refactor: migrate to TypeScript with Vitest and modern tooling (#311)

* refactor: migrate to TypeScript with Vitest and modern tooling

BREAKING CHANGE: @actions/github upgraded from v2 to v6

- Convert index.js to src/index.ts with strict TypeScript mode
- Extract pure utility functions to src/utils.ts for testability
- Add tsconfig.json with strict compiler options

- Replace Jest with Vitest for faster, ESM-native testing
- Add comprehensive unit tests for utility functions (43 tests)
- Add integration tests for GitHub Action structure (12 tests)
- Target: 80%+ code coverage

- Migrate from deprecated `new github.GitHub(token)` to `github.getOctokit(token)`
- Update all API calls from `octokit.repos.*` to `octokit.rest.repos.*`
- Update all API calls from `octokit.issues.*` to `octokit.rest.issues.*`
- Update all API calls from `octokit.git.*` to `octokit.rest.git.*`

- Enable TypeScript support in @antfu/eslint-config
- Replace Jest globals with Vitest globals (vi instead of jest)
- Add lib/ to ignore patterns

- Update ncc build to compile TypeScript directly
- Add source maps and licenses to dist output
- Add typecheck script for standalone type checking
- Update all npm scripts for TypeScript workflow

- index.js (migrated to src/index.ts)
- index.test.js (migrated to src/__tests__/*.test.ts)
- jest.config.js (replaced by vitest.config.ts)
- now.js (unused legacy file)

Closes #291

* chore: apply AI code review suggestions

- Move PullRequestPayload and ReleasePayload interfaces to top of file
- Use PullRequestPayload type instead of inline type assertion
- Simplify parseArgs regex match logic (remove redundant fallback)

* refactor: split index.ts into smaller modules

- Extract types to src/types.ts
- Extract config and initialization to src/config.ts
- Extract Vercel functions to src/vercel.ts
- Extract GitHub comment functions to src/github-comments.ts
- Refactor run() into smaller focused functions (< 50 LOC each)
- Add try-catch around execSync for git log with descriptive error
- Add error handling for GitHub API calls
- Make alias failures explicit with warning messages
- Extract magic numbers to named constants (RETRY_DELAY_MS, ALIAS_RETRY_COUNT)
- Use buildCommentPrefix() consistently in both comment functions

All files now under 300 LOC limit, all functions under 50 LOC limit.

* build: rebuild dist after refactoring

* build: update vercel to v50

* fix: improve error handling in vercel deploy and comment functions

- Extract and validate deployment URL from vercel CLI stdout
- Wrap vercelInspect exec in try-catch to prevent action failure
- Expand try-catch scope in comment functions to cover API lookups
- Route stderr to core.warning for better error visibility

* test: add tests for vercel, config, and github-comments modules

- Add vercel.test.ts: URL extraction, inspect regex, alias retry
- Add config.test.ts: alias domain substitution, env export
- Add github-comments.test.ts: comment create/update, error handling
- Total tests: 55 → 100

* fix: port personal account scope error handling from PR #297/#298

- Add core.setSecret for vercel token to prevent log exposure
- Disable telemetry with VERCEL_TELEMETRY_DISABLED env var
- Require both org and project IDs together (v41+ compat)
- Auto-retry deployment on personal account scope error
- Sanitize commit message newlines and quotes in metadata
- Add ignoreReturnCode for proper exit code handling
- Update tests for new behavior (105 total)

* refactor: use DeploymentContext object in vercelDeploy signature

Reduce parameter count from 6 to 2 by passing DeploymentContext
object instead of individual ref, commit, sha, commitOrg, commitRepo
arguments. Aligns with AGENTS.md parameter limit of 5.

* fix: port alias retry without --scope for personal accounts (#310)

Capture stderr in alias exec and retry without --scope when Vercel CLI
rejects personal account scope, matching the deploy retry pattern.
Add tests for alias scope retry, retry failure, and non-scope failures.

