     "dep:solana-clock",
     "dep:solana-keypair",
diff --git a/perf/src/lib.rs b/perf/src/lib.rs
index 864d541c8746f1..64bc843184a482 100644
--- a/perf/src/lib.rs
+++ b/perf/src/lib.rs
@@ -1,3 +1,12 @@
+#![cfg_attr(
+    not(feature = "agave-unstable-api"),
+    deprecated(
+        since = "3.1.0",
+        note = "This crate has been marked for formal inclusion in the Agave Unstable API. From \
+                v4.0.0 onward, the `agave-unstable-api` crate feature must be specified to \
+                acknowledge use of an interface that may break without warning."
+    )
+)]
 #![cfg_attr(feature = "frozen-abi", feature(min_specialization))]
 pub mod cuda_runtime;
 pub mod data_budget;
diff --git a/poh/Cargo.toml b/poh/Cargo.toml
index 3a2d1ba846fa82..03eadc2acc6585 100644
--- a/poh/Cargo.toml
+++ b/poh/Cargo.toml
@@ -17,6 +17,7 @@ crate-type = ["lib"]
 name = "solana_poh"
 
 [features]
+agave-unstable-api = []
 dev-context-only-utils = []
 shuttle-test = ["dep:shuttle"]
 
diff --git a/poh/src/lib.rs b/poh/src/lib.rs
index c58abd71106412..c78cbd112ad4d5 100644
--- a/poh/src/lib.rs
+++ b/poh/src/lib.rs
@@ -1,3 +1,12 @@
+#![cfg_attr(
+    not(feature = "agave-unstable-api"),
+    deprecated(
+        since = "3.1.0",
+        note = "This crate has been marked for formal inclusion in the Agave Unstable API. From \
+                v4.0.0 onward, the `agave-unstable-api` crate feature must be specified to \
+                acknowledge use of an interface that may break without warning."
+    )
+)]
 #![allow(clippy::arithmetic_side_effects)]
 pub mod poh_controller;
 pub mod poh_recorder;
diff --git a/poseidon/Cargo.toml b/poseidon/Cargo.toml
index 7b41042855b9ec..1bd00ca10f9074 100644
--- a/poseidon/Cargo.toml
+++ b/poseidon/Cargo.toml
@@ -12,6 +12,9 @@ edition = { workspace = true }
 [package.metadata.docs.rs]
 targets = ["x86_64-unknown-linux-gnu"]
 
+[features]
+agave-unstable-api = []
+
 [dependencies]
 thiserror = { workspace = true }
 
diff --git a/poseidon/src/lib.rs b/poseidon/src/lib.rs
index 698352cf04c686..698f77783fe97e 100644
--- a/poseidon/src/lib.rs
+++ b/poseidon/src/lib.rs
@@ -1,3 +1,12 @@
+#![cfg_attr(
+    not(feature = "agave-unstable-api"),
+    deprecated(
+        since = "3.1.0",
+        note = "This crate has been marked for formal inclusion in the Agave Unstable API. From \
+                v4.0.0 onward, the `agave-unstable-api` crate feature must be specified to \
+                acknowledge use of an interface that may break without warning."
+    )
+)]
 //! Hashing with the [Poseidon] hash function.
 //!
 //! [Poseidon]: https://www.poseidon-hash.info/
diff --git a/precompiles/Cargo.toml b/precompiles/Cargo.toml
index d67c1f2d7c4a98..2eae7c55e6aba2 100644
--- a/precompiles/Cargo.toml
+++ b/precompiles/Cargo.toml
@@ -14,6 +14,9 @@ targets = ["x86_64-unknown-linux-gnu"]
 all-features = true
 rustdoc-args = ["--cfg=docsrs"]
 
+[features]
+agave-unstable-api = []
+
 [dependencies]
 agave-feature-set = { workspace = true }
 bincode = { workspace = true }
diff --git a/precompiles/src/lib.rs b/precompiles/src/lib.rs
index ee09da940c065d..bbb4382cf35243 100644
--- a/precompiles/src/lib.rs
+++ b/precompiles/src/lib.rs
@@ -1,3 +1,12 @@
+#![cfg_attr(
+    not(feature = "agave-unstable-api"),
+    deprecated(
+        since = "3.1.0",
+        note = "This crate has been marked for formal inclusion in the Agave Unstable API. From \
+                v4.0.0 onward, the `agave-unstable-api` crate feature must be specified to \
+                acknowledge use of an interface that may break without warning."
+    )
+)]
 #![cfg_attr(docsrs, feature(doc_auto_cfg))]
 use {
     agave_feature_set::{enable_secp256r1_precompile, FeatureSet},
diff --git a/program-binaries/Cargo.toml b/program-binaries/Cargo.toml
index 2c06b3ac629b88..c2d9d6174c8a12 100644
--- a/program-binaries/Cargo.toml
+++ b/program-binaries/Cargo.toml
@@ -8,6 +8,9 @@ homepage = { workspace = true }
 license = { workspace = true }
 edition = { workspace = true }
 
+[features]
+agave-unstable-api = []
+
 [dependencies]
 bincode = { workspace = true }
 serde = { workspace = true }
diff --git a/program-binaries/src/lib.rs b/program-binaries/src/lib.rs
index 4776a98d33d3ac..baf934fc5755eb 100644
--- a/program-binaries/src/lib.rs
+++ b/program-binaries/src/lib.rs
@@ -1,3 +1,12 @@
+#![cfg_attr(
+    not(feature = "agave-unstable-api"),
+    deprecated(
+        since = "3.1.0",
+        note = "This crate has been marked for formal inclusion in the Agave Unstable API. From \
+                v4.0.0 onward, the `agave-unstable-api` crate feature must be specified to \
+                acknowledge use of an interface that may break without warning."
+    )
+)]
 #![allow(clippy::arithmetic_side_effects)]
 
 use {
diff --git a/program-runtime/Cargo.toml b/program-runtime/Cargo.toml
index b10814821e6e14..478e8a3ea6ade1 100644
--- a/program-runtime/Cargo.toml
+++ b/program-runtime/Cargo.toml
@@ -17,6 +17,7 @@ crate-type = ["lib"]
 name = "solana_program_runtime"
 
 [features]
+agave-unstable-api = []
 dev-context-only-utils = []
 dummy-for-ci-check = ["metrics"]
 frozen-abi = ["dep:solana-frozen-abi", "dep:solana-frozen-abi-macro"]
diff --git a/program-runtime/src/lib.rs b/program-runtime/src/lib.rs
index e302e59bada7d1..31d6d9338c726c 100644
--- a/program-runtime/src/lib.rs
+++ b/program-runtime/src/lib.rs
@@ -1,3 +1,12 @@
+#![cfg_attr(
+    not(feature = "agave-unstable-api"),
+    deprecated(
+        since = "3.1.0",
+        note = "This crate has been marked for formal inclusion in the Agave Unstable API. From \
+                v4.0.0 onward, the `agave-unstable-api` crate feature must be specified to \
+                acknowledge use of an interface that may break without warning."
+    )
+)]
 #![cfg_attr(feature = "frozen-abi", feature(min_specialization))]
 #![deny(clippy::arithmetic_side_effects)]
 #![deny(clippy::indexing_slicing)]
diff --git a/program-test/Cargo.toml b/program-test/Cargo.toml
index e2dc3bdac743b5..5fc810858bdd4d 100644
--- a/program-test/Cargo.toml
+++ b/program-test/Cargo.toml
@@ -8,6 +8,9 @@ homepage = { workspace = true }
 license = { workspace = true }
 edition = { workspace = true }
 
+[features]
+agave-unstable-api = []
+
 [dependencies]
 agave-feature-set = { workspace = true }
 assert_matches = { workspace = true }
diff --git a/program-test/src/lib.rs b/program-test/src/lib.rs
index 87a83405f17b8f..33e4db2f5a3fc3 100644
--- a/program-test/src/lib.rs
+++ b/program-test/src/lib.rs
@@ -1,3 +1,12 @@
+#![cfg_attr(
+    not(feature = "agave-unstable-api"),
+    deprecated(
+        since = "3.1.0",
+        note = "This crate has been marked for formal inclusion in the Agave Unstable API. From \
+                v4.0.0 onward, the `agave-unstable-api` crate feature must be specified to \
+                acknowledge use of an interface that may break without warning."
+    )
+)]
 //! The solana-program-test provides a BanksClient-based test framework SBF programs
 #![allow(clippy::arithmetic_side_effects)]
 
diff --git a/programs/bpf_loader/Cargo.toml b/programs/bpf_loader/Cargo.toml
index 5b46ce2955eeea..cba3931999287c 100644
--- a/programs/bpf_loader/Cargo.toml
+++ b/programs/bpf_loader/Cargo.toml
@@ -18,6 +18,7 @@ name = "solana_bpf_loader_program"
 
 [features]
 default = ["metrics"]
+agave-unstable-api = []
 metrics = ["solana-program-runtime/metrics"]
 shuttle-test = [
     "solana-program-runtime/shuttle-test",
diff --git a/programs/bpf_loader/src/lib.rs b/programs/bpf_loader/src/lib.rs
index d4478b4b3574f1..22d7bdfd5c3222 100644
--- a/programs/bpf_loader/src/lib.rs
+++ b/programs/bpf_loader/src/lib.rs
@@ -1,3 +1,12 @@
+#![cfg_attr(
+    not(feature = "agave-unstable-api"),
+    deprecated(
+        since = "3.1.0",
+        note = "This crate has been marked for formal inclusion in the Agave Unstable API. From \
+                v4.0.0 onward, the `agave-unstable-api` crate feature must be specified to \
+                acknowledge use of an interface that may break without warning."
+    )
+)]
 #![deny(clippy::arithmetic_side_effects)]
 #![deny(clippy::indexing_slicing)]
 
diff --git a/programs/compute-budget/Cargo.toml b/programs/compute-budget/Cargo.toml
index b8262283f40afd..722526b6b09d88 100644
--- a/programs/compute-budget/Cargo.toml
+++ b/programs/compute-budget/Cargo.toml
@@ -16,5 +16,8 @@ targets = ["x86_64-unknown-linux-gnu"]
 crate-type = ["lib"]
 name = "solana_compute_budget_program"
 
+[features]
+agave-unstable-api = []
+
 [dependencies]
 solana-program-runtime = { workspace = true }
diff --git a/programs/compute-budget/src/lib.rs b/programs/compute-budget/src/lib.rs
index 01bbd7a8b4f21c..45fd7d3ada0176 100644
--- a/programs/compute-budget/src/lib.rs
+++ b/programs/compute-budget/src/lib.rs
@@ -1,3 +1,12 @@
+#![cfg_attr(
+    not(feature = "agave-unstable-api"),
+    deprecated(
+        since = "3.1.0",
+        note = "This crate has been marked for formal inclusion in the Agave Unstable API. From \
+                v4.0.0 onward, the `agave-unstable-api` crate feature must be specified to \
+                acknowledge use of an interface that may break without warning."
+    )
+)]
 use solana_program_runtime::declare_process_instruction;
 
 pub const DEFAULT_COMPUTE_UNITS: u64 = 150;
diff --git a/programs/loader-v4/Cargo.toml b/programs/loader-v4/Cargo.toml
index e525742d626cdc..4c5a29af666145 100644
--- a/programs/loader-v4/Cargo.toml
+++ b/programs/loader-v4/Cargo.toml
@@ -26,7 +26,6 @@ svm-internal = []
 
