extract-service

name	extract-service
description	Extracts repeated operational mechanics (SDK, API, file-system, or network logic copy-pasted across handlers or actions) into a shared service layer — produces a stepwise migration plan, then applies it caller-by-caller with verification at each step. Use when the same "how" recurs across 2+ callers. Not for behavioral cleanup or dead code (use clean-code) or designing a system from scratch (use architect-system). For a quality review after migrating, see review-work.
argument-hint	[file or directory with the repeated logic]
allowed-tools	Read Edit Write Grep Glob Bash
metadata	{"version":"1.0.0","budget":"standard","estimated-cost":"$0.75-2"}

Extract Service — Service-Layer Extraction Orchestrator

Multi-agent. Lifts repeated operational mechanics (SDK / API / file-system / network logic copy-pasted across handlers) out of N callers into one shared service layer, then migrates caller-by-caller with verification — no observable behavior change.

Core Question: "Is this purely structural — same behavior, fewer copies of the same 'how'?"

Why, methodology, when NOT to extract: references/playbook.md [PLAYBOOK].

When To Use

• Same operational mechanics (SDK setup, API calls, file-system access, network/retry logic, auth boilerplate) copy-pasted across 2+ handlers, actions, or route files.
• Bug had to be fixed in N places, or was fixed in some-but-not-all.

When NOT: 1 caller (G6); orchestration/domain logic not mechanics (G7); behavioral cleanup → clean-code; new system design → architect-system; no tests AND behavior must be preserved → write tests first; red baseline → BLOCKED (G8). Exits: references/anti-patterns.md [ANTI-PATTERN].

Critical Gates — Read First

Critic verifies all 8 before any change. G1-5 = clean-code's 5 Golden Rules (preserve behavior · small incremental steps · check existing conventions · verify after each caller · rollback awareness). G6-8 extract-service-specific:

• G6 Extraction threshold — <2 real callers → NEEDS_CONTEXT.
• G7 Two-layer purity — service holds only the shared how; orchestration + domain rules stay in callers.
• G8 Baseline-green — red tests/build → BLOCKED.

Operator-approval gate (plan → apply): plan shown IN FULL; ask Apply this migration? [y/N]. No code edited until operator confirms. N/no response → plan-only DONE, stop. Not skipped under --fast. Full text + critic-FAIL recovery: references/procedures/critical-gates.md [PROCEDURE].

Before Starting

Per references/_shared/before-starting-check.md [PLAYBOOK]:

Artifact	Source	Use
.forsvn/index/manifest.json	(any)	Check prior run, staleness
docs/forsvn/experience/technical.md	(any)	Prior conventions
architecture/system-architecture.md	architect-system	Service-layer placement

Mode + Pre-Dispatch + Dispatch

budget: standard — auto-downgrades to Single-Agent Fallback for ≤3-caller scopes; --fast forces single-agent (safety gates still fire). Per references/_shared/mode-resolver.md. Session execution profile (single-vs-multi): inherit per references/_shared/execution-policy.md.

Pre-Dispatch (references/_shared/pre-dispatch-protocol.md [PROCEDURE]) — needed dimensions: target, caller count, mechanics that repeat, tech stack + test runner, conventions. Confirm ≥2 callers via grep (G6) before scan. Cold Start: ask which mechanics repeat + roughly how many callers. Write back to docs/forsvn/experience/technical.md.

Dispatch — 4 sub-agents (scanner → planner → migration → critic) across 3 layers + operator-approval gate. Roster + layers + protocol + routing + Single-Agent Fallback: references/procedures/dispatch-mechanics.md [PROCEDURE]. TS walkthrough: references/examples/extraction-walkthrough.md [EXAMPLE].

Artifact Contract

• Path: docs/forsvn/artifacts/product-extract-service-<YYYY-MM-DD>-<slug>.md (flat v2; re-run same slug same day → .v[N]).
• Lifecycle: snapshot.
• Frontmatter: skill, version, date, status (DONE/DONE_WITH_CONCERNS/BLOCKED/NEEDS_CONTEXT), stack (=product), review_surface (=none — decision_state: not_required), lifecycle, produced_by, provenance. Schema: references/_shared/artifact-contract-template.md.
• Two halves: Migration Plan (interface + caller order, pre-approval) + Applied Migration (per-caller results + critic verdict, post-apply). Plan-only ships just the first.
• Consumed by: review-work, clean-artifacts, operator. Template: references/report-template.md [PROCEDURE].

Anti-Patterns

Re-read before any change that smells off: references/anti-patterns.md [ANTI-PATTERN] — extracting at 1 caller; service with if (caller === 'x'); batch-migrating; domain rules sliding into the service.

Durable Rules (protected)

Completion Status

• DONE — plan approved, every caller migrated, behavior preserved (tests + build PASS), critic PASS. Also DONE when operator declined the approval gate and a plan-only artifact shipped.
• DONE_WITH_CONCERNS — applied but verification skipped (no test suite, uncovered callers, manual), or a subset migrated and rest flagged pending.
• BLOCKED — pre-existing test/build failure (G8); or critic FAIL with offending caller not cleanly revertible.
• NEEDS_CONTEXT — <2 callers (G6); or how/why-when split ambiguous.

Next Step

/review-work for a fresh-eyes review of migrated code. Re-run triggers: 3rd+ caller appears; interface needs a new param; prior run stopped with callers pending.

References

• references/{playbook, service-layer-pattern, migration-checklist, anti-patterns, report-template}.md
• references/procedures/{critical-gates, dispatch-mechanics}.md
• references/examples/extraction-walkthrough.md
• references/_shared/{pre-dispatch-protocol, before-starting-check, mode-resolver, manifest-spec, anti-sycophancy, artifact-contract-template}.md