Spec evolution

Spec Evolution

Purpose

spec-evolution keeps specs alive as the source of truth. When implementation reality teaches that an approved spec is incomplete, wrong, obsolete, or conflicting, this workflow resolves the mismatch deliberately before more code is written.

This is not a shortcut around spec-driven-development. It is the controlled path for changing a spec after evidence shows the current spec no longer matches the project.

Core Rule

Do not silently change code to fit reality or silently change the spec to fit code.
Resolve the mismatch explicitly, then continue.

If the mismatch affects behavior, architecture, data, security, release policy, or user-visible workflow, user approval is required before implementation continues.

When To Use

Use this workflow when:

• Tests or implementation reveal the approved spec is impossible or unsafe.
• Code review finds behavior that is useful but not specified.
• Existing code contradicts a new spec.
• A user asks to change requirements after a spec or plan was approved.
• A dependency, API, data model, or platform constraint invalidates the spec.
• A bug fix discovers the desired behavior differs from documented behavior.

Do not use it for:

• Initial spec creation. Use spec-driven-development.
• Pure typo fixes in a spec with no behavior meaning.
• Implementation bugs where the spec is clear and correct. Use test-driven-development or diagnose.

Workflow

1. Freeze Execution

Stop implementation, planning, review approval, or release progression until the mismatch is classified.

State:

Spec evolution gate: execution paused because <spec> and <evidence> disagree.

2. Gather Evidence

Read the minimum required context:

• The approved spec or source-of-truth section
• The code, test, review finding, user request, or runtime evidence that contradicts it
• Any ADR, PRD, API contract, or README section that constrains the decision
• For existing-domain evolution, SHOULD query recent related ledger entries via /trace-history to avoid repeating or reversing prior decisions without evidence

Do not infer drift from memory. Cite the concrete file, section, test, command, or review finding.

3. Classify the Mismatch

Use one primary classification:

Type	Meaning	Default action
Spec Gap	Required behavior was never specified	Amend spec before planning/code
Spec Error	Spec requirement is wrong, unsafe, or impossible	Propose correction and rationale
Code Drift	Code differs from correct spec	Keep spec, fix code with TDD
Reality Change	External constraint changed after approval	Update spec and plan
Scope Change	User wants a new behavior	Treat as new spec delta
Architecture Drift	Implementation violates architecture or ADR	Escalate to ADR or technical-director

If more than one type applies, list secondary types but choose the one that controls the next action.

4. Propose Evolution Options

Present options, not a hidden decision:

• Option A: Keep spec, change code when the spec is still correct.
• Option B: Amend spec, then re-plan/re-test when the spec is incomplete or wrong.
• Option C: Split into follow-up spec when the new behavior is valuable but outside current scope.
• Option D: Escalate to ADR when the change affects durable architecture, data model, security, deployment, or cross-team contracts.

For each option, include impact on:

• Files/spec sections
• Tests and verification
• Existing implementation or plan
• Risk and rollback

5. Request Approval For Material Evolution

Ask for explicit approval before changing any spec or continuing implementation when the evolution changes behavior, architecture, data, security, release policy, or acceptance criteria.

Approval must name the selected option. If approval is absent, stop.

6. Handoff After Decision

After approval:

• If the spec changes, update the spec through the appropriate edit workflow and route to review-spec.
• If code must change to match the current spec, route to test-driven-development with a regression or compliance test.
• If the plan must change, route to planning-and-task-breakdown.
• If architecture changes, route to architecture-decision-records before code.
• Before claiming resolution, use verification-before-completion.

Output Format

## Spec Evolution: [Topic]

**Spec Source:** [path/section]
**Evidence Source:** [code/test/review/user request/runtime evidence]
**Mismatch Type:** Spec Gap | Spec Error | Code Drift | Reality Change | Scope Change | Architecture Drift

### Mismatch
[One precise paragraph explaining the disagreement.]

### Options
1. **Keep spec, change code:** [impact, verification, risk]
2. **Amend spec, re-plan/re-test:** [impact, verification, risk]
3. **Split follow-up:** [impact, verification, risk]
4. **Escalate to ADR:** [when applicable, or "Not needed"]

### Recommendation
[Selected option and why.]

### Approval Needed
[Exact approval sentence needed before edits/implementation continue.]

Anti-Rationalizations

Thought	Required correction
"I'll just update the code; the spec was probably stale."	Prove and classify the mismatch first.
"I'll update the spec after the fix."	Spec changes before implementation continuation, not after.
"This is just a small requirement change."	Small behavior changes still alter acceptance criteria.
"Review can approve this as an improvement."	Unspecified improvements are scope changes.
"The implementation is better than the spec."	Maybe. Present options and get approval.

Integration

• review-spec routes here when it finds spec/code drift.
• code-review should route here when code implements behavior outside the approved spec.
• test-driven-development should route here when a RED test exposes an incorrect or incomplete spec.
• planning-and-task-breakdown should route here when a plan cannot be derived from the current spec without inventing requirements.
• architecture-decision-records is required when evolution changes durable architecture or cross-system contracts.