 [dependencies]
 log = { workspace = true }
-qualifier_attr = { workspace = true }
 solana-account = { workspace = true }
 solana-bincode = { workspace = true }
 solana-bpf-loader-program = { workspace = true, features = ["svm-internal"] }
diff --git a/programs/loader-v4/src/lib.rs b/programs/loader-v4/src/lib.rs
index c2591e8b1cf6b7..45da0d9b143100 100644
--- a/programs/loader-v4/src/lib.rs
+++ b/programs/loader-v4/src/lib.rs
@@ -1,5 +1,12 @@
-#[cfg(feature = "agave-unstable-api")]
-use qualifier_attr::qualifiers;
+#![cfg_attr(
+    not(feature = "agave-unstable-api"),
+    deprecated(
+        since = "3.1.0",
+        note = "This crate has been marked for formal inclusion in the Agave Unstable API. From \
+                v4.0.0 onward, the `agave-unstable-api` crate feature must be specified to \
+                acknowledge use of an interface that may break without warning."
+    )
+)]
 use {
     solana_bincode::limited_deserialize,
     solana_bpf_loader_program::{deploy_program, execute},
@@ -24,7 +31,6 @@ use {
     std::{cell::RefCell, rc::Rc},
 };
 
-#[cfg_attr(feature = "agave-unstable-api", qualifiers(pub))]
 const DEFAULT_COMPUTE_UNITS: u64 = 2_000;
 
 pub fn get_state(data: &[u8]) -> Result<&LoaderV4State, InstructionError> {
diff --git a/programs/sbf/Cargo.lock b/programs/sbf/Cargo.lock
index 52c925f953aecf..7c941626e48d5c 100644
--- a/programs/sbf/Cargo.lock
+++ b/programs/sbf/Cargo.lock
@@ -7311,7 +7311,6 @@ name = "solana-loader-v4-program"
 version = "3.1.0"
 dependencies = [
  "log",
- "qualifier_attr",
  "solana-account",
  "solana-bincode",
  "solana-bpf-loader-program",
diff --git a/programs/stake/Cargo.toml b/programs/stake/Cargo.toml
index 7f2573e16c1042..3e7104a75a0c5c 100644
--- a/programs/stake/Cargo.toml
+++ b/programs/stake/Cargo.toml
@@ -16,6 +16,9 @@ targets = ["x86_64-unknown-linux-gnu"]
 crate-type = ["lib"]
 name = "solana_stake_program"
 
+[features]
+agave-unstable-api = []
+
 [dependencies]
 agave-feature-set = { workspace = true }
 bincode = { workspace = true }
diff --git a/programs/stake/src/lib.rs b/programs/stake/src/lib.rs
index d5b792f70f970e..0abea51ec9ec7f 100644
--- a/programs/stake/src/lib.rs
+++ b/programs/stake/src/lib.rs
@@ -1,3 +1,12 @@
+#![cfg_attr(
+    not(feature = "agave-unstable-api"),
+    deprecated(
+        since = "3.1.0",
+        note = "This crate has been marked for formal inclusion in the Agave Unstable API. From \
+                v4.0.0 onward, the `agave-unstable-api` crate feature must be specified to \
+                acknowledge use of an interface that may break without warning."
+    )
+)]
 #![cfg_attr(feature = "frozen-abi", feature(min_specialization))]
 #![allow(clippy::arithmetic_side_effects)]
 #[deprecated(
diff --git a/programs/system/Cargo.toml b/programs/system/Cargo.toml
index f685a410c3691d..6df465cf18bf19 100644
--- a/programs/system/Cargo.toml
+++ b/programs/system/Cargo.toml
@@ -16,6 +16,9 @@ targets = ["x86_64-unknown-linux-gnu"]
 crate-type = ["lib"]
 name = "solana_system_program"
 
+[features]
+agave-unstable-api = []
+
 [dependencies]
 bincode = { workspace = true }
 log = { workspace = true }
diff --git a/programs/system/src/lib.rs b/programs/system/src/lib.rs
index 1911e279f364d3..b8b1338476b351 100644
--- a/programs/system/src/lib.rs
+++ b/programs/system/src/lib.rs
@@ -1,3 +1,12 @@
+#![cfg_attr(
+    not(feature = "agave-unstable-api"),
+    deprecated(
+        since = "3.1.0",
+        note = "This crate has been marked for formal inclusion in the Agave Unstable API. From \
+                v4.0.0 onward, the `agave-unstable-api` crate feature must be specified to \
+                acknowledge use of an interface that may break without warning."
+    )
+)]
 #![allow(clippy::arithmetic_side_effects)]
 pub mod system_instruction;
 pub mod system_processor;
diff --git a/programs/vote/Cargo.toml b/programs/vote/Cargo.toml
index 01d2088963dd17..9208a9efb7de8c 100644
--- a/programs/vote/Cargo.toml
+++ b/programs/vote/Cargo.toml
@@ -18,6 +18,7 @@ name = "solana_vote_program"
 
 [features]
 default = ["metrics"]
+agave-unstable-api = []
 frozen-abi = [
     "dep:solana-frozen-abi",
     "dep:solana-frozen-abi-macro",
diff --git a/programs/vote/src/lib.rs b/programs/vote/src/lib.rs
index 280949b282d4fe..d9877c8868b3b6 100644
--- a/programs/vote/src/lib.rs
+++ b/programs/vote/src/lib.rs
@@ -1,3 +1,12 @@
+#![cfg_attr(
+    not(feature = "agave-unstable-api"),
+    deprecated(
+        since = "3.1.0",
+        note = "This crate has been marked for formal inclusion in the Agave Unstable API. From \
+                v4.0.0 onward, the `agave-unstable-api` crate feature must be specified to \
+                acknowledge use of an interface that may break without warning."
+    )
+)]
 #![cfg_attr(feature = "frozen-abi", feature(min_specialization))]
 
 pub mod vote_processor;
diff --git a/programs/zk-elgamal-proof/Cargo.toml b/programs/zk-elgamal-proof/Cargo.toml
index 73004c715fa7d4..a1358061dd2ed4 100644
--- a/programs/zk-elgamal-proof/Cargo.toml
+++ b/programs/zk-elgamal-proof/Cargo.toml
@@ -8,6 +8,9 @@ homepage = { workspace = true }
 license = { workspace = true }
 edition = { workspace = true }
 
+[features]
+agave-unstable-api = []
+
 [dependencies]
 agave-feature-set = { workspace = true }
 bytemuck = { workspace = true }
diff --git a/programs/zk-elgamal-proof/src/lib.rs b/programs/zk-elgamal-proof/src/lib.rs
index 17bf5ab9cdd951..b9809b81022464 100644
--- a/programs/zk-elgamal-proof/src/lib.rs
+++ b/programs/zk-elgamal-proof/src/lib.rs
@@ -1,3 +1,12 @@
+#![cfg_attr(
+    not(feature = "agave-unstable-api"),
+    deprecated(
+        since = "3.1.0",
+        note = "This crate has been marked for formal inclusion in the Agave Unstable API. From \
+                v4.0.0 onward, the `agave-unstable-api` crate feature must be specified to \
+                acknowledge use of an interface that may break without warning."
+    )
+)]
 #![forbid(unsafe_code)]
 
 use {
diff --git a/programs/zk-token-proof/Cargo.toml b/programs/zk-token-proof/Cargo.toml
index e9f5f6fb8d928d..e58cb3b021289c 100644
--- a/programs/zk-token-proof/Cargo.toml
+++ b/programs/zk-token-proof/Cargo.toml
@@ -8,6 +8,9 @@ homepage = { workspace = true }
 license = { workspace = true }
 edition = { workspace = true }
 
+[features]
+agave-unstable-api = []
+
 [dependencies]
 agave-feature-set = { workspace = true }
 bytemuck = { workspace = true }
diff --git a/programs/zk-token-proof/src/lib.rs b/programs/zk-token-proof/src/lib.rs
index 5f5e4c8ac2af0f..4961069ec58fec 100644
--- a/programs/zk-token-proof/src/lib.rs
+++ b/programs/zk-token-proof/src/lib.rs
@@ -1,3 +1,12 @@
+#![cfg_attr(
+    not(feature = "agave-unstable-api"),
+    deprecated(
+        since = "3.1.0",
+        note = "This crate has been marked for formal inclusion in the Agave Unstable API. From \
+                v4.0.0 onward, the `agave-unstable-api` crate feature must be specified to \
+                acknowledge use of an interface that may break without warning."
+    )
+)]
 #![forbid(unsafe_code)]
 // Allow deprecated warnings since this crate will be removed along with
 // `solana-zk-token-sdk` will be removed
diff --git a/pubsub-client/Cargo.toml b/pubsub-client/Cargo.toml
index 54bef1f14400d9..ef879e303877b7 100644
--- a/pubsub-client/Cargo.toml
+++ b/pubsub-client/Cargo.toml
@@ -12,6 +12,9 @@ edition = { workspace = true }
 [package.metadata.docs.rs]
 targets = ["x86_64-unknown-linux-gnu"]
 
+[features]
+agave-unstable-api = []
+
 [dependencies]
 crossbeam-channel = { workspace = true }
 futures-util = { workspace = true }
diff --git a/pubsub-client/src/lib.rs b/pubsub-client/src/lib.rs
index d572ee53397183..a0842f53203900 100644
--- a/pubsub-client/src/lib.rs
+++ b/pubsub-client/src/lib.rs
@@ -1,3 +1,12 @@
+#![cfg_attr(
+    not(feature = "agave-unstable-api"),
+    deprecated(
+        since = "3.1.0",
+        note = "This crate has been marked for formal inclusion in the Agave Unstable API. From \
+                v4.0.0 onward, the `agave-unstable-api` crate feature must be specified to \
+                acknowledge use of an interface that may break without warning."
+    )
+)]
 #![allow(clippy::arithmetic_side_effects)]
 
 pub mod nonblocking;
diff --git a/quic-client/Cargo.toml b/quic-client/Cargo.toml
index 1427c56a35d235..5f4b65d5072227 100644
--- a/quic-client/Cargo.toml
+++ b/quic-client/Cargo.toml
@@ -9,6 +9,9 @@ homepage = { workspace = true }
 license = { workspace = true }
 edition = { workspace = true }
 
+[features]
+agave-unstable-api = []
+
 [dependencies]
 async-lock = { workspace = true }
 async-trait = { workspace = true }
diff --git a/quic-client/src/lib.rs b/quic-client/src/lib.rs
index 930a0cc078fbc9..70c3fcedfafca4 100644
--- a/quic-client/src/lib.rs
+++ b/quic-client/src/lib.rs
@@ -1,3 +1,12 @@
+#![cfg_attr(
+    not(feature = "agave-unstable-api"),
+    deprecated(
+        since = "3.1.0",
+        note = "This crate has been marked for formal inclusion in the Agave Unstable API. From \
+                v4.0.0 onward, the `agave-unstable-api` crate feature must be specified to \
+                acknowledge use of an interface that may break without warning."
+    )
+)]
 #![allow(clippy::arithmetic_side_effects)]
 
 pub mod nonblocking;
diff --git a/rayon-threadlimit/Cargo.toml b/rayon-threadlimit/Cargo.toml
index b7431f2db4907c..f357a5d2f4bc23 100644
--- a/rayon-threadlimit/Cargo.toml
+++ b/rayon-threadlimit/Cargo.toml
@@ -12,6 +12,9 @@ edition = { workspace = true }
 [package.metadata.docs.rs]
 targets = ["x86_64-unknown-linux-gnu"]
 
