typescript-compile-check-resilient

name	typescript-compile-check-resilient
description	TypeScript compile-checking in projects where npx and node_modules/.bin symlinks fail, with a filtering technique to isolate errors from only newly-created or task-specific files — ignoring pre-existing legacy errors.

TypeScript Compile-Check (Resilient) with File-Scoped Error Filtering

Use this workflow when you need to validate TypeScript changes in a project but the standard npx tsc or node_modules/.bin/tsc invocations fail due to broken symlinks, missing PATH entries, or environment issues.

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When to Use This Skill

• npx tsc fails with "command not found" or permission errors
• node_modules/.bin/tsc symlink is broken or unresolvable
• You need to validate only newly-created or task-specific files without being blocked by pre-existing compile errors in the broader codebase

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Step 1 — Invoke tsc Directly via node_modules

Bypass npx and symlinks entirely by calling the TypeScript binary directly:

node_modules/typescript/bin/tsc --noEmit 2>&1; echo EXIT:$?

Why this works: The tsc CLI entry point is a plain Node.js script at node_modules/typescript/bin/tsc. It does not depend on symlinks or PATH resolution. The --noEmit flag checks types without writing output files. Capturing EXIT:$? lets you programmatically detect success (EXIT:0) vs failure (EXIT:1 or higher).

If the project uses a custom tsconfig, specify it explicitly:

node_modules/typescript/bin/tsc --noEmit --project tsconfig.json 2>&1; echo EXIT:$?

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Step 2 — Filter Output to Task-Specific Files Only

When a legacy codebase has pre-existing errors, the full tsc output will be noisy and may cause false negatives. Pipe through grep to isolate errors from only the files you created or modified:

node_modules/typescript/bin/tsc --noEmit 2>&1 \
  | grep -E "(file-pattern)" ; echo EXIT:${PIPESTATUS[0]}

Examples

Single new file:

node_modules/typescript/bin/tsc --noEmit 2>&1 \
  | grep -E "settings-store\.ts"

Multiple new files (pipe-delimited pattern):

node_modules/typescript/bin/tsc --noEmit 2>&1 \
  | grep -E "(settings-keys|settings-store|preferences|SettingsModal)"

All files in a specific directory:

node_modules/typescript/bin/tsc --noEmit 2>&1 \
  | grep -E "src/features/my-feature/"

Check: no output = no errors in your files (success).

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Step 3 — Capture Exit Code Correctly Through a Pipe

When grepping, the shell exit code reflects grep, not tsc. Use ${PIPESTATUS[0]} (bash) to recover the original tsc exit code:

node_modules/typescript/bin/tsc --noEmit 2>&1 \
  | grep -E "(my-file-pattern)"; echo "TSC_EXIT:${PIPESTATUS[0]}"

Or store errors explicitly:

TSC_OUTPUT=$(node_modules/typescript/bin/tsc --noEmit 2>&1)
TSC_EXIT=$?
echo "$TSC_OUTPUT" | grep -E "(settings-keys|settings-store|preferences|SettingsModal)"
echo "TSC_EXIT:$TSC_EXIT"

The second approach (storing output in a variable) is the most reliable since $? is captured before the pipe.

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Step 4 — Interpret Results

Condition	Meaning
TSC_EXIT:0, no grep output	✅ Full project clean, your files are fine
TSC_EXIT:1, no grep output	✅ Your files are fine; pre-existing errors elsewhere (acceptable)
TSC_EXIT:1, grep output present	❌ Your files have errors — fix them
TSC_EXIT:2	❌ tsc configuration error (bad tsconfig, missing typescript package)

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Fallback: Verify TypeScript Is Installed

If node_modules/typescript/bin/tsc does not exist:

# Check if typescript is installed
ls node_modules/typescript/bin/tsc 2>/dev/null || echo "TypeScript not installed"

# Install if needed
npm install --save-dev typescript
# or
yarn add --dev typescript

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Full Example

# Store full tsc output and exit code
TSC_OUTPUT=$(node_modules/typescript/bin/tsc --noEmit 2>&1)
TSC_EXIT=$?

# Show only errors in newly-created files
NEW_FILE_ERRORS=$(echo "$TSC_OUTPUT" | grep -E "(settings-keys|settings-store|preferences|SettingsModal)")

if [ -z "$NEW_FILE_ERRORS" ]; then
  echo "✅ No TypeScript errors in new files (TSC_EXIT:$TSC_EXIT)"
else
  echo "❌ TypeScript errors in new files:"
  echo "$NEW_FILE_ERRORS"
  exit 1
fi

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Notes

• This technique is safe for CI and local environments alike.
• The direct node_modules/typescript/bin/tsc path works on macOS, Linux, and Windows (via node node_modules/typescript/bin/tsc on Windows CMD).
• On Windows, replace the bash script with: node node_modules/typescript/bin/tsc --noEmit
• Always prefer --noEmit for validation-only checks to avoid side effects.