* fix: remove declaration maps to fix check-dist CI failure

Source map files (.d.ts.map) contain absolute local paths that differ
between local builds and CI runners, causing check-dist to fail.
Disable declarationMap in tsconfig.json since these files are not
needed for GitHub Action runtime execution.

* chore: apply AI code review suggestions

- Implement exponential backoff in retry function (was constant delay)
- Fix debug log for head_commit to use JSON.stringify
- Change vercelInspect stderr logging from warning to info level
- Fix retry after PERSONAL_ACCOUNT_SCOPE_ERROR to omit --scope
- Bump @types/node from ^20.0.0 to ^24.0.0 to match Node 24 runtime
- Add setSecret to @actions/core mock in index.test.ts
- Fix mock path in config.test.ts from ../package.json to ../../package.json
- Update test expectation to match mocked vercel version (30.0.0)
- Remove pull_request_target from PullRequestPayload (always undefined)
- Add per_page: 100 to comment listing API calls to reduce duplicate risk
- Fix Node version in session-summary.md (20 → 24)

* fix: make vercelScope optional to clean up retry cast in vercelDeploy

Co-authored-by: amondnet <1964421+amondnet@users.noreply.github.com>
Agent-Logs-Url: https://github.com/amondnet/vercel-action/sessions/16d171b4-3be8-43f8-a736-b5f3ff13deba

---------

Co-authored-by: copilot-swe-agent[bot] <198982749+Copilot@users.noreply.github.com>
Co-authored-by: amondnet <1964421+amondnet@users.noreply.github.com>

Author: amondnet

.please/memory/session-summary.md

@@ -0,0 +1,39 @@
+# Session Summary: TypeScript and Vitest Migration
+
+## Feature Description
+Migrate vercel-action from JavaScript to TypeScript with modern tooling:
+1. Convert index.js to TypeScript (src/index.ts)
+2. Replace Jest with Vitest for testing
+3. Update @antfu/eslint-config for TypeScript support
+
+## Requirements Summary
+- TypeScript source files in `src/` directory
+- Strict TypeScript mode enabled
+- Delete deprecated `now.js` file
+- Maintain backward compatibility with action inputs/outputs
+- Keep dist/index.js as bundled output
+
+## Constraints
+- GitHub Action must remain functional
+- Node 24 runtime requirement
+- ncc bundling for dist/
+
+## Current Phase: Codebase Exploration
+
+## Key Decisions
+- [x] Source directory: `src/`
+- [x] TypeScript strict mode: enabled
+- [x] Delete now.js: yes
+
+## Files to Modify
+- index.js → src/index.ts
+- index.test.js → src/index.test.ts
+- package.json (scripts, dependencies)
+- eslint.config.mjs (TypeScript support)
+- jest.config.js → vitest.config.ts
+- action.yml (verify dist path)
+- tsconfig.json (new)
+
+## Progress
+- [x] Phase 1: Discovery - Complete
+- [ ] Phase 2: Codebase Exploration - In Progress