+[features]
+agave-unstable-api = []
+
 [dependencies]
 log = { workspace = true }
 num_cpus = { workspace = true }
diff --git a/rayon-threadlimit/src/lib.rs b/rayon-threadlimit/src/lib.rs
index e12d3584b81d23..5f36fbd6547aec 100644
--- a/rayon-threadlimit/src/lib.rs
+++ b/rayon-threadlimit/src/lib.rs
@@ -1,3 +1,12 @@
+#![cfg_attr(
+    not(feature = "agave-unstable-api"),
+    deprecated(
+        since = "3.1.0",
+        note = "This crate has been marked for formal inclusion in the Agave Unstable API. From \
+                v4.0.0 onward, the `agave-unstable-api` crate feature must be specified to \
+                acknowledge use of an interface that may break without warning."
+    )
+)]
 use {log::warn, std::env};
 //TODO remove this hack when rayon fixes itself
 
diff --git a/remote-wallet/Cargo.toml b/remote-wallet/Cargo.toml
index 3eebb582e32204..e7ea04635242aa 100644
--- a/remote-wallet/Cargo.toml
+++ b/remote-wallet/Cargo.toml
@@ -14,6 +14,7 @@ targets = ["x86_64-unknown-linux-gnu"]
 
 [features]
 default = ["linux-static-hidraw"]
+agave-unstable-api = []
 linux-shared-hidraw = ["hidapi/linux-shared-hidraw"]
 linux-shared-libusb = ["hidapi/linux-shared-libusb"]
 linux-static-hidraw = ["hidapi/linux-static-hidraw"]
diff --git a/remote-wallet/src/lib.rs b/remote-wallet/src/lib.rs
index 2400850734b1c1..5b23fed4f114f9 100644
--- a/remote-wallet/src/lib.rs
+++ b/remote-wallet/src/lib.rs
@@ -1,3 +1,12 @@
+#![cfg_attr(
+    not(feature = "agave-unstable-api"),
+    deprecated(
+        since = "3.1.0",
+        note = "This crate has been marked for formal inclusion in the Agave Unstable API. From \
+                v4.0.0 onward, the `agave-unstable-api` crate feature must be specified to \
+                acknowledge use of an interface that may break without warning."
+    )
+)]
 #![allow(clippy::arithmetic_side_effects)]
 #![allow(dead_code)]
 pub mod ledger;
diff --git a/reserved-account-keys/Cargo.toml b/reserved-account-keys/Cargo.toml
index ac1ad6f443d9d7..fa6c6259e43ea4 100644
--- a/reserved-account-keys/Cargo.toml
+++ b/reserved-account-keys/Cargo.toml
@@ -15,6 +15,7 @@ all-features = true
 rustdoc-args = ["--cfg=docsrs"]
 
 [features]
+agave-unstable-api = []
 frozen-abi = ["dep:solana-frozen-abi", "dep:solana-frozen-abi-macro"]
 
 [dependencies]
diff --git a/reserved-account-keys/src/lib.rs b/reserved-account-keys/src/lib.rs
index f4a22835112d74..9a5a4f80b7e335 100644
--- a/reserved-account-keys/src/lib.rs
+++ b/reserved-account-keys/src/lib.rs
@@ -1,3 +1,12 @@
+#![cfg_attr(
+    not(feature = "agave-unstable-api"),
+    deprecated(
+        since = "3.1.0",
+        note = "This crate has been marked for formal inclusion in the Agave Unstable API. From \
+                v4.0.0 onward, the `agave-unstable-api` crate feature must be specified to \
+                acknowledge use of an interface that may break without warning."
+    )
+)]
 //! Collection of reserved account keys that cannot be write-locked by transactions.
 //! New reserved account keys may be added as long as they specify a feature
 //! gate that transitions the key into read-only at an epoch boundary.
diff --git a/rpc-client-api/Cargo.toml b/rpc-client-api/Cargo.toml
index 7a8a53c610bbe5..1a18f44901e2be 100644
--- a/rpc-client-api/Cargo.toml
+++ b/rpc-client-api/Cargo.toml
@@ -12,6 +12,9 @@ edition = { workspace = true }
 [package.metadata.docs.rs]
 targets = ["x86_64-unknown-linux-gnu"]
 
+[features]
+agave-unstable-api = []
+
 [dependencies]
 anyhow = { workspace = true }
 jsonrpc-core = { workspace = true }
diff --git a/rpc-client-api/src/lib.rs b/rpc-client-api/src/lib.rs
index 1974e58ff319a4..250e420e3077d3 100644
--- a/rpc-client-api/src/lib.rs
+++ b/rpc-client-api/src/lib.rs
@@ -1,3 +1,12 @@
+#![cfg_attr(
+    not(feature = "agave-unstable-api"),
+    deprecated(
+        since = "3.1.0",
+        note = "This crate has been marked for formal inclusion in the Agave Unstable API. From \
+                v4.0.0 onward, the `agave-unstable-api` crate feature must be specified to \
+                acknowledge use of an interface that may break without warning."
+    )
+)]
 #![allow(clippy::arithmetic_side_effects)]
 
 pub mod client_error;
diff --git a/rpc-client-nonce-utils/Cargo.toml b/rpc-client-nonce-utils/Cargo.toml
index 85c732716af6a4..55eab78f8a4eda 100644
--- a/rpc-client-nonce-utils/Cargo.toml
+++ b/rpc-client-nonce-utils/Cargo.toml
@@ -14,6 +14,7 @@ targets = ["x86_64-unknown-linux-gnu"]
 
 [features]
 default = []
+agave-unstable-api = []
 clap = ["dep:clap", "dep:solana-clap-utils"]
 
 [dependencies]
diff --git a/rpc-client-nonce-utils/src/lib.rs b/rpc-client-nonce-utils/src/lib.rs
index aca27e6c993e61..d5eb9cb6d781c9 100644
--- a/rpc-client-nonce-utils/src/lib.rs
+++ b/rpc-client-nonce-utils/src/lib.rs
@@ -1,3 +1,12 @@
+#![cfg_attr(
+    not(feature = "agave-unstable-api"),
+    deprecated(
+        since = "3.1.0",
+        note = "This crate has been marked for formal inclusion in the Agave Unstable API. From \
+                v4.0.0 onward, the `agave-unstable-api` crate feature must be specified to \
+                acknowledge use of an interface that may break without warning."
+    )
+)]
 //! Durable transaction nonce helpers.
 
 pub mod blockhash_query;
diff --git a/rpc-client-types/Cargo.toml b/rpc-client-types/Cargo.toml
index 38fde49f235322..7ab3f1c139f71c 100644
--- a/rpc-client-types/Cargo.toml
+++ b/rpc-client-types/Cargo.toml
@@ -12,6 +12,9 @@ edition = { workspace = true }
 [package.metadata.docs.rs]
 targets = ["x86_64-unknown-linux-gnu"]
 
+[features]
+agave-unstable-api = []
+
 [dependencies]
 base64 = { workspace = true }
 bs58 = { workspace = true, features = ["std"] }
diff --git a/rpc-client-types/src/lib.rs b/rpc-client-types/src/lib.rs
index 86e81c1126a958..7e83fd08875096 100644
--- a/rpc-client-types/src/lib.rs
+++ b/rpc-client-types/src/lib.rs
@@ -1,3 +1,12 @@
+#![cfg_attr(
+    not(feature = "agave-unstable-api"),
+    deprecated(
+        since = "3.1.0",
+        note = "This crate has been marked for formal inclusion in the Agave Unstable API. From \
+                v4.0.0 onward, the `agave-unstable-api` crate feature must be specified to \
+                acknowledge use of an interface that may break without warning."
+    )
+)]
 #![allow(clippy::arithmetic_side_effects)]
 
 pub mod config;
diff --git a/rpc-client/Cargo.toml b/rpc-client/Cargo.toml
index 007b70ac8d29a0..f8064739f1c45b 100644
--- a/rpc-client/Cargo.toml
+++ b/rpc-client/Cargo.toml
@@ -14,6 +14,7 @@ targets = ["x86_64-unknown-linux-gnu"]
 
 [features]
 default = ["spinner"]
+agave-unstable-api = []
 # Support rpc-client methods that feature a spinner progress bar for
 # command-line interfaces
 spinner = ["dep:indicatif"]
diff --git a/rpc-client/src/lib.rs b/rpc-client/src/lib.rs
index c178ee55ea7d1d..1010e7933fdc44 100644
--- a/rpc-client/src/lib.rs
+++ b/rpc-client/src/lib.rs
@@ -1,3 +1,12 @@
+#![cfg_attr(
+    not(feature = "agave-unstable-api"),
+    deprecated(
+        since = "3.1.0",
+        note = "This crate has been marked for formal inclusion in the Agave Unstable API. From \
+                v4.0.0 onward, the `agave-unstable-api` crate feature must be specified to \
+                acknowledge use of an interface that may break without warning."
+    )
+)]
 #![allow(clippy::arithmetic_side_effects)]
 
 pub mod http_sender;
diff --git a/rpc/Cargo.toml b/rpc/Cargo.toml
index 83ac31c0c2df3f..09ba2fbfe1b177 100644
--- a/rpc/Cargo.toml
+++ b/rpc/Cargo.toml
@@ -17,6 +17,7 @@ crate-type = ["lib"]
 name = "solana_rpc"
 
 [features]
+agave-unstable-api = []
 dev-context-only-utils = [
     "solana-ledger/dev-context-only-utils",
     "solana-rpc/dev-context-only-utils",
diff --git a/rpc/src/lib.rs b/rpc/src/lib.rs
index abbc8d87a62499..72ca6de33a9ba7 100644
--- a/rpc/src/lib.rs
+++ b/rpc/src/lib.rs
@@ -1,3 +1,12 @@
+#![cfg_attr(
+    not(feature = "agave-unstable-api"),
+    deprecated(
+        since = "3.1.0",
+        note = "This crate has been marked for formal inclusion in the Agave Unstable API. From \
+                v4.0.0 onward, the `agave-unstable-api` crate feature must be specified to \
+                acknowledge use of an interface that may break without warning."
+    )
+)]
 #![allow(clippy::arithmetic_side_effects)]
 mod cluster_tpu_info;
 pub mod filter;
diff --git a/runtime-transaction/Cargo.toml b/runtime-transaction/Cargo.toml
index f9974cb37080b5..5eca8414779b97 100644
--- a/runtime-transaction/Cargo.toml
+++ b/runtime-transaction/Cargo.toml
@@ -17,6 +17,7 @@ crate-type = ["lib"]
 name = "solana_runtime_transaction"
 
 [features]
+agave-unstable-api = []
 dev-context-only-utils = ["solana-compute-budget-instruction/dev-context-only-utils"]
 
