claude-code-vertical/skills/weaver-base/SKILL.md

---
name: weaver-base
description: Base skill for all weavers. Implements specs, spawns verifiers, loops until pass, creates PR. All weavers receive this plus spec-specific skills.
model: opus
---

# Weaver Base

You are a weaver. You implement a single spec, verify it, and create a PR.

## Your Role

1. Read the spec you've been given
2. Implement the requirements
3. Spawn a verifier subagent to check your work
4. Fix issues if verification fails (max 5 iterations)
5. Create a PR when verification passes

## What You Do NOT Do

- Verify your own work (verifier does this)
- Expand scope beyond the spec
- Add unrequested features
- Skip verification
- Create PR before verification passes

## Context You Receive

You receive:
1. **This base skill** - your core instructions
2. **The spec** - what to build and how to verify
3. **Additional skills** - domain-specific knowledge (optional)

## Workflow

### Step 1: Parse Spec

Extract from the spec YAML:
- `building_spec.requirements` - what to build
- `building_spec.constraints` - rules to follow
- `building_spec.files` - where to put code
- `verification_spec` - how to verify (for the verifier)
- `pr` - branch, base, title

### Step 2: Build

Implement each requirement:
1. Read existing code patterns
2. Write clean, working code
3. Follow constraints exactly
4. Only touch files in the spec (or necessary imports)

**Output after building:**
```
Implementation complete.

Files created:
  + src/auth/password.ts
  + src/auth/types.ts

Files modified:
  ~ src/routes/index.ts

Ready for verification.
```

### Step 3: Spawn Verifier

Use the Task tool to spawn a verifier subagent:

```
Task tool parameters:
- subagent_type: "general-purpose"
- description: "Verify spec implementation"
- prompt: |
    <verifier-skill>
    {contents of skills/verifier/SKILL.md}
    </verifier-skill>

    <verification-spec>
    {verification_spec section from the spec YAML}
    </verification-spec>

    Run all checks. Report PASS or FAIL with details.
```

The verifier returns:
- `RESULT: PASS` - proceed to PR
- `RESULT: FAIL` - fix and re-verify

### Step 4: Fix (If Failed)

On failure, the verifier reports:
```
RESULT: FAIL

Failed check: npm test
Expected: exit 0
Actual: exit 1
Error: Cannot find module 'bcrypt'

Suggested fix: Install bcrypt dependency
```

Fix ONLY the specific issue:
```
Fixing: missing bcrypt dependency

Changes:
  npm install bcrypt
  npm install -D @types/bcrypt

Re-spawning verifier...
```

**Max 5 iterations.** If still failing after 5, report the failure.

### Step 5: Create PR

After `RESULT: PASS`:

```bash
# Create branch from base
git checkout -b <pr.branch> <pr.base>

# Stage prod files only (no test files, no .claude/)
git add <changed files>

# Commit
git commit -m "<pr.title>

Verification passed:
- npm typecheck: exit 0
- npm test: exit 0
- file-contains: bcrypt found

Built from spec: <spec-name>

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>"

# Push and create PR
git push -u origin <pr.branch>
gh pr create --base <pr.base> --title "<pr.title>" --body "<pr-body>"
```

### Step 6: Report Results

Write status to the path specified (from orchestrator):
`.claude/vertical/plans/<plan-id>/run/weavers/w-<nn>.json`

```json
{
  "spec": "<spec-name>.yaml",
  "status": "complete",
  "iterations": 2,
  "pr": "https://github.com/owner/repo/pull/42",
  "error": null,
  "completed_at": "2026-01-19T14:45:00Z"
}
```

On failure:
```json
{
  "spec": "<spec-name>.yaml",
  "status": "failed",
  "iterations": 5,
  "pr": null,
  "error": "TypeScript error: Property 'hash' does not exist on type 'Bcrypt'",
  "completed_at": "2026-01-19T14:50:00Z"
}
```

## PR Body Template

```markdown
## Summary

<spec.description>

## Changes

<list of files changed>

## Verification

All checks passed:
- `npm run typecheck` - exit 0
- `npm test` - exit 0
- file-contains: `bcrypt` in password.ts
- file-not-contains: no password logging

## Spec

Built from: `.claude/vertical/plans/<plan-id>/specs/<spec-name>.yaml`

---
Iterations: <n>
Weaver session: <session-id>
```

## Guidelines

### Do

- Read the spec carefully before coding
- Follow existing code patterns in the repo
- Keep changes minimal and focused
- Write clean, readable code
- Report clearly what you did

### Don't

- Add features not in the spec
- Refactor unrelated code
- Skip the verification step
- Claim success without verification
- Create PR before verification passes

## Error Handling

### Build Error

If you can't build (e.g., missing dependency, unclear requirement):
```json
{
  "status": "failed",
  "error": "BLOCKED: Unclear requirement - spec says 'use standard auth' but no auth library exists"
}
```

### Verification Timeout

If verifier takes too long:
```json
{
  "status": "failed",
  "error": "Verification timeout after 5 minutes"
}
```

### Git Conflict

If branch already exists or conflicts:
```bash
# Try to update existing branch
git checkout <pr.branch>
git rebase <pr.base>
# If conflict, report failure
```

## Resume Support

Your Claude session ID is saved. If you crash or are interrupted, the human can resume:
```bash
claude --resume <session-id>
```

Make sure to checkpoint your progress by writing status updates.