---

name: speckit-08-implement description: Execute implementation plan by processing all tasks in tasks.md

Spec-Kit Implement

Execute the implementation plan by processing and executing all tasks defined in tasks.md.

User Input

$ARGUMENTS

You MUST consider the user input before proceeding (if not empty).

Constitution Loading (REQUIRED)

Before ANY action, load and internalize the project constitution:

1. Read constitution:

   cat .specify/memory/constitution.md 2>/dev/null || echo "NO_CONSTITUTION"
   

2. If file doesn't exist:

   ERROR: Project constitution not found at .specify/memory/constitution.md
   
   Cannot proceed without constitution.
   Run: /speckit-00-constitution
   

3. Parse all principles, constraints, and governance rules.

4. Extract Enforcement Rules: Find all MUST, MUST NOT, SHALL, REQUIRED, NON-NEGOTIABLE statements. These rules are checked BEFORE EVERY FILE WRITE.

5. Hard Gate Declaration:

   CONSTITUTION ENFORCEMENT GATE ACTIVE
   Extracted: X enforcement rules
   Mode: STRICT - violations HALT implementation
   

Prerequisites Check

1. Run prerequisites check:

   .claude/skills/speckit-core/scripts/bash/check-prerequisites.sh --json --require-tasks --include-tasks
   

2. Parse JSON for FEATURE_DIR and AVAILABLE_DOCS.

3. If error or missing tasks.md:

   ERROR: tasks.md not found in feature directory.
   Run: /speckit-06-tasks
   

Pre-Implementation Validation

BEFORE any implementation, perform complete validation sweep:

Artifact Completeness Check

Artifact	Required	Check
constitution.md	YES	Has principles section
spec.md	YES	Has Requirements + Success Criteria
plan.md	YES	Has Technical Context defined
tasks.md	YES	Has at least one task
checklists/*.md	YES	At least one checklist

Cross-Artifact Consistency

1. Spec → Tasks: Every FR-XXX should have corresponding task(s)
2. Plan → Tasks: Tech stack should match task file paths
3. Constitution → Plan: Verify no constitution violations

Readiness Score

Report: Artifacts complete, Spec coverage %, Plan alignment, Constitution compliance, Checklist status, Dependencies valid. Output READY or BLOCKED.

Checklist Gating (CRITICAL)

1. Read each checklist file in FEATURE_DIR/checklists/
2. Count: Incomplete (- [ ]) vs Complete (- [x])
3. PASS: All checklists 100% → proceed
4. FAIL: Ask user to proceed or halt

Execution Flow

1. Load Implementation Context

• REQUIRED: tasks.md, plan.md
• IF EXISTS: data-model.md, contracts/, research.md, quickstart.md, tests/test-specs.md

2. TDD Support Check

If tests/test-specs.md exists, perform assertion integrity verification:

Step 1: Run comprehensive integrity check

.claude/skills/speckit-core/scripts/bash/testify-tdd.sh comprehensive-check \
    "FEATURE_DIR/tests/test-specs.md" \
    ".specify/context.json" \
    ".specify/memory/constitution.md"

Step 2: Parse the JSON response

{
    "overall_status": "PASS|BLOCKED|WARN",
    "block_reason": "...",
    "tdd_determination": "mandatory|optional|forbidden",
    "checks": {
        "context_hash": "valid|invalid|missing",
        "git_note": "valid|invalid|missing",
        "git_diff": "clean|modified|untracked"
    }
}

Step 3: Act on results

overall_status	Action
PASS	Proceed with implementation
BLOCKED	HALT - Display block_reason, require remediation
WARN	Display warning, proceed with caution

BLOCKED remediation:

ASSERTION INTEGRITY CHECK FAILED

Status: BLOCKED
Reason: [block_reason from JSON]

The test assertions have been modified since testify ran.
This violates TDD principles - tests define expected behavior BEFORE implementation.

Remediation options:
1. Revert assertion changes: git checkout -- FEATURE_DIR/tests/test-specs.md
2. Re-run testify to regenerate test-specs: /speckit-05-testify
3. If legitimate spec changes occurred, update spec.md first, then re-run testify

Cannot proceed until assertion integrity is restored.

Display circular verification warning:

⚠️  TDD INTEGRITY ACTIVE

Test assertions are locked. During implementation:
- Fix CODE to pass tests, never modify assertions
- If a test seems wrong, re-run /speckit-05-testify from updated spec
- Assertion tampering will block future implementation runs

If TDD is mandatory in constitution but test-specs.md missing → ERROR:

ERROR: TDD is MANDATORY per constitution but tests/test-specs.md not found.