 [dependencies]
diff --git a/runtime-transaction/src/lib.rs b/runtime-transaction/src/lib.rs
index bc66573ce1d2bc..d01abdc7d96313 100644
--- a/runtime-transaction/src/lib.rs
+++ b/runtime-transaction/src/lib.rs
@@ -1,3 +1,12 @@
+#![cfg_attr(
+    not(feature = "agave-unstable-api"),
+    deprecated(
+        since = "3.1.0",
+        note = "This crate has been marked for formal inclusion in the Agave Unstable API. From \
+                v4.0.0 onward, the `agave-unstable-api` crate feature must be specified to \
+                acknowledge use of an interface that may break without warning."
+    )
+)]
 #![allow(clippy::arithmetic_side_effects)]
 
 mod instruction_data_len;
diff --git a/runtime/Cargo.toml b/runtime/Cargo.toml
index 12f0a83c14d7ff..01987edd3332f2 100644
--- a/runtime/Cargo.toml
+++ b/runtime/Cargo.toml
@@ -17,6 +17,7 @@ crate-type = ["lib"]
 name = "solana_runtime"
 
 [features]
+agave-unstable-api = []
 dev-context-only-utils = [
     "dep:solana-system-program",
     "solana-accounts-db/dev-context-only-utils",
diff --git a/runtime/src/lib.rs b/runtime/src/lib.rs
index ded453ea3c3104..d189b6068e8835 100644
--- a/runtime/src/lib.rs
+++ b/runtime/src/lib.rs
@@ -1,3 +1,12 @@
+#![cfg_attr(
+    not(feature = "agave-unstable-api"),
+    deprecated(
+        since = "3.1.0",
+        note = "This crate has been marked for formal inclusion in the Agave Unstable API. From \
+                v4.0.0 onward, the `agave-unstable-api` crate feature must be specified to \
+                acknowledge use of an interface that may break without warning."
+    )
+)]
 #![cfg_attr(feature = "frozen-abi", feature(min_specialization))]
 #![allow(clippy::arithmetic_side_effects)]
 
diff --git a/scheduler-bindings/Cargo.toml b/scheduler-bindings/Cargo.toml
index 401d2d41e781a7..05b0235b018db4 100644
--- a/scheduler-bindings/Cargo.toml
+++ b/scheduler-bindings/Cargo.toml
@@ -9,6 +9,9 @@ homepage = { workspace = true }
 license = { workspace = true }
 edition = { workspace = true }
 
+[features]
+agave-unstable-api = []
+
 [dependencies]
 
 [lints]
diff --git a/scheduler-bindings/src/lib.rs b/scheduler-bindings/src/lib.rs
index d3c56ce8b8f396..f40383bf2f5552 100644
--- a/scheduler-bindings/src/lib.rs
+++ b/scheduler-bindings/src/lib.rs
@@ -1,3 +1,12 @@
+#![cfg_attr(
+    not(feature = "agave-unstable-api"),
+    deprecated(
+        since = "3.1.0",
+        note = "This crate has been marked for formal inclusion in the Agave Unstable API. From \
+                v4.0.0 onward, the `agave-unstable-api` crate feature must be specified to \
+                acknowledge use of an interface that may break without warning."
+    )
+)]
 #![no_std]
 
 //! Messages passed between agave and an external pack process.
diff --git a/scheduling-utils/Cargo.toml b/scheduling-utils/Cargo.toml
index 5efe6bc2559d18..ec6c566862c6e2 100644
--- a/scheduling-utils/Cargo.toml
+++ b/scheduling-utils/Cargo.toml
@@ -9,6 +9,9 @@ homepage = { workspace = true }
 license = { workspace = true }
 edition = { workspace = true }
 
+[features]
+agave-unstable-api = []
+
 [dependencies]
 agave-scheduler-bindings = { workspace = true }
 agave-transaction-view = { workspace = true }
diff --git a/scheduling-utils/src/lib.rs b/scheduling-utils/src/lib.rs
index 85dd917ced14e4..e69055b688deae 100644
--- a/scheduling-utils/src/lib.rs
+++ b/scheduling-utils/src/lib.rs
@@ -1,3 +1,12 @@
+#![cfg_attr(
+    not(feature = "agave-unstable-api"),
+    deprecated(
+        since = "3.1.0",
+        note = "This crate has been marked for formal inclusion in the Agave Unstable API. From \
+                v4.0.0 onward, the `agave-unstable-api` crate feature must be specified to \
+                acknowledge use of an interface that may break without warning."
+    )
+)]
 pub mod thread_aware_account_locks;
 
 #[cfg(unix)]
diff --git a/send-transaction-service/Cargo.toml b/send-transaction-service/Cargo.toml
index 5d23109806f354..441ced1ff11818 100644
--- a/send-transaction-service/Cargo.toml
+++ b/send-transaction-service/Cargo.toml
@@ -13,6 +13,7 @@ edition = { workspace = true }
 targets = ["x86_64-unknown-linux-gnu"]
 
 [features]
+agave-unstable-api = []
 dev-context-only-utils = ["solana-net-utils"]
 
 [dependencies]
diff --git a/send-transaction-service/src/lib.rs b/send-transaction-service/src/lib.rs
index b2c771b2384861..4222f97ebf73bd 100644
--- a/send-transaction-service/src/lib.rs
+++ b/send-transaction-service/src/lib.rs
@@ -1,3 +1,12 @@
+#![cfg_attr(
+    not(feature = "agave-unstable-api"),
+    deprecated(
+        since = "3.1.0",
+        note = "This crate has been marked for formal inclusion in the Agave Unstable API. From \
+                v4.0.0 onward, the `agave-unstable-api` crate feature must be specified to \
+                acknowledge use of an interface that may break without warning."
+    )
+)]
 #![allow(clippy::arithmetic_side_effects)]
 pub mod send_transaction_service;
 pub mod send_transaction_service_stats;
diff --git a/snapshots/Cargo.toml b/snapshots/Cargo.toml
index 8aaf28f847fcc1..265aa02af6d5d9 100644
--- a/snapshots/Cargo.toml
+++ b/snapshots/Cargo.toml
@@ -18,7 +18,6 @@ name = "agave_snapshots"
 
 [features]
 agave-unstable-api = []
-default = ["agave-unstable-api"]
 
 [dependencies]
 lz4 = { workspace = true }
diff --git a/snapshots/src/lib.rs b/snapshots/src/lib.rs
index 981a6ba521e40e..3061ac7579867c 100644
--- a/snapshots/src/lib.rs
+++ b/snapshots/src/lib.rs
@@ -1,4 +1,12 @@
-#![cfg(feature = "agave-unstable-api")]
+#![cfg_attr(
+    not(feature = "agave-unstable-api"),
+    deprecated(
+        since = "3.1.0",
+        note = "This crate has been marked for formal inclusion in the Agave Unstable API. From \
+                v4.0.0 onward, the `agave-unstable-api` crate feature must be specified to \
+                acknowledge use of an interface that may break without warning."
+    )
+)]
 
 mod archive_format;
 mod snapshot_interval;
diff --git a/storage-bigtable/Cargo.toml b/storage-bigtable/Cargo.toml
index e547d11e8dcb53..0864d17acabfb2 100644
--- a/storage-bigtable/Cargo.toml
+++ b/storage-bigtable/Cargo.toml
@@ -16,6 +16,9 @@ targets = ["x86_64-unknown-linux-gnu"]
 crate-type = ["lib"]
 name = "solana_storage_bigtable"
 
+[features]
+agave-unstable-api = []
+
 [dependencies]
 agave-reserved-account-keys = { workspace = true }
 backoff = { workspace = true, features = ["tokio"] }
diff --git a/storage-bigtable/src/lib.rs b/storage-bigtable/src/lib.rs
index 6967db5764f1b2..7c0b3aed5b5caa 100644
--- a/storage-bigtable/src/lib.rs
+++ b/storage-bigtable/src/lib.rs
@@ -1,3 +1,12 @@
+#![cfg_attr(
+    not(feature = "agave-unstable-api"),
+    deprecated(
+        since = "3.1.0",
+        note = "This crate has been marked for formal inclusion in the Agave Unstable API. From \
+                v4.0.0 onward, the `agave-unstable-api` crate feature must be specified to \
+                acknowledge use of an interface that may break without warning."
+    )
+)]
 #![allow(clippy::arithmetic_side_effects)]
 
 use {
diff --git a/storage-proto/Cargo.toml b/storage-proto/Cargo.toml
index 23f166efaa444e..80c067b8371d25 100644
--- a/storage-proto/Cargo.toml
+++ b/storage-proto/Cargo.toml
@@ -16,6 +16,9 @@ targets = ["x86_64-unknown-linux-gnu"]
 crate-type = ["lib"]
 name = "solana_storage_proto"
 
+[features]
+agave-unstable-api = []
+
 [dependencies]
 bincode = { workspace = true }
 bs58 = { workspace = true }
diff --git a/storage-proto/src/lib.rs b/storage-proto/src/lib.rs
index c76b46e1bc4b51..1997e8db59c331 100644
--- a/storage-proto/src/lib.rs
+++ b/storage-proto/src/lib.rs
@@ -1,3 +1,12 @@
+#![cfg_attr(
+    not(feature = "agave-unstable-api"),
+    deprecated(
+        since = "3.1.0",
+        note = "This crate has been marked for formal inclusion in the Agave Unstable API. From \
+                v4.0.0 onward, the `agave-unstable-api` crate feature must be specified to \
+                acknowledge use of an interface that may break without warning."
+    )
+)]
 use {
     serde::{Deserialize, Serialize},
     solana_account_decoder::{
diff --git a/streamer/Cargo.toml b/streamer/Cargo.toml
index 4a3c33a5a7c17c..bb655dbe1c1af1 100644
--- a/streamer/Cargo.toml
+++ b/streamer/Cargo.toml
@@ -17,6 +17,7 @@ crate-type = ["lib"]
 name = "solana_streamer"
 
 [features]
+agave-unstable-api = []
 dev-context-only-utils = []
 
 [dependencies]
diff --git a/streamer/src/lib.rs b/streamer/src/lib.rs
index 60ee2b753f77e3..71769499a6cacd 100644
--- a/streamer/src/lib.rs
+++ b/streamer/src/lib.rs
@@ -1,3 +1,12 @@
+#![cfg_attr(
+    not(feature = "agave-unstable-api"),
+    deprecated(
+        since = "3.1.0",
+        note = "This crate has been marked for formal inclusion in the Agave Unstable API. From \
+                v4.0.0 onward, the `agave-unstable-api` crate feature must be specified to \
+                acknowledge use of an interface that may break without warning."
+    )
+)]
 #![allow(clippy::arithmetic_side_effects)]
 pub mod evicting_sender;
 pub mod msghdr;
diff --git a/svm-callback/Cargo.toml b/svm-callback/Cargo.toml
index c24bd164467c3e..37772d763c8524 100644
--- a/svm-callback/Cargo.toml
+++ b/svm-callback/Cargo.toml
@@ -9,6 +9,9 @@ license = { workspace = true }
 edition = { workspace = true }
 readme = false
 
+[features]
+agave-unstable-api = []
+
 [dependencies]
 solana-account = { workspace = true }
 solana-clock = { workspace = true }
diff --git a/svm-callback/src/lib.rs b/svm-callback/src/lib.rs
index 57c7afa2df5a4c..b1e16e706e614d 100644
--- a/svm-callback/src/lib.rs
+++ b/svm-callback/src/lib.rs
@@ -1,3 +1,12 @@
+#![cfg_attr(
+    not(feature = "agave-unstable-api"),
+    deprecated(
+        since = "3.1.0",
+        note = "This crate has been marked for formal inclusion in the Agave Unstable API. From \
+                v4.0.0 onward, the `agave-unstable-api` crate feature must be specified to \
+                acknowledge use of an interface that may break without warning."
+    )
+)]
 use {
     solana_account::AccountSharedData, solana_clock::Slot,
     solana_precompile_error::PrecompileError, solana_pubkey::Pubkey,
diff --git a/svm-feature-set/Cargo.toml b/svm-feature-set/Cargo.toml
index c55d661d51a323..6c4b24d9022edd 100644
--- a/svm-feature-set/Cargo.toml
+++ b/svm-feature-set/Cargo.toml
@@ -9,6 +9,9 @@ license = { workspace = true }
 edition = { workspace = true }
 readme = false
 
