Update copilot instructions and setup steps with new stuff (#1350)

Co-authored-by: copilot-swe-agent[bot] <198982749+Copilot@users.noreply.github.com>
Co-authored-by: jakebailey <5341706+jakebailey@users.noreply.github.com>

Author: Copilot

.github/copilot-instructions.md

@@ -9,23 +9,29 @@ Most of our development takes place in the `internal` directory, and most behavi
 
 Most development on the codebase is in Go.
 Standard Go commands and practices apply, but we primarily use a tool called `hereby` to build, run tests, and other tasks.
-Feel free to install `hereby` globally (`npm install -g hereby`) if it is easier, and run `hereby --list` to see all available commands.
+Run `npx hereby --list` to see all available commands.
 
 ```sh
-hereby build  # Build the project
-hereby test   # Run tests
-hereby format # Format the code
-hereby lint   # Run linters
+npx hereby build  # Build the project
+npx hereby test   # Run tests
+npx hereby format # Format the code
+npx hereby lint   # Run linters
+
+# To run a specific compiler test:
+go test -run='TestSubmodule/<test name>' ./internal/testrunner  # For submodule tests in _submodules/TypeScript
+go test -run='TestLocal/<test name>' ./internal/testrunner     # For local tests in testdata/tests/cases
 ```
 
-Always make sure code is formatted, linted, and tested before sending a pull request.
-
+Always make sure code is formatted, linted, and tested before sending a pull request.
+
 ## Compiler Features, Fixes, and Tests
 
 When fixing a bug or implementing a new feature, at least one minimal test case should always be added in advance to verify the fix.
 This project primarily uses snapshot/baseline/golden tests rather than unit tests.
 New compiler tests are written in `.ts`/`.tsx` files in the directory `testdata/tests/cases/compiler/`, and are written in the following format:
 
+**Note:** Issues with editor features cannot be tested with compiler tests in `testdata/tests/cases/`. Editor functionality requires integration testing with the language server.
+
 ```ts
 // @target: esnext
 // @module: preserve
@@ -79,6 +85,12 @@ It is ideal to implement features and fixes in the following order, and commit c
 
 It is fine to implement more and more of a feature across commits, but be sure to update baselines every time so that reviewers can measure progress.
 
+## Code Porting Reference
+
+The code in `internal` is ported from the code in `_submodules/TypeScript`.
+When implementing features or fixing bugs, those files should be searched for similar functions when code is either missing or potentially wrong.
+The TypeScript submodule serves as the reference implementation for behavior and functionality.
+
 # Other Instructions
 
 - Do not add or change existing dependencies unless asked to.

.github/workflows/copilot-setup-steps.yml

@@ -23,8 +23,13 @@ jobs:
       - uses: dtolnay/rust-toolchain@fcf085fcb4b4b8f63f96906cd713eb52181b5ea4 # stable
       - uses: ./.github/actions/setup-go
         with:
+          # Updated to 1.25.0-rc.1 to improve compilation time
+          go-version: '>=1.25.0-rc.1'
           cache-name: copilot-setup-steps
       - run: npm i -g @playwright/mcp@0.0.28
       - run: npm ci
       # pull dprint caches before network access is blocked
       - run: npx hereby check:format || true
+      # cache build and lint operations
+      - run: npx hereby build || true
+      - run: npx hereby lint || true