workflow-extend

name	workflow-extend
description	Captures a mid-PR sub-idea and implements it on the same branch as the existing PR — skips Phase 1 (Branch), preserves Verify → Review → Deliver, and uses workflow-commit-and-pr to update existing PR. Never creates a new branch or new PR.
orchestrator	true

Announce at start: "Using swe-workbench:workflow-extend — capturing and implementing sub-idea onto the existing PR."

When to invoke

• /swe-workbench:extend command
• "extend the PR", "add this on top of the current PR"
• Mid-PR follow-on idea surfaces while working on an in-flight branch
• Related sub-idea that belongs on the same branch and same PR

When NOT to invoke

• No open PR exists for the current branch → command body owns the fallback (AskUserQuestion)
• Sub-idea is unrelated to current PR → use /swe-workbench:implement for a fresh branch
• PR is already merged → use /swe-workbench:implement for a follow-up PR
• Bug on someone else's PR → use /swe-workbench:debug

Precondition

The command body detects the open PR before activating this skill and passes:

• PR_NUM — open PR number
• HEAD_REF — current branch name
• PR_URL — URL of the existing open PR
• IS_DRAFT — "true" if the PR is a draft, "false" otherwise (always lowercase)

If PR_NUM, HEAD_REF, or PR_URL are absent, fail loudly: "workflow-extend requires an open PR on the current branch. Run gh pr view to diagnose or use the command-level fallback." If IS_DRAFT is absent, treat as non-draft and log a warning.

Phase A — Capture (inline; no top-level issue by default)

Apply the four lenses with brevity. Use agents/product-manager.md lens phrasing as canonical reference — do NOT invoke the product-manager agent (its filing-centric contract is wrong here).

1. Problem. User pain or constraint, stated as the user's pain — not the feature.
2. Value. Who benefits and how. One "so-what" sentence.
3. Acceptance criteria. 2–4 bullets (Given/When/Then or simple bullets).
4. Impact / Effort. Impact: S/M/L and Effort: S/M/L, one sentence each.

Obtain a Unix timestamp: TS=$(date +%s). Write spec to /tmp/extend-${TS}.md using the Write tool. Print the spec to the user. Require explicit confirmation before proceeding.

Opt-in escalations (only when user phrase matches)

User phrase	Action
"consult senior-engineer" / "this is architectural"	Invoke senior-engineer subagent for a boundary read; fold its AC output into the spec before confirming.
"frame as a bug" / "this is a regression"	Route entirely to swe-workbench:debugger subagent; skip Phases B–D (debugger has its own verify+review loop). Commit per debugger output on the existing branch.
"also file an issue" / "track this in github"	After Phase D delivery, chain product-manager agent (its confirm gate handles filing).

Phase B — Plan (extend section)

Render skills/workflow-extend/templates/plan-extend-section.md into the spec. Substitute markers:

• [[detect:branch-name]] → HEAD_REF from context
• [[detect:pr-url]] → PR_URL from context
• [[detect:pr-number]] → PR_NUM from context
• [[detect:commit-style]] → from git log --oneline -5 (detect [type] vs type: pattern)
• [[detect:test-command]], [[detect:format-command]], [[detect:lint-command]] → from Makefile grep or package.json scripts

Do NOT invoke workflow-development Mode A here — this skill renders its own template. Phase 1 (Branch) is intentionally absent.

Phase C — Implement, Verify, Review

Hand off to swe-workbench:workflow-development Mode B starting at Phase 2 (Implement), citing skip-phase-1: existing branch [[detect:branch-name]] reused from open PR [[detect:pr-number]] so the orchestrator does not attempt worktree creation.

Phase 2: Execute implementation tasks using superpowers:executing-plans or superpowers:subagent-driven-development. Apply swe-workbench:principle-tdd per unit: red → green → refactor.

Phase 3 (Verify): Run superpowers:verification-before-completion. Do not advance until all format / lint / test steps pass with evidence.

Phase 4 (Review): Dispatch BOTH reviewers IN PARALLEL — in a single batch (same turn), as two distinct required invocations, neither optional:

• superpowers:requesting-code-review (a Skill) — plan-alignment and standards
• swe-workbench:reviewer (a subagent) — diff correctness/security/design in Severity | File:Line | Issue | Why it matters | Suggested fix format

Running the Skill inline and skipping the swe-workbench:reviewer subagent (or vice-versa) does not satisfy this phase.