+[features]
+agave-unstable-api = []
+
 [dependencies]
 
 [lints]
diff --git a/svm-feature-set/src/lib.rs b/svm-feature-set/src/lib.rs
index e66cd3bdc43843..9d4db9cdb57882 100644
--- a/svm-feature-set/src/lib.rs
+++ b/svm-feature-set/src/lib.rs
@@ -1,3 +1,12 @@
+#![cfg_attr(
+    not(feature = "agave-unstable-api"),
+    deprecated(
+        since = "3.1.0",
+        note = "This crate has been marked for formal inclusion in the Agave Unstable API. From \
+                v4.0.0 onward, the `agave-unstable-api` crate feature must be specified to \
+                acknowledge use of an interface that may break without warning."
+    )
+)]
 #[derive(Clone, Copy, Default)]
 pub struct SVMFeatureSet {
     pub move_precompile_verification_to_svm: bool,
diff --git a/svm-log-collector/Cargo.toml b/svm-log-collector/Cargo.toml
index 919bb386599f9b..70ee805d50fe3a 100644
--- a/svm-log-collector/Cargo.toml
+++ b/svm-log-collector/Cargo.toml
@@ -12,5 +12,8 @@ edition = { workspace = true }
 [package.metadata.docs.rs]
 targets = ["x86_64-unknown-linux-gnu"]
 
+[features]
+agave-unstable-api = []
+
 [dependencies]
 log = { workspace = true }
diff --git a/svm-log-collector/src/lib.rs b/svm-log-collector/src/lib.rs
index 612300f8e94bfc..7ae92187973ae0 100644
--- a/svm-log-collector/src/lib.rs
+++ b/svm-log-collector/src/lib.rs
@@ -1,3 +1,12 @@
+#![cfg_attr(
+    not(feature = "agave-unstable-api"),
+    deprecated(
+        since = "3.1.0",
+        note = "This crate has been marked for formal inclusion in the Agave Unstable API. From \
+                v4.0.0 onward, the `agave-unstable-api` crate feature must be specified to \
+                acknowledge use of an interface that may break without warning."
+    )
+)]
 pub use log;
 use std::{cell::RefCell, rc::Rc};
 
diff --git a/svm-measure/Cargo.toml b/svm-measure/Cargo.toml
index eee2c23b37ec6d..e415a31acd318c 100644
--- a/svm-measure/Cargo.toml
+++ b/svm-measure/Cargo.toml
@@ -11,3 +11,6 @@ edition = { workspace = true }
 
 [package.metadata.docs.rs]
 targets = ["x86_64-unknown-linux-gnu"]
+
+[features]
+agave-unstable-api = []
diff --git a/svm-measure/src/lib.rs b/svm-measure/src/lib.rs
index a1c86feb89a43f..bb34e59763af42 100644
--- a/svm-measure/src/lib.rs
+++ b/svm-measure/src/lib.rs
@@ -1,3 +1,12 @@
+#![cfg_attr(
+    not(feature = "agave-unstable-api"),
+    deprecated(
+        since = "3.1.0",
+        note = "This crate has been marked for formal inclusion in the Agave Unstable API. From \
+                v4.0.0 onward, the `agave-unstable-api` crate feature must be specified to \
+                acknowledge use of an interface that may break without warning."
+    )
+)]
 #![allow(clippy::arithmetic_side_effects)]
 pub mod macros;
 pub mod measure;
diff --git a/svm-rent-calculator/Cargo.toml b/svm-rent-calculator/Cargo.toml
index 1695328298ae47..865a67b00f410a 100644
--- a/svm-rent-calculator/Cargo.toml
+++ b/svm-rent-calculator/Cargo.toml
@@ -9,6 +9,9 @@ homepage = { workspace = true }
 license = { workspace = true }
 edition = { workspace = true }
 
+[features]
+agave-unstable-api = []
+
 [dependencies]
 solana-account = { workspace = true }
 solana-pubkey = { workspace = true }
diff --git a/svm-rent-calculator/src/lib.rs b/svm-rent-calculator/src/lib.rs
index 94277bb5bbd6f9..9287ad95fe7108 100644
--- a/svm-rent-calculator/src/lib.rs
+++ b/svm-rent-calculator/src/lib.rs
@@ -1,3 +1,11 @@
+#![cfg_attr(
+    not(feature = "agave-unstable-api"),
+    deprecated(
+        since = "3.1.0",
+        note = "This crate has been marked for formal inclusion in the Agave Unstable \
+        API. From v4.0.0 onward, the `agave-unstable-api` crate feature must be specified \
+        to acknowledge use of an interface that may break without warning."
+))]
 //! Solana SVM Rent Calculator.
 //!
 //! Rent management for SVM.
diff --git a/svm-timings/Cargo.toml b/svm-timings/Cargo.toml
index c0a59118777917..84e0a071d39f33 100644
--- a/svm-timings/Cargo.toml
+++ b/svm-timings/Cargo.toml
@@ -12,6 +12,9 @@ edition = { workspace = true }
 [package.metadata.docs.rs]
 targets = ["x86_64-unknown-linux-gnu"]
 
+[features]
+agave-unstable-api = []
+
 [dependencies]
 eager = { workspace = true }
 enum-iterator = { workspace = true }
diff --git a/svm-timings/src/lib.rs b/svm-timings/src/lib.rs
index 8032fa9c73ad73..98515fe04760cd 100644
--- a/svm-timings/src/lib.rs
+++ b/svm-timings/src/lib.rs
@@ -1,3 +1,12 @@
+#![cfg_attr(
+    not(feature = "agave-unstable-api"),
+    deprecated(
+        since = "3.1.0",
+        note = "This crate has been marked for formal inclusion in the Agave Unstable API. From \
+                v4.0.0 onward, the `agave-unstable-api` crate feature must be specified to \
+                acknowledge use of an interface that may break without warning."
+    )
+)]
 #[macro_use]
 extern crate eager;
 use {
diff --git a/svm-transaction/Cargo.toml b/svm-transaction/Cargo.toml
index 629b788584b185..0fa69fa858ad9e 100644
--- a/svm-transaction/Cargo.toml
+++ b/svm-transaction/Cargo.toml
@@ -9,6 +9,9 @@ homepage = { workspace = true }
 license = { workspace = true }
 edition = { workspace = true }
 
+[features]
+agave-unstable-api = []
+
 [dependencies]
 solana-hash = { workspace = true }
 solana-message = { workspace = true }
diff --git a/svm-transaction/src/lib.rs b/svm-transaction/src/lib.rs
index 1929f2e634d58e..532205262cb08c 100644
--- a/svm-transaction/src/lib.rs
+++ b/svm-transaction/src/lib.rs
@@ -1,3 +1,12 @@
+#![cfg_attr(
+    not(feature = "agave-unstable-api"),
+    deprecated(
+        since = "3.1.0",
+        note = "This crate has been marked for formal inclusion in the Agave Unstable API. From \
+                v4.0.0 onward, the `agave-unstable-api` crate feature must be specified to \
+                acknowledge use of an interface that may break without warning."
+    )
+)]
 pub mod instruction;
 pub mod message_address_table_lookup;
 pub mod svm_message;
diff --git a/svm-type-overrides/Cargo.toml b/svm-type-overrides/Cargo.toml
index 1159c6b6ae8d6b..93a70c79b0ffd7 100644
--- a/svm-type-overrides/Cargo.toml
+++ b/svm-type-overrides/Cargo.toml
@@ -9,6 +9,7 @@ license = { workspace = true }
 edition = { workspace = true }
 
 [features]
+agave-unstable-api = []
 shuttle-test = ["dep:shuttle"]
 executor = ["dep:futures"]
 
diff --git a/svm-type-overrides/src/lib.rs b/svm-type-overrides/src/lib.rs
index c6573956336943..c35cd4f99f96cb 100644
--- a/svm-type-overrides/src/lib.rs
+++ b/svm-type-overrides/src/lib.rs
@@ -1,3 +1,12 @@
+#![cfg_attr(
+    not(feature = "agave-unstable-api"),
+    deprecated(
+        since = "3.1.0",
+        note = "This crate has been marked for formal inclusion in the Agave Unstable API. From \
+                v4.0.0 onward, the `agave-unstable-api` crate feature must be specified to \
+                acknowledge use of an interface that may break without warning."
+    )
+)]
 //! This lib contains both standard imports and imports shuttle.
 //! Shuttle is a Rust crate that facilitates multithreaded testing. It has its own scheduler
 //! and can efficiently detect bugs in concurrent code. The downside is that we need to replace
diff --git a/svm/Cargo.toml b/svm/Cargo.toml
index c31eee29231e95..b5593f009e6049 100644
--- a/svm/Cargo.toml
+++ b/svm/Cargo.toml
@@ -17,6 +17,7 @@ crate-type = ["lib"]
 name = "solana_svm"
 
 [features]
+agave-unstable-api = []
 dev-context-only-utils = [
     "dep:qualifier_attr",
     "solana-program-runtime/dev-context-only-utils",
diff --git a/svm/src/lib.rs b/svm/src/lib.rs
index f6f018938ebc80..c8aba822a3ac5a 100644
--- a/svm/src/lib.rs
+++ b/svm/src/lib.rs
@@ -1,3 +1,12 @@
+#![cfg_attr(
+    not(feature = "agave-unstable-api"),
+    deprecated(
+        since = "3.1.0",
+        note = "This crate has been marked for formal inclusion in the Agave Unstable API. From \
+                v4.0.0 onward, the `agave-unstable-api` crate feature must be specified to \
+                acknowledge use of an interface that may break without warning."
+    )
+)]
 #![cfg_attr(feature = "frozen-abi", feature(min_specialization))]
 #![allow(clippy::arithmetic_side_effects)]
 
diff --git a/syscalls/Cargo.toml b/syscalls/Cargo.toml
index 55758f2e632555..73f1d90fe12668 100644
--- a/syscalls/Cargo.toml
+++ b/syscalls/Cargo.toml
@@ -14,6 +14,7 @@ targets = ["x86_64-unknown-linux-gnu"]
 
 [features]
 default = ["metrics"]
+agave-unstable-api = []
 metrics = ["solana-program-runtime/metrics"]
 shuttle-test = [
     "solana-program-runtime/shuttle-test",
diff --git a/syscalls/src/lib.rs b/syscalls/src/lib.rs
index 323367ac8f5ccc..0c01b2da4157b2 100644
--- a/syscalls/src/lib.rs
+++ b/syscalls/src/lib.rs
@@ -1,3 +1,12 @@
+#![cfg_attr(
+    not(feature = "agave-unstable-api"),
+    deprecated(
+        since = "3.1.0",
+        note = "This crate has been marked for formal inclusion in the Agave Unstable API. From \
+                v4.0.0 onward, the `agave-unstable-api` crate feature must be specified to \
+                acknowledge use of an interface that may break without warning."
+    )
+)]
 pub use self::{
     cpi::{SyscallInvokeSignedC, SyscallInvokeSignedRust},
     logging::{
diff --git a/thread-manager/Cargo.toml b/thread-manager/Cargo.toml
index 1482012b578bfd..2a09aec5651883 100644
--- a/thread-manager/Cargo.toml
+++ b/thread-manager/Cargo.toml
@@ -10,6 +10,7 @@ license = { workspace = true }
 edition = { workspace = true }
 
