Scan built-in pipelines: Use Glob("workflows/*.yaml") (NOT templates/) to find all pipeline definitions

Extract metadata: For each YAML file found, use Bash to extract name and description:

for f in workflows/*.yaml; do
  name=$(grep -m1 '^name:' "$f" | sed 's/^name: *//' | tr -d '"')
  desc=$(grep -m1 '^description:' "$f" | sed 's/^description: *//' | tr -d '"')
  echo "  $name — $desc"
done

Scan template pipelines: Use Glob("templates/workflows/*.yaml") for template examples

Display formatted output:

Available pipelines:
  {name} — {description}
  {name} — {description}

Template pipelines (in templates/workflows/):
  {name} — {description}

If no pipelines found, display: "No pipelines found in workflows/ directory."
If YAML parsing fails for a file, skip it and show: {filename} — (parse error, skipped)

Run Mode (with pipeline name)

Validate pipeline exists: workflows/{name}.yaml
Load and validate YAML structure:
- Required fields: name, description, steps[]
- Each step has either skill: or prompt: (not both)
- Referenced skills exist in .claude/skills/
- Skill names must match ^[a-z0-9-]+$ (kebab-case only) — reject path traversal attempts
Announce: [Pipeline] Starting {name} — {step_count} steps
Execute steps top-to-bottom:
- Skill steps (skill: name): Invoke via Skill tool — Skill(skill: "{name}")
- Prompt steps (prompt: text): Execute the described action using appropriate agents/tools
- Foreach steps (foreach: collection): Iterate over collection from previous step output
- Parallel steps (parallel: [step1, step2]): Execute contained steps concurrently using Agent tool. Each parallel step runs as an independent Agent. Max 4 concurrent per R009. Steps within a parallel block MUST be independent (no shared state, no sequential dependencies). Dependencies between parallel and non-parallel steps use depends_on: field.
- Agent mode: When spawning agents via Agent tool, always pass mode: "bypassPermissions" to match agent frontmatter. The Agent tool default (acceptEdits) overrides frontmatter permissionMode, causing permission prompts during unattended execution.
Report completion or failure

Resume Mode (/pipeline resume)

Scan /tmp/.claude-pipeline-*-{PPID}.json for state files
If none found: "No halted pipelines found."
If found: display pipeline name, failed step, error message
Options:
- Retry — Re-execute the failed step
- Skip — Mark failed step as skipped, continue to next
- Abort — Delete state file, cancel pipeline
On resume: execute from the failed step

State Tracking

Track per-step state:

{
  "pipeline": "{name}",
  "started": "ISO-8601",
  "status": "running|completed|halted",
  "current_step": 0,
  "steps": [
    {"name": "triage", "status": "completed", "duration_ms": 5000},
    {"name": "plan", "status": "running"}
  ]
}

State saved to /tmp/.claude-pipeline-{name}-{PPID}.json on failure.

Parallel Execution

Pipeline steps can be grouped for parallel execution:

steps:
  - name: phase-1
    parallel:
      - name: task-a
        skill: skill-a
        description: First independent task
      - name: task-b
        skill: skill-b
        description: Second independent task
  - name: phase-2
    skill: next-step
    depends_on: phase-1

Parallel Rules

Max 4 concurrent steps per parallel block (R009 hard cap)
Steps within a parallel block MUST be independent
depends_on enforces ordering between blocks
Each parallel step is spawned as a separate Agent tool call in the SAME message
If any parallel step fails with error: halt-and-report, all remaining steps in the block are cancelled
State tracking records each parallel step individually

Parallel State Format

{
  "name": "phase-1",
  "type": "parallel",
  "status": "running",
  "children": [
    {"name": "task-a", "status": "completed", "duration_ms": 5000},
    {"name": "task-b", "status": "running"}
  ]
}

Error Handling

Pipeline not found → list available pipelines with suggestion
YAML parse error → report with line number
Step failure (error: halt-and-report) → stop execution, save state, report failure with context
All file writes delegated to subagents per R010

pipeline

/pipeline — Pipeline Invocation

Usage

Behavior

List Mode (no arguments or --list flag)