The swe-workbench:reviewer subagent must additionally check: does the diff scope match the captured AC? Flag scope creep as Severity: High | scope-creep | <files> and ask user to confirm or carve out before proceeding.

Do not advance to Phase D until Phase C review passes clean or all issues are resolved.

Phase D — Deliver via workflow-commit-and-pr

Commit format: [<type>] sub-idea: <one-line restatement> (e.g. [feat] sub-idea: retry on transient client errors).

Commit body must include Ref: extend-${TS} on its own line.

Push. Then invoke swe-workbench:workflow-commit-and-pr. That skill will surface an "Update existing PR" AskUserQuestion — the user must select it. Never call gh pr create when an open PR exists for this branch. Tell the user to expect this prompt and select "Update existing PR".

Optional: if the user opts in ("append follow-on section"), fetch the current PR body first (gh pr view --json body -q .body), append the ## Follow-on section, write to a tempfile, then gh pr edit --body-file <tmp> — this avoids overwriting collaborator edits.

Before any script call in Phase B (when $TS is first written), bind the plugin root:

_RT="${CLAUDE_PLUGIN_ROOT:-$(git rev-parse --show-toplevel)}"
[ -f "$_RT/runtime/clean-state-files.sh" ] || {
  echo "swe-workbench runtime scripts not found under $_RT/runtime — set CLAUDE_PLUGIN_ROOT and retry." >&2
  exit 1
}

After Phase D delivery succeeds, delete the spec temp file. The reap runs foreground without suppression:

bash "$_RT/runtime/clean-state-files.sh" "/tmp/extend-${TS}.md"
[ -e "/tmp/extend-${TS}.md" ] && echo "⚠ state file NOT reaped: /tmp/extend-${TS}.md" >&2 || echo "✓ state file reaped: /tmp/extend-${TS}.md"

The Ref: extend-${TS} commit traceability string remains in git history; only the temp file is removed. On abort before delivery, leave the file for inspection.

Project Detection

Inherits detections from workflow-development for shared markers; adds extend-specific PR markers.

Detection markers used by templates/plan-extend-section.md:

• branch-name — git rev-parse --abbrev-ref HEAD
• pr-url — gh pr view --json url -q '.url'
• pr-number — gh pr view --json number -q '.number'
• extend-ts — TS captured in Phase A via date +%s; substitute manually into template (no shell script context)
• commit-style — from git log --oneline -5 (detect [type] vs type: pattern)
• format-command — from Makefile format target or language-marker fallback
• lint-command — from Makefile lint target or language-marker fallback
• test-command — from Makefile test target or language-marker fallback

Failure modes

Failure	Signal	Action
PR detection fails at skill entry	PR_NUM/HEAD_REF/PR_URL absent from context	Fail loudly with diagnostic hint.
PR merged mid-flow	gh pr view returns MERGED at Phase D	Abort. Print PR URL. Suggest /swe-workbench:implement for a follow-up PR.
Push rejected (non-FF)	git push non-zero	Abort. Tell user: git pull --rebase. Never force-push.
Scope creep flagged in review	Reviewer flags `Severity: High	scope-creep`
Dirty working tree at invocation	git status --porcelain non-empty	Abort. Prompt user to commit or stash uncommitted changes.
HEAD_REF is main or master	Branch check	Fail loudly: "Cannot extend from a trunk branch. Checkout a feature branch first."
Draft PR	gh pr view returns isDraft: true	Treat as OPEN. Note in output. Do not auto-mark ready-for-review.

Common mistakes

Mistake	Fix
Auto-creating a new PR	Never call gh pr create when an open PR exists. Use Update existing PR path.
Skipping Verify because "small change"	Always run Phase 3. Small changes have bugs too.
Forgetting Ref: extend-<ts> in commit body	The commit body traceability line is required — include it every time.
Invoking senior-engineer heuristically	Only on explicit user opt-in. Never auto-route to escalation agents.
Calling workflow-development Phase 1	Phase 1 is intentionally skipped. Cite skip-phase-1 rationale explicitly.