 [features]
+agave-unstable-api = []
 dev-context-only-utils = []
 
 [dependencies]
@@ -27,7 +28,7 @@ tokio = { workspace = true, features = ["time", "rt-multi-thread"] }
 affinity = "0.1.2"
 
 [dev-dependencies]
-agave-thread-manager = { path = ".", features = ["dev-context-only-utils"] }
+agave-thread-manager = { path = ".", features = ["agave-unstable-api", "dev-context-only-utils"] }
 axum = { workspace = true }
 env_logger = { workspace = true }
 hyper = { workspace = true, features = ["http1", "client", "stream", "tcp"] }
diff --git a/thread-manager/src/lib.rs b/thread-manager/src/lib.rs
index 3b120d7b4b7588..3ad426c30f27a0 100644
--- a/thread-manager/src/lib.rs
+++ b/thread-manager/src/lib.rs
@@ -1,3 +1,12 @@
+#![cfg_attr(
+    not(feature = "agave-unstable-api"),
+    deprecated(
+        since = "3.1.0",
+        note = "This crate has been marked for formal inclusion in the Agave Unstable API. From \
+                v4.0.0 onward, the `agave-unstable-api` crate feature must be specified to \
+                acknowledge use of an interface that may break without warning."
+    )
+)]
 use {
     anyhow::Ok,
     serde::{Deserialize, Serialize},
diff --git a/tls-utils/Cargo.toml b/tls-utils/Cargo.toml
index a77bb65b1994a5..6afd2b351f3a12 100644
--- a/tls-utils/Cargo.toml
+++ b/tls-utils/Cargo.toml
@@ -9,6 +9,9 @@ homepage = { workspace = true }
 license = { workspace = true }
 edition = { workspace = true }
 
+[features]
+agave-unstable-api = []
+
 [dependencies]
 rustls = { workspace = true, features = ["ring"] }
 solana-keypair = { workspace = true }
diff --git a/tls-utils/src/lib.rs b/tls-utils/src/lib.rs
index 3f20152cc894a0..d61c22e8f8c0e3 100644
--- a/tls-utils/src/lib.rs
+++ b/tls-utils/src/lib.rs
@@ -1,3 +1,12 @@
+#![cfg_attr(
+    not(feature = "agave-unstable-api"),
+    deprecated(
+        since = "3.1.0",
+        note = "This crate has been marked for formal inclusion in the Agave Unstable API. From \
+                v4.0.0 onward, the `agave-unstable-api` crate feature must be specified to \
+                acknowledge use of an interface that may break without warning."
+    )
+)]
 //! Collection of TLS related code fragments that end up popping up everywhere where quic is used.
 //! Aggregated here to avoid bugs due to conflicting implementations of the same functionality.
 
diff --git a/tps-client/Cargo.toml b/tps-client/Cargo.toml
index f3a98454d4f9a4..8d8ffbf10cf075 100644
--- a/tps-client/Cargo.toml
+++ b/tps-client/Cargo.toml
@@ -14,6 +14,7 @@ all-features = true
 rustdoc-args = ["--cfg=docsrs"]
 
 [features]
+agave-unstable-api = []
 bank-client = ["dep:solana-client-traits", "dep:solana-runtime"]
 dev-context-only-utils = []
 
diff --git a/tps-client/src/lib.rs b/tps-client/src/lib.rs
index c1d0fd601fd9d1..27e4df9c5fd1d7 100644
--- a/tps-client/src/lib.rs
+++ b/tps-client/src/lib.rs
@@ -1,3 +1,12 @@
+#![cfg_attr(
+    not(feature = "agave-unstable-api"),
+    deprecated(
+        since = "3.1.0",
+        note = "This crate has been marked for formal inclusion in the Agave Unstable API. From \
+                v4.0.0 onward, the `agave-unstable-api` crate feature must be specified to \
+                acknowledge use of an interface that may break without warning."
+    )
+)]
 #![cfg_attr(docsrs, feature(doc_auto_cfg))]
 use {
     log::debug,
diff --git a/tpu-client-next/Cargo.toml b/tpu-client-next/Cargo.toml
index fa3c61316fcd3e..6bae9f2c77b7dd 100644
--- a/tpu-client-next/Cargo.toml
+++ b/tpu-client-next/Cargo.toml
@@ -12,8 +12,8 @@ edition = { workspace = true }
 targets = ["x86_64-unknown-linux-gnu"]
 
 [features]
-agave-unstable-api = ["dep:qualifier_attr"]
 default = ["log"]
+agave-unstable-api = []
 log = ["dep:log"]
 metrics = ["dep:solana-metrics"]
 tracing = ["dep:tracing"]
@@ -22,7 +22,6 @@ tracing = ["dep:tracing"]
 async-trait = { workspace = true }
 log = { workspace = true, optional = true }
 lru = { workspace = true }
-qualifier_attr = { workspace = true, optional = true }
 quinn = { workspace = true }
 rustls = { workspace = true }
 solana-clock = { workspace = true }
diff --git a/tpu-client-next/src/connection_workers_scheduler.rs b/tpu-client-next/src/connection_workers_scheduler.rs
index 7097e40bcb2b12..af5b75bd3af202 100644
--- a/tpu-client-next/src/connection_workers_scheduler.rs
+++ b/tpu-client-next/src/connection_workers_scheduler.rs
@@ -2,7 +2,6 @@
 //! to the upcoming leaders.
 
 #[cfg(feature = "agave-unstable-api")]
-use qualifier_attr::qualifiers;
 use {
     super::leader_updater::LeaderUpdater,
     crate::{
@@ -305,7 +304,6 @@ impl ConnectionWorkersScheduler {
 }
 
 /// Sets up the QUIC endpoint for the scheduler to handle connections.
-#[cfg_attr(feature = "agave-unstable-api", qualifiers(pub))]
 fn setup_endpoint(
     bind: BindTarget,
     stake_identity: Option<StakeIdentity>,
@@ -366,7 +364,6 @@ impl WorkersBroadcaster for NonblockingBroadcaster {
 ///
 /// This function selects up to `send_fanout` addresses from the `leaders` list, ensuring that
 /// only unique addresses are included while maintaining their original order.
-#[cfg_attr(feature = "agave-unstable-api", qualifiers(pub))]
 pub fn extract_send_leaders(leaders: &[SocketAddr], send_fanout: usize) -> Vec<SocketAddr> {
     let send_count = send_fanout.min(leaders.len());
     remove_duplicates(&leaders[..send_count])
diff --git a/tpu-client-next/src/lib.rs b/tpu-client-next/src/lib.rs
index 4bb09c91c67932..7f2dc19c85dccd 100644
--- a/tpu-client-next/src/lib.rs
+++ b/tpu-client-next/src/lib.rs
@@ -1,3 +1,12 @@
+#![cfg_attr(
+    not(feature = "agave-unstable-api"),
+    deprecated(
+        since = "3.1.0",
+        note = "This crate has been marked for formal inclusion in the Agave Unstable API. From \
+                v4.0.0 onward, the `agave-unstable-api` crate feature must be specified to \
+                acknowledge use of an interface that may break without warning."
+    )
+)]
 //! # Feature flags
 //!
 //! Tpu-client-next supports three features:
diff --git a/tpu-client-next/src/workers_cache.rs b/tpu-client-next/src/workers_cache.rs
index 838ceecd07623c..7b4abcb3518b9a 100644
--- a/tpu-client-next/src/workers_cache.rs
+++ b/tpu-client-next/src/workers_cache.rs
@@ -3,7 +3,6 @@
 //! batches, and gathering send transaction statistics.
 
 #[cfg(feature = "agave-unstable-api")]
-use qualifier_attr::qualifiers;
 use {
     crate::{
         connection_worker::ConnectionWorker,
@@ -81,7 +80,6 @@ impl WorkerInfo {
 }
 
 /// Spawns a worker to handle communication with a given peer.
-#[cfg_attr(feature = "agave-unstable-api", qualifiers(pub))]
 pub(crate) fn spawn_worker(
     endpoint: &Endpoint,
     peer: &SocketAddr,
@@ -141,7 +139,6 @@ pub enum WorkersCacheError {
 }
 
 impl WorkersCache {
-    #[cfg_attr(feature = "agave-unstable-api", qualifiers(pub))]
     pub(crate) fn new(capacity: usize, cancel: CancellationToken) -> Self {
         Self {
             workers: LruCache::new(capacity),
@@ -155,7 +152,6 @@ impl WorkersCache {
         self.workers.contains(peer)
     }
 
-    #[cfg_attr(feature = "agave-unstable-api", qualifiers(pub))]
     pub(crate) fn push(
         &mut self,
         leader: SocketAddr,
@@ -320,7 +316,6 @@ impl WorkersCache {
     ///
     /// The method awaits the completion of all shutdown tasks, ensuring that
     /// each worker is properly terminated.
-    #[cfg_attr(feature = "agave-unstable-api", qualifiers(pub))]
     pub(crate) async fn shutdown(&mut self) {
         // Interrupt any outstanding `send_transactions()` calls.
         self.cancel.cancel();
diff --git a/tpu-client/Cargo.toml b/tpu-client/Cargo.toml
index ec06baa4063942..539c9a4fe108dc 100644
--- a/tpu-client/Cargo.toml
+++ b/tpu-client/Cargo.toml
@@ -14,6 +14,7 @@ targets = ["x86_64-unknown-linux-gnu"]
 
 [features]
 default = ["spinner"]
+agave-unstable-api = []
 # Support tpu-client methods that feature a spinner progress bar for
 # command-line interfaces
 spinner = [
diff --git a/tpu-client/src/lib.rs b/tpu-client/src/lib.rs
index db01a6f0bb4635..d43b681ea86e83 100644
--- a/tpu-client/src/lib.rs
+++ b/tpu-client/src/lib.rs
@@ -1,3 +1,12 @@
+#![cfg_attr(
+    not(feature = "agave-unstable-api"),
+    deprecated(
+        since = "3.1.0",
+        note = "This crate has been marked for formal inclusion in the Agave Unstable API. From \
+                v4.0.0 onward, the `agave-unstable-api` crate feature must be specified to \
+                acknowledge use of an interface that may break without warning."
+    )
+)]
 #![allow(clippy::arithmetic_side_effects)]
 
 pub mod nonblocking;
diff --git a/transaction-context/Cargo.toml b/transaction-context/Cargo.toml
index c5c1d21eef607e..4bc4c5fed630f6 100644
--- a/transaction-context/Cargo.toml
+++ b/transaction-context/Cargo.toml
@@ -15,6 +15,7 @@ all-features = true
 rustdoc-args = ["--cfg=docsrs"]
 