Run: /speckit-05-testify

Cannot proceed without test specifications.

2.1 Test Execution Enforcement (CRITICAL)

Tests MUST be run, not just written. Writing tests without executing them defeats TDD.

Mandatory rules:

1. After writing any test file: Run the test immediately to verify it fails (red phase)
2. After implementing code: Run tests again to verify they pass (green phase)
3. Before marking ANY test-related task complete: Tests MUST have been executed with visible output
4. "Run test suite" tasks: Execute ALL tests (unit, integration, e2e) and verify pass/fail status

What counts as "tests run":

• Actual execution output showing test results (PASS/FAIL counts)
• NOT just "tests written" or "test file created"
• NOT assuming tests pass without running them

Blocking conditions:

• Cannot mark implementation complete if tests haven't been run
• Cannot mark "run tests" task as [x] without actual execution output
• If any tests fail, fix code (not tests) before proceeding

Test execution commands by stack:

Stack	Command
Node/TypeScript	npm test or npx vitest or npx jest
Python	pytest or python -m pytest
Go	go test ./...
Rust	cargo test
E2E (Playwright)	npx playwright test
E2E (Cypress)	npx cypress run

Deterministic verification (REQUIRED):

After running tests, verify execution with:

Unix/macOS/Linux:

.claude/skills/speckit-core/scripts/bash/verify-test-execution.sh verify \
    "FEATURE_DIR/tests/test-specs.md" \
    "$(cat test-output.log)"

Windows (PowerShell):

pwsh .claude/skills/speckit-core/scripts/powershell/verify-test-execution.ps1 verify `
    "FEATURE_DIR/tests/test-specs.md" `
    (Get-Content test-output.log -Raw)

The script returns JSON with status:

• PASS - All tests ran and passed
• TESTS_FAILING - Tests ran but some failed → fix code
• INCOMPLETE - Fewer tests ran than expected in test-specs.md
• NO_TESTS_RUN - Could not detect test execution → tests weren't run

Block on any status other than PASS.

3. Tessl Integration

If Tessl installed, use tiles for library documentation. See tessl-integration.md for detailed patterns.

Key rule: Before implementing code using a tile's library, query mcp__tessl__query_library_docs.

4. Project Setup

Scaffolding in existing directories: When using project scaffolding tools (e.g., create-next-app, create-vite, cargo init, go mod init) in a directory with existing spec-kit artifacts, use force/overwrite flags to prevent conflicts:

• npx create-next-app . --force
• npm create vite . -- --force
• cargo init --name project (works in non-empty dirs)

The spec-kit files (.specify/, .claude/, AGENTS.md, etc.) won't be overwritten by these tools.

Create/verify ignore files based on tech stack. See ignore-patterns.md for patterns by technology.

5. Parse and Execute Tasks

Extract from tasks.md:

• Task phases, dependencies, parallel markers [P]
• Execute phase-by-phase, respecting dependencies
• Parallel tasks [P] can run together

Execution rules:

• Query Tessl tiles before implementing library code
• Tests before code if TDD
• Run tests after writing them - verify red/green cycle
• Never mark test tasks complete without execution output
• Mark completed tasks as [x] only after verification

6. Output Validation (REQUIRED)

Before writing ANY file:

1. Review against EACH constitutional principle
2. If violation: STOP, explain, suggest alternative
3. If compliant: proceed

7. Progress Tracking

• Report after each task
• Halt on non-parallel task failure
• Mark completed tasks [x] in tasks.md

8. Completion

Pre-completion checklist:

• All tasks marked [x] in tasks.md
• Features validated against spec requirements
• ALL tests executed (not just written) with passing results
• Test output shown/logged as evidence
• Report Tessl tile usage if applicable

CANNOT declare completion if:

• Tests exist but were never run
• Test execution shows failures
• "Run test suite" task marked complete without actual execution

Error Handling

Condition	Response
Tasks file missing	STOP: Run /speckit-06-tasks
Plan file missing	STOP: Run /speckit-03-plan
Constitution violation	STOP, explain, suggest alternative
Checklist incomplete	Ask user, STOP if declined
Task fails	Report error, halt sequential
Tests written but not run	STOP: Execute tests before marking complete
Tests failing	STOP: Fix code (not tests), re-run until green

Next Steps

Implementation complete! Next steps:
- Run tests to verify functionality
- Commit and push changes
- /speckit-09-taskstoissues - (Optional) Export tasks to GitHub Issues