Background & Motivation

TypeScript is the dominant choice for type-safe JavaScript development. Many azd users write their application code in TypeScript and want hooks in the same language. TypeScript requires a compilation step, making the executor more complex than JavaScript but following the same Node.js toolchain.

Parent Epic: #7435 — Multi-Language Hook Support
Phase 1 PR: #7451 — delivered the extensible framework and Python support
Depends on: #7621 (JavaScript Hook Executor) — shares Node.js patterns, package manager detection, node.Cli usage

User Story

As an azd user, I want to write hook scripts in TypeScript (.ts files) so that I can use type-safe JavaScript with the same zero-config experience as Python and JavaScript hooks.

Existing Infrastructure (from Phase 1)

The following already exist and are shared by all new executors:

• HookExecutor interface (pkg/tools/script.go) — Prepare/Execute/Cleanup lifecycle
• HookKind constant ts (pkg/tools/language/executor.go)
• InferKindFromPath() — maps .ts→ts
• Project discovery (pkg/tools/language/project_discovery.go) — walk-up for package.json
• IoC-based executor resolution in hooks_runner.go
• node.Cli singleton in cmd/container.go
• Schema support for kind: ts in azure.yaml.json
• ExecutionContext with Cwd, EnvVars, BoundaryDir, etc.

Solution Approach

• Create tsExecutor in pkg/tools/language/ts_executor.go implementing HookExecutor
• Two execution modes:
  • Standalone mode (no tsconfig.json): Use npx tsx script.ts for zero-config execution — no build step needed
  • Project mode (with tsconfig.json): npm install → npx tsc (or project build script) → node dist/script.js
• Prepare():
  • Validate Node.js is installed via node.Cli.CheckInstalled()
  • Discover tsconfig.json and package.json via DiscoverProjectFile()
  • If project mode: install deps (reuse JS executor's package manager detection), then build
  • If standalone: verify tsx is available (install as needed via npx)
• Execute():
  • Standalone: npx tsx script.ts
  • Project: node on compiled output (resolve from tsconfig outDir)
  • Pass environment variables, respect Cwd and Interactive
• Cleanup(): No-op
• Register "ts" as named transient in cmd/container.go
• Update docs/language-hooks.md with TypeScript section

Acceptance Criteria

• .ts hook scripts auto-detected and executed
• Standalone .ts scripts execute via npx tsx without requiring a build step or tsconfig.json
• Project .ts scripts with tsconfig.json are compiled then executed
• package.json dependencies installed before execution (when present)
• Missing Node.js → clear error with install URL
• kind: ts explicit override works in azure.yaml
• Environment variables passed through to script process
• Existing shell, Python, and JS hooks unaffected
• IoC registration as named transient "ts" in container.go

Out of Scope

• ESM/CJS module resolution complexities beyond what tsx handles
• Custom TypeScript compiler configurations (only standard tsc)
• Deno TypeScript execution

Testing Expectations

• Unit tests for tsExecutor (both standalone and project modes)
• Unit tests for tsconfig.json detection and outDir resolution
• E2E test: standalone .ts script → tsx execution → verify output
• E2E test: project .ts with tsconfig → build → execute → verify
• E2E test: missing Node.js → error with suggestion
• E2E test: continueOnError: true behavior

Constraints

• Must reuse node.Cli and share package manager detection with JS executor
• Standalone mode should not require any project scaffolding (zero-config)
• Follow the Prepare/Execute/Cleanup lifecycle pattern

Related Issues

• Parent Epic: Multi-Language Hook Support: Python, JavaScript, TypeScript, .NET #7435 — Multi-Language Hook Support
• Depends on: JavaScript Hook Executor #7621 (JavaScript Hook Executor) — shares Node.js patterns, package manager detection, node.Cli usage
• Resolved by Phase 1: PR feat: add multi-language hook support (Phase 1 — Python) #7451 — provides framework and project discovery