 [features]
+agave-unstable-api = []
 bincode = ["dep:bincode", "serde", "solana-account/bincode"]
 dev-context-only-utils = ["bincode", "solana-account/dev-context-only-utils", "dep:qualifier_attr"]
 serde = ["serde/derive"]
diff --git a/transaction-context/src/lib.rs b/transaction-context/src/lib.rs
index 1ff1da08d3b46a..cc6e4206f1922b 100644
--- a/transaction-context/src/lib.rs
+++ b/transaction-context/src/lib.rs
@@ -1,3 +1,12 @@
+#![cfg_attr(
+    not(feature = "agave-unstable-api"),
+    deprecated(
+        since = "3.1.0",
+        note = "This crate has been marked for formal inclusion in the Agave Unstable API. From \
+                v4.0.0 onward, the `agave-unstable-api` crate feature must be specified to \
+                acknowledge use of an interface that may break without warning."
+    )
+)]
 //! Data shared between program runtime and built-in programs as well as SBF programs.
 #![deny(clippy::indexing_slicing)]
 #![cfg_attr(docsrs, feature(doc_auto_cfg))]
diff --git a/transaction-metrics-tracker/Cargo.toml b/transaction-metrics-tracker/Cargo.toml
index 74c897122a38dd..80df945fb076c3 100644
--- a/transaction-metrics-tracker/Cargo.toml
+++ b/transaction-metrics-tracker/Cargo.toml
@@ -12,6 +12,9 @@ edition = { workspace = true }
 [package.metadata.docs.rs]
 targets = ["x86_64-unknown-linux-gnu"]
 
+[features]
+agave-unstable-api = []
+
 [dependencies]
 base64 = { workspace = true }
 bincode = { workspace = true }
diff --git a/transaction-metrics-tracker/src/lib.rs b/transaction-metrics-tracker/src/lib.rs
index c9c3a5d5b4ef4b..a8255f17fb6f97 100644
--- a/transaction-metrics-tracker/src/lib.rs
+++ b/transaction-metrics-tracker/src/lib.rs
@@ -1,3 +1,12 @@
+#![cfg_attr(
+    not(feature = "agave-unstable-api"),
+    deprecated(
+        since = "3.1.0",
+        note = "This crate has been marked for formal inclusion in the Agave Unstable API. From \
+                v4.0.0 onward, the `agave-unstable-api` crate feature must be specified to \
+                acknowledge use of an interface that may break without warning."
+    )
+)]
 use {
     log::*,
     rand::Rng,
diff --git a/transaction-status-client-types/Cargo.toml b/transaction-status-client-types/Cargo.toml
index e3bda10e8182d6..51a7d197eddc04 100644
--- a/transaction-status-client-types/Cargo.toml
+++ b/transaction-status-client-types/Cargo.toml
@@ -12,6 +12,9 @@ edition = { workspace = true }
 [package.metadata.docs.rs]
 targets = ["x86_64-unknown-linux-gnu"]
 
+[features]
+agave-unstable-api = []
+
 [dependencies]
 base64 = { workspace = true }
 bincode = { workspace = true }
diff --git a/transaction-status-client-types/src/lib.rs b/transaction-status-client-types/src/lib.rs
index fdc68324e746e0..e7f62ad2ebfa07 100644
--- a/transaction-status-client-types/src/lib.rs
+++ b/transaction-status-client-types/src/lib.rs
@@ -1,3 +1,12 @@
+#![cfg_attr(
+    not(feature = "agave-unstable-api"),
+    deprecated(
+        since = "3.1.0",
+        note = "This crate has been marked for formal inclusion in the Agave Unstable API. From \
+                v4.0.0 onward, the `agave-unstable-api` crate feature must be specified to \
+                acknowledge use of an interface that may break without warning."
+    )
+)]
 //! Core types for solana-transaction-status
 use {
     crate::option_serializer::OptionSerializer,
diff --git a/transaction-status/Cargo.toml b/transaction-status/Cargo.toml
index fe56bc13ac7c28..d1b05ac65527e7 100644
--- a/transaction-status/Cargo.toml
+++ b/transaction-status/Cargo.toml
@@ -12,6 +12,9 @@ edition = { workspace = true }
 [package.metadata.docs.rs]
 targets = ["x86_64-unknown-linux-gnu"]
 
+[features]
+agave-unstable-api = []
+
 [dependencies]
 Inflector = { workspace = true }
 agave-reserved-account-keys = { workspace = true }
diff --git a/transaction-status/src/lib.rs b/transaction-status/src/lib.rs
index f1afd1eb73961c..d0dd451f8cc8e1 100644
--- a/transaction-status/src/lib.rs
+++ b/transaction-status/src/lib.rs
@@ -1,3 +1,12 @@
+#![cfg_attr(
+    not(feature = "agave-unstable-api"),
+    deprecated(
+        since = "3.1.0",
+        note = "This crate has been marked for formal inclusion in the Agave Unstable API. From \
+                v4.0.0 onward, the `agave-unstable-api` crate feature must be specified to \
+                acknowledge use of an interface that may break without warning."
+    )
+)]
 #![allow(clippy::arithmetic_side_effects)]
 
 pub use {
diff --git a/transaction-view/Cargo.toml b/transaction-view/Cargo.toml
index 8216725548ea45..3c64ae7baf7cc0 100644
--- a/transaction-view/Cargo.toml
+++ b/transaction-view/Cargo.toml
@@ -10,6 +10,7 @@ license = { workspace = true }
 edition = { workspace = true }
 
 [features]
+agave-unstable-api = []
 dev-context-only-utils = []
 
 [dependencies]
diff --git a/transaction-view/src/lib.rs b/transaction-view/src/lib.rs
index 025b6ed8130e49..41ba02d61bf763 100644
--- a/transaction-view/src/lib.rs
+++ b/transaction-view/src/lib.rs
@@ -1,3 +1,12 @@
+#![cfg_attr(
+    not(feature = "agave-unstable-api"),
+    deprecated(
+        since = "3.1.0",
+        note = "This crate has been marked for formal inclusion in the Agave Unstable API. From \
+                v4.0.0 onward, the `agave-unstable-api` crate feature must be specified to \
+                acknowledge use of an interface that may break without warning."
+    )
+)]
 // Parsing helpers only need to be public for benchmarks.
 #[cfg(feature = "dev-context-only-utils")]
 pub mod bytes;
diff --git a/turbine/src/lib.rs b/turbine/src/lib.rs
index 50c68d15e98dd3..f716c6153e7d34 100644
--- a/turbine/src/lib.rs
+++ b/turbine/src/lib.rs
@@ -1,31 +1,31 @@
+#![cfg_attr(
+    not(feature = "agave-unstable-api"),
+    deprecated(
+        since = "3.1.0",
+        note = "This crate has been marked for formal inclusion in the Agave Unstable API. From \
+                v4.0.0 onward, the `agave-unstable-api` crate feature must be specified to \
+                acknowledge use of an interface that may break without warning."
+    )
+)]
 #![allow(clippy::arithmetic_side_effects)]
 
-#[cfg(feature = "agave-unstable-api")]
 mod addr_cache;
 
-#[cfg(feature = "agave-unstable-api")]
 pub mod broadcast_stage;
 
-#[cfg(feature = "agave-unstable-api")]
 pub mod cluster_nodes;
 
-#[cfg(feature = "agave-unstable-api")]
 pub mod quic_endpoint;
 
-#[cfg(feature = "agave-unstable-api")]
 pub mod retransmit_stage;
 
-#[cfg(feature = "agave-unstable-api")]
 pub mod sigverify_shreds;
 
-#[cfg(feature = "agave-unstable-api")]
 pub mod xdp;
 
-#[cfg(feature = "agave-unstable-api")]
 #[macro_use]
 extern crate log;
 
-#[cfg(feature = "agave-unstable-api")]
 #[macro_use]
 extern crate solana_metrics;
 
diff --git a/udp-client/Cargo.toml b/udp-client/Cargo.toml
index da2da691cfaf85..09a6960da7e0d9 100644
--- a/udp-client/Cargo.toml
+++ b/udp-client/Cargo.toml
@@ -10,6 +10,7 @@ license = { workspace = true }
 edition = { workspace = true }
 
 [features]
+agave-unstable-api = []
 dev-context-only-utils = []
 
 [dependencies]
diff --git a/udp-client/src/lib.rs b/udp-client/src/lib.rs
index 163af3043724e0..10de3b62dadcd0 100644
--- a/udp-client/src/lib.rs
+++ b/udp-client/src/lib.rs
@@ -1,3 +1,12 @@
+#![cfg_attr(
+    not(feature = "agave-unstable-api"),
+    deprecated(
+        since = "3.1.0",
+        note = "This crate has been marked for formal inclusion in the Agave Unstable API. From \
+                v4.0.0 onward, the `agave-unstable-api` crate feature must be specified to \
+                acknowledge use of an interface that may break without warning."
+    )
+)]
 #![allow(clippy::arithmetic_side_effects)]
 
 pub mod nonblocking;
diff --git a/unified-scheduler-logic/Cargo.toml b/unified-scheduler-logic/Cargo.toml
index 6fd5ef891eb40a..50cebd556ec437 100644
--- a/unified-scheduler-logic/Cargo.toml
+++ b/unified-scheduler-logic/Cargo.toml
@@ -9,6 +9,9 @@ homepage = { workspace = true }
 license = { workspace = true }
 edition = { workspace = true }
 
+[features]
+agave-unstable-api = []
+
 [dependencies]
 assert_matches = { workspace = true }
 solana-pubkey = { workspace = true }
diff --git a/unified-scheduler-logic/src/lib.rs b/unified-scheduler-logic/src/lib.rs
index cc09b5ce6ff23c..cbc1d69667570a 100644
--- a/unified-scheduler-logic/src/lib.rs
+++ b/unified-scheduler-logic/src/lib.rs
@@ -1,3 +1,12 @@
+#![cfg_attr(
+    not(feature = "agave-unstable-api"),
+    deprecated(
+        since = "3.1.0",
+        note = "This crate has been marked for formal inclusion in the Agave Unstable API. From \
+                v4.0.0 onward, the `agave-unstable-api` crate feature must be specified to \
+                acknowledge use of an interface that may break without warning."
+    )
+)]
 #![allow(rustdoc::private_intra_doc_links)]
 //! The task (transaction) scheduling code for the unified scheduler
 //!
diff --git a/unified-scheduler-pool/Cargo.toml b/unified-scheduler-pool/Cargo.toml
index 4996870ea4c90e..359c1e43434b6c 100644
--- a/unified-scheduler-pool/Cargo.toml
+++ b/unified-scheduler-pool/Cargo.toml
@@ -10,6 +10,7 @@ license = { workspace = true }
 edition = { workspace = true }
 
 [features]
+agave-unstable-api = []
 dev-context-only-utils = []
 
 [dependencies]
diff --git a/unified-scheduler-pool/src/lib.rs b/unified-scheduler-pool/src/lib.rs
index d92b7eb82b470f..c617e54de2f825 100644
--- a/unified-scheduler-pool/src/lib.rs
+++ b/unified-scheduler-pool/src/lib.rs
@@ -1,3 +1,12 @@
+#![cfg_attr(
+    not(feature = "agave-unstable-api"),
+    deprecated(
+        since = "3.1.0",
+        note = "This crate has been marked for formal inclusion in the Agave Unstable API. From \
+                v4.0.0 onward, the `agave-unstable-api` crate feature must be specified to \
+                acknowledge use of an interface that may break without warning."
+    )
+)]
 //! Transaction scheduling code.
 //!
 //! This crate implements 3 solana-runtime traits [`InstalledScheduler`], [`UninstalledScheduler`]
diff --git a/verified-packet-receiver/Cargo.toml b/verified-packet-receiver/Cargo.toml
index 166a0fc0497252..673d797e99c5fc 100644
--- a/verified-packet-receiver/Cargo.toml
+++ b/verified-packet-receiver/Cargo.toml
@@ -17,6 +17,9 @@ targets = ["x86_64-unknown-linux-gnu"]
 crate-type = ["lib"]
 name = "agave_verified_packet_receiver"
 
