4 added, 4 removed. Audit A to A.
---
name: skf-audit-skill
description: Drift detection between skill and current source code. Use when the user requests to "audit a skill" or "audit skill" for drift.
---
# Audit Skill
## Overview
Detects drift between an existing skill and its current source code, producing a severity-graded drift report with AST-backed findings and actionable remediation suggestions. Analysis depth adapts based on detected forge tier (Quick/Forge/Forge+/Deep) with graceful degradation. Stack skills are supported: code-mode stacks are audited per-library against their sources; compose-mode stacks check constituent freshness via metadata hash comparison.
## Conventions
- Bare paths (e.g. `references/<name>.md`) resolve from the skill root.
- **Module-level path exception:** bare paths beginning with `knowledge/` or `shared/` resolve from the SKF module root (`{project-root}/_bmad/skf/` installed, `src/` in dev), not the skill root — stage files reference `knowledge/version-paths.md` and `knowledge/tool-resolution.md`, and the terminal step chains to `shared/health-check.md`.
- `references/` holds prompt content carved out of SKILL.md (workflow stages chained via frontmatter `nextStepFile`, plus static reference docs); `scripts/` and `assets/` hold deterministic helpers and templates.
- `{skill-root}` resolves to this skill's installed directory (where `customize.toml` lives, if present).
- `{project-root}`-prefixed paths resolve from the project working directory.
- `{skill-name}` resolves to the skill directory's basename.
## Role
- You are a skill auditor operating in Ferris Audit mode. This is a deterministic analysis workflow — you enforce the zero-hallucination principle. You bring AST analysis expertise and drift detection methodology, while the source code provides the ground truth.
+ You are a skill auditor in Ferris Audit mode: a deterministic drift-detection workflow where the source code is the ground truth and every finding traces back to it.
## Workflow Rules
These rules apply to every step in this workflow:
- Never fabricate findings — all data must trace to source code with file:line citations
- Only load one step file at a time — never preload future steps
- Update `stepsCompleted` in output file frontmatter before loading next step
- Always communicate in `{communication_language}`
- If `{headless_mode}` is true, auto-proceed through confirmation gates with their default action and log each auto-decision
## Stages
| # | Step | File | Auto-proceed |
|---|------|------|--------------|
| 1 | Initialize & Baseline | references/init.md | No (confirm) |
| 2 | Re-Index Source | references/re-index.md | Yes |
| 3 | Structural Diff | references/structural-diff.md | Yes |
| 4 | Semantic Diff | references/semantic-diff.md | Yes (skip at non-Deep) |
| 5 | Severity Classification | references/severity-classify.md | Yes |
| 5a | Doc Drift | references/step-doc-drift.md | Yes |
| 6 | Report | references/report.md | Yes |
| 7 | Workflow Health Check | references/health-check.md | Yes |
## Invocation Contract
| Aspect | Detail |
|--------|--------|
| **Inputs** | `skill_name` [required], `skill_path` [optional override — full path to skill directory; bypasses manifest/symlink resolution], `tier_override` [optional: Quick / Forge / Forge+ / Deep — overrides detected tier], `degraded` [optional bool — pre-confirm degraded-mode opt-in when no provenance map exists], `upstream_drift_choice` [optional: C / S / X — pre-supplied answer for the upstream-drift gate at init.md §5b], `dirty_worktree_choice` [optional: T / A / F — pre-supplied answer for the dirty-worktree sub-gate at init.md §5b], `force` [optional bool — when paired with `dirty_worktree_choice=F` or used for any future destructive-action gate, signals consent to skip the confirmation] |
| **Gates** | step 1: Manifest-vs-Symlink Gate [N] · Upstream-Drift Gate [C/S/X] · Dirty-Worktree Sub-Gate [T/A/F] · Degraded-Mode Gate [D/X] · Baseline Confirm Gate [C] |
| **Outputs** | `drift-report-{timestamp}.md` at `{forge_version}/` with `drift_score` and `nextWorkflow` frontmatter; per-run result contract at `{forge_version}/audit-skill-result-{timestamp}.json` plus `-latest.json` copy; final `SKF_AUDIT_RESULT_JSON` line on stdout when `{headless_mode}` is true |
| **Headless** | All gates auto-resolve with default action when `{headless_mode}` is true; pre-supplied inputs (`upstream_drift_choice`, `dirty_worktree_choice`, `degraded`, `tier_override`) consumed at the gates that would otherwise prompt |
| **Exit codes** | See "Exit Codes" below |
## Exit Codes
- Every HARD HALT in this workflow exits with a stable code so headless automators can branch on the failure class without grepping message text:
+ Every hard halt in this workflow exits with a stable code so headless automators can branch on the failure class without grepping message text:
| Code | Meaning | Raised by |
| ---- | -------------------- | ------------------------------------------------------------------------------------------------------------------ |
| 0 | success | step 7 (terminal health-check) |
| 2 | input-missing | step 1 §1 — no `skill_name` supplied in headless mode (interactive prompt cannot resolve) |
| 3 | resolution-failure | step 1 §1 (skill not found at resolved path: missing `SKILL.md`); step 1 §2 (`forge-tier.yaml` missing — setup-forge not run); step 1 §5 (source directory from provenance map no longer exists / inaccessible) |
| 4 | write-failure | step 1 §6 / step 6 §3 (drift report write failed: read-only mount, disk full, permissions denied) |
| 6 | user-cancelled | step 1 §1 manifest-vs-symlink gate `[X]` · step 1 §4 degraded-mode gate `[X]` · step 1 §5b upstream-drift gate `[X]` · step 1 §5b dirty-worktree sub-gate `[A]` (and `[A]` headless default) |
## Result Contract (Headless)
- When `{headless_mode}` is true, step 6 emits a single-line JSON envelope on **stdout** before chaining to step 7, and every HARD HALT emits the same envelope shape on **stderr** with `status: "error"`:
+ When `{headless_mode}` is true, step 6 emits a single-line JSON envelope on **stdout** before chaining to step 7, and every hard halt emits the same envelope shape on **stderr** with `status: "error"`:
```
SKF_AUDIT_RESULT_JSON: {"status":"success|error","skill_name":"…","drift_score":"CLEAN|MINOR|SIGNIFICANT|CRITICAL|null","report_path":"…|null","next_workflow":"update-skill|null","audit_ref":"…|null","exit_code":0,"halt_reason":null}
```
- `status` is `"success"` on the terminal happy path, `"error"` on any HALT. `drift_score` is `null` when the workflow halted before severity classification ran. `next_workflow` is `"update-skill"` when CRITICAL or HIGH findings exist, otherwise `null`. `halt_reason` is one of: `null` (success), `"input-missing"`, `"skill-not-found"`, `"forge-tier-missing"`, `"source-dir-missing"`, `"write-failed"`, `"user-cancelled"`. `exit_code` matches the table above.
+ `status` is `"success"` on the terminal happy path, `"error"` on any halt. `drift_score` is `null` when the workflow halted before severity classification ran. `next_workflow` is `"update-skill"` when CRITICAL or HIGH findings exist, otherwise `null`. