business-logic-guardian

Business Logic Guardian

Style: Mode-B-lite. Artifact-gated — inert unless a business-logic doc exists (docs/<app>/business-logic-index.md AI-default, or docs/<app>/business-logic.md human narrative).

Purpose

Protect documented business logic during fixes and improvements. The business-logic doc is a fast navigation/verify layer: confirm a change does not silently break documented behavior before committing. Complements FR-20 (zoom-out) and FR-10 (reproduce-before-fix).

Consumes whichever business-logic doc exists. Per FR-23 (flow-skills/documentation-budget/SKILL.md), the AI-default authoring format is the retrieval index templates/business-logic-index.md (tables + source paths); the narrative templates/business-logic.md is the explicit human-readable option. This skill reads either as the guard layer.

When to invoke

• docs/<app>/business-logic-index.md (AI-default retrieval index) or docs/<app>/business-logic.md (human narrative) exists AND a fix/improvement touches business behavior. If both exist, the index is the primary guard layer; the narrative is supplementary.
• Operator says "don't break the business logic", "does this change behavior".
• During Implement / post-gate fixes on an app that has documented logic.

Do not invoke when

• Neither docs/<app>/business-logic-index.md nor docs/<app>/business-logic.md exists → silent no-op; do not create either (use app-business-docs, or the FR-23 business-logic-index template, to author one deliberately).
• Net-new feature with no documented logic yet.
• Pure cosmetic edits.

Required inputs

Input	Where it lives	If missing
Business logic doc	docs/<app>/business-logic.md	STOP — no-op. Author via app-business-docs if wanted.
The change in progress	current diff/plan	nothing to check; exit

Procedure

1. Existence gate (FIRST STEP). No docs/<app>/business-logic.md → exit silently. Do not create it.
2. Read the documented business logic / main flows / edge cases.
3. Impact-check the change: does it alter, remove, or contradict any documented behavior or edge case?
4. Verify against code — the doc is the navigation layer; confirm the actual code path matches before trusting the doc (code is source of truth).
5. Flag any documented behavior the change would break; recommend preserving it or, if the change is intentional, updating the doc (via app-business-docs) in the same change.
6. Ambiguity → ask operator (FR-19).

Output artifacts

Artifact	Location	Mode
Business-logic impact check	chat / gate note	Mode A / Mode-B-lite

Failure cases

Failure	Detection	Response
Artifact absent	step 1	silent no-op (correct)
Change breaks documented behavior	step 3	flag; preserve or update-doc-in-same-change
Doc disagrees with code	step 4	trust code; note the doc is stale; suggest refresh

Escalation path

• Intentional behavior change → update docs/<app>/business-logic.md via app-business-docs.
• Conflict with a locked decision → ask operator (FR-11/FR-19).

Anti-patterns

• Do not activate/create the doc when absent.
• Do not trust the doc over the code (verify).
• Do not silently change documented behavior without flagging it.

Clean-room note

Original Fusebase Flow content. See docs/source-map.md. No third-party code, prompts, or skill files copied.