+[features]
+agave-unstable-api = []
+
 [dependencies]
 solana-perf = { workspace = true }
 solana-streamer = { workspace = true }
diff --git a/verified-packet-receiver/src/lib.rs b/verified-packet-receiver/src/lib.rs
index 4c0db7eaa35a61..b3e715e3b56740 100644
--- a/verified-packet-receiver/src/lib.rs
+++ b/verified-packet-receiver/src/lib.rs
@@ -1 +1,10 @@
+#![cfg_attr(
+    not(feature = "agave-unstable-api"),
+    deprecated(
+        since = "3.1.0",
+        note = "This crate has been marked for formal inclusion in the Agave Unstable API. From \
+                v4.0.0 onward, the `agave-unstable-api` crate feature must be specified to \
+                acknowledge use of an interface that may break without warning."
+    )
+)]
 pub mod receiver;
diff --git a/version/Cargo.toml b/version/Cargo.toml
index 9033498dffdd11..aa5b17e372a984 100644
--- a/version/Cargo.toml
+++ b/version/Cargo.toml
@@ -16,6 +16,7 @@ targets = ["x86_64-unknown-linux-gnu"]
 name = "solana_version"
 
 [features]
+agave-unstable-api = []
 dummy-for-ci-check = []
 frozen-abi = ["dep:solana-frozen-abi", "dep:solana-frozen-abi-macro"]
 
diff --git a/version/src/lib.rs b/version/src/lib.rs
index 4b6f6528ef9593..138e9ce6f1dd58 100644
--- a/version/src/lib.rs
+++ b/version/src/lib.rs
@@ -1,3 +1,12 @@
+#![cfg_attr(
+    not(feature = "agave-unstable-api"),
+    deprecated(
+        since = "3.1.0",
+        note = "This crate has been marked for formal inclusion in the Agave Unstable API. From \
+                v4.0.0 onward, the `agave-unstable-api` crate feature must be specified to \
+                acknowledge use of an interface that may break without warning."
+    )
+)]
 #![cfg_attr(feature = "frozen-abi", feature(min_specialization))]
 
 pub use self::legacy::{LegacyVersion1, LegacyVersion2};
diff --git a/vortexor/Cargo.toml b/vortexor/Cargo.toml
index e2afbc9339cd5c..83cf237331eeca 100644
--- a/vortexor/Cargo.toml
+++ b/vortexor/Cargo.toml
@@ -19,6 +19,8 @@ crate-type = ["lib"]
 name = "solana_vortexor"
 
 [features]
+default = ["agave-unstable-api"]
+agave-unstable-api = []
 dev-context-only-utils = []
 
 [dependencies]
diff --git a/vortexor/src/lib.rs b/vortexor/src/lib.rs
index 3434b9cdcc00ec..104fb15052da3e 100644
--- a/vortexor/src/lib.rs
+++ b/vortexor/src/lib.rs
@@ -1,3 +1,12 @@
+#![cfg_attr(
+    not(feature = "agave-unstable-api"),
+    deprecated(
+        since = "3.1.0",
+        note = "This crate has been marked for formal inclusion in the Agave Unstable API. From \
+                v4.0.0 onward, the `agave-unstable-api` crate feature must be specified to \
+                acknowledge use of an interface that may break without warning."
+    )
+)]
 pub mod cli;
 pub mod rpc_load_balancer;
 pub mod sender;
diff --git a/vote/Cargo.toml b/vote/Cargo.toml
index 9758222ec0391b..243d7f1c002dc9 100644
--- a/vote/Cargo.toml
+++ b/vote/Cargo.toml
@@ -17,6 +17,7 @@ crate-type = ["lib"]
 name = "solana_vote"
 
 [features]
+agave-unstable-api = []
 dev-context-only-utils = ["dep:rand", "dep:bincode"]
 frozen-abi = ["dep:solana-frozen-abi", "dep:solana-frozen-abi-macro"]
 
diff --git a/vote/src/lib.rs b/vote/src/lib.rs
index 62672bc5c3436d..8131e5204f837e 100644
--- a/vote/src/lib.rs
+++ b/vote/src/lib.rs
@@ -1,3 +1,12 @@
+#![cfg_attr(
+    not(feature = "agave-unstable-api"),
+    deprecated(
+        since = "3.1.0",
+        note = "This crate has been marked for formal inclusion in the Agave Unstable API. From \
+                v4.0.0 onward, the `agave-unstable-api` crate feature must be specified to \
+                acknowledge use of an interface that may break without warning."
+    )
+)]
 #![cfg_attr(feature = "frozen-abi", feature(min_specialization))]
 #![allow(clippy::arithmetic_side_effects)]
 
diff --git a/votor-messages/Cargo.toml b/votor-messages/Cargo.toml
index 5ebb07474b4a87..57d6185dcb1a08 100644
--- a/votor-messages/Cargo.toml
+++ b/votor-messages/Cargo.toml
@@ -10,6 +10,7 @@ license = { workspace = true }
 edition = { workspace = true }
 
 [features]
+agave-unstable-api = []
 frozen-abi = ["dep:solana-frozen-abi", "dep:solana-frozen-abi-macro"]
 
 [dependencies]
diff --git a/votor-messages/src/lib.rs b/votor-messages/src/lib.rs
index ba2ee9995d3c7c..1b99a92566d014 100644
--- a/votor-messages/src/lib.rs
+++ b/votor-messages/src/lib.rs
@@ -1,3 +1,12 @@
+#![cfg_attr(
+    not(feature = "agave-unstable-api"),
+    deprecated(
+        since = "3.1.0",
+        note = "This crate has been marked for formal inclusion in the Agave Unstable API. From \
+                v4.0.0 onward, the `agave-unstable-api` crate feature must be specified to \
+                acknowledge use of an interface that may break without warning."
+    )
+)]
 //! Alpenglow vote message types
 #![cfg_attr(feature = "frozen-abi", feature(min_specialization))]
 #![deny(missing_docs)]
diff --git a/votor/Cargo.toml b/votor/Cargo.toml
index 2fc2fec1f0a5cb..a447123974ec7f 100644
--- a/votor/Cargo.toml
+++ b/votor/Cargo.toml
@@ -11,7 +11,6 @@ edition = { workspace = true }
 
 [features]
 agave-unstable-api = []
-default = ["agave-unstable-api"]
 dev-context-only-utils = ["solana-runtime/dev-context-only-utils"]
 frozen-abi = [
     "dep:solana-frozen-abi",
diff --git a/votor/src/lib.rs b/votor/src/lib.rs
index 57b664116ba66d..c285e0e8a8bdb3 100644
--- a/votor/src/lib.rs
+++ b/votor/src/lib.rs
@@ -1,4 +1,12 @@
-#![cfg(feature = "agave-unstable-api")]
+#![cfg_attr(
+    not(feature = "agave-unstable-api"),
+    deprecated(
+        since = "3.1.0",
+        note = "This crate has been marked for formal inclusion in the Agave Unstable API. From \
+                v4.0.0 onward, the `agave-unstable-api` crate feature must be specified to \
+                acknowledge use of an interface that may break without warning."
+    )
+)]
 #![cfg_attr(feature = "frozen-abi", feature(min_specialization))]
 
 #[macro_use]
diff --git a/wen-restart/Cargo.toml b/wen-restart/Cargo.toml
index 10862793309512..ed73f1f74408d6 100644
--- a/wen-restart/Cargo.toml
+++ b/wen-restart/Cargo.toml
@@ -16,6 +16,9 @@ targets = ["x86_64-unknown-linux-gnu"]
 [lib]
 name = "solana_wen_restart"
 
+[features]
+agave-unstable-api = []
+
 [dependencies]
 anyhow = { workspace = true }
 log = { workspace = true }
diff --git a/wen-restart/src/lib.rs b/wen-restart/src/lib.rs
index d798cae1313ef4..ff357baa182e74 100644
--- a/wen-restart/src/lib.rs
+++ b/wen-restart/src/lib.rs
@@ -1,3 +1,12 @@
+#![cfg_attr(
+    not(feature = "agave-unstable-api"),
+    deprecated(
+        since = "3.1.0",
+        note = "This crate has been marked for formal inclusion in the Agave Unstable API. From \
+                v4.0.0 onward, the `agave-unstable-api` crate feature must be specified to \
+                acknowledge use of an interface that may break without warning."
+    )
+)]
 pub(crate) mod solana {
     pub(crate) mod wen_restart_proto {
         include!(concat!(env!("OUT_DIR"), "/solana.wen_restart_proto.rs"));
diff --git a/xdp/Cargo.toml b/xdp/Cargo.toml
index e68455291f536a..41016b30f5de15 100644
--- a/xdp/Cargo.toml
+++ b/xdp/Cargo.toml
@@ -8,6 +8,9 @@ license = { workspace = true }
 edition = { workspace = true }
 publish = true
 
+[features]
+agave-unstable-api = []
+
 [dependencies]
 crossbeam-channel = { workspace = true }
 libc = { workspace = true }
diff --git a/xdp/src/lib.rs b/xdp/src/lib.rs
index f3afcc128b816b..70f24eed07b942 100644
--- a/xdp/src/lib.rs
+++ b/xdp/src/lib.rs
@@ -1,3 +1,12 @@
+#![cfg_attr(
+    not(feature = "agave-unstable-api"),
+    deprecated(
+        since = "3.1.0",
+        note = "This crate has been marked for formal inclusion in the Agave Unstable API. From \
+                v4.0.0 onward, the `agave-unstable-api` crate feature must be specified to \
+                acknowledge use of an interface that may break without warning."
+    )
+)]
 // Activate some of the Rust 2024 lints to make the future migration easier.
 #![warn(if_let_rescope)]
 #![warn(keyword_idents_2024)]
diff --git a/zk-token-sdk/Cargo.toml b/zk-token-sdk/Cargo.toml
index 132704afc3f96c..593aaa38ec64ee 100644
--- a/zk-token-sdk/Cargo.toml
+++ b/zk-token-sdk/Cargo.toml
@@ -12,6 +12,9 @@ edition = { workspace = true }
 [lib]
 crate-type = ["cdylib", "rlib"]
 
+[features]
+agave-unstable-api = []
+
 [dependencies]
 base64 = { workspace = true }
 bytemuck = { workspace = true }
diff --git a/zk-token-sdk/src/lib.rs b/zk-token-sdk/src/lib.rs
index cd9467a0a143d4..67444c0dfa752f 100644
--- a/zk-token-sdk/src/lib.rs
+++ b/zk-token-sdk/src/lib.rs
@@ -1,3 +1,12 @@
+#![cfg_attr(
+    not(feature = "agave-unstable-api"),
+    deprecated(
+        since = "3.1.0",
+        note = "This crate has been marked for formal inclusion in the Agave Unstable API. From \
+                v4.0.0 onward, the `agave-unstable-api` crate feature must be specified to \
+                acknowledge use of an interface that may break without warning."
+    )
+)]
 // Deprecate the crate
 #![deprecated(
     since = "3.0.0",