.please/memory/tasklist.json

@@ -0,0 +1,43 @@
+{
+  "session_id": "20251212-typescript-vitest-migration",
+  "feature_name": "TypeScript and Vitest Migration",
+  "created_at": "2025-12-12T00:00:00Z",
+  "updated_at": "2025-12-12T00:00:00Z",
+  "status": "in_progress",
+  "current_phase": 6,
+  "issue_number": 291,
+  "branch": "291-refactor-migrate-to-typescript-with-vitest-and-modern-tooling",
+  "phases": [
+    { "number": 1, "name": "Discovery", "status": "completed", "started_at": "2025-12-12T00:00:00Z", "completed_at": "2025-12-12T00:01:00Z" },
+    { "number": 2, "name": "Codebase Exploration", "status": "completed", "started_at": "2025-12-12T00:01:00Z", "completed_at": "2025-12-12T00:02:00Z" },
+    { "number": 3, "name": "Clarifying Questions", "status": "completed", "completed_at": "2025-12-12T00:03:00Z" },
+    { "number": 4, "name": "Architecture Design", "status": "completed", "completed_at": "2025-12-12T00:04:00Z" },
+    { "number": 5, "name": "GitHub Issue & PR", "status": "completed", "completed_at": "2025-12-12T00:05:00Z" },
+    { "number": 6, "name": "Implementation", "status": "completed", "completed_at": "2025-12-12T00:22:00Z" },
+    { "number": 7, "name": "Quality Review", "status": "in_progress", "started_at": "2025-12-12T00:22:00Z" },
+    { "number": 8, "name": "PR Finalization", "status": "pending" }
+  ],
+  "tasks": [
+    { "id": "T001", "title": "Create tsconfig.json with strict settings", "phase": 6, "status": "pending", "parallel": true, "dependencies": [] },
+    { "id": "T002", "title": "Update package.json (add TypeScript, Vitest; remove Jest)", "phase": 6, "status": "pending", "parallel": true, "dependencies": [] },
+    { "id": "T003", "title": "Update eslint.config.mjs for TypeScript + Vitest globals", "phase": 6, "status": "pending", "parallel": true, "dependencies": [] },
+    { "id": "T004", "title": "Create vitest.config.ts", "phase": 6, "status": "pending", "parallel": true, "dependencies": [] },
+    { "id": "T005", "title": "Create src/utils.ts with pure utility functions", "phase": 6, "status": "pending", "parallel": false, "dependencies": ["T001", "T002", "T003", "T004"] },
+    { "id": "T006", "title": "Create src/__tests__/utils.test.ts with unit tests", "phase": 6, "status": "pending", "parallel": false, "dependencies": ["T005"] },
+    { "id": "T007", "title": "Create src/index.ts with main action logic", "phase": 6, "status": "pending", "parallel": false, "dependencies": ["T005"] },
+    { "id": "T008", "title": "Upgrade @actions/github to v6 and update API calls", "phase": 6, "status": "pending", "parallel": false, "dependencies": ["T007"] },
+    { "id": "T009", "title": "Create src/__tests__/index.test.ts", "phase": 6, "status": "pending", "parallel": false, "dependencies": ["T007", "T008"] },
+    { "id": "T010", "title": "Delete old files (index.js, index.test.js, jest.config.js, now.js)", "phase": 6, "status": "pending", "parallel": false, "dependencies": ["T007", "T009"] },
+    { "id": "T011", "title": "Build and verify dist/index.js", "phase": 6, "status": "pending", "parallel": false, "dependencies": ["T010"] },
+    { "id": "T012", "title": "Run all quality checks (lint, typecheck, test)", "phase": 6, "status": "pending", "parallel": false, "dependencies": ["T011"] }
+  ],
+  "decisions": {
+    "source_directory": "src/",
+    "keep_now_js": false,
+    "typescript_strict": true,
+    "modularize": false,
+    "add_comprehensive_tests": true,
+    "upgrade_github_api": true,
+    "split_utils": true
+  }
+}

dist/config.d.ts

@@ -0,0 +1,4 @@
+import type { ActionConfig, OctokitClient } from './types';
+export declare function getActionConfig(): ActionConfig;
+export declare function createOctokitClient(githubToken: string): OctokitClient | undefined;
+export declare function setVercelEnv(config: ActionConfig): void;

dist/github-comments.d.ts

@@ -0,0 +1,3 @@
+import type { ActionConfig, OctokitClient } from './types';
+export declare function createCommentOnCommit(octokit: OctokitClient, config: ActionConfig, deploymentCommit: string, deploymentUrl: string, deploymentName: string): Promise<void>;
+export declare function createCommentOnPullRequest(octokit: OctokitClient, config: ActionConfig, deploymentCommit: string, deploymentUrl: string, deploymentName: string): Promise<void>;

dist/index.d.ts

@@ -0,0 +1 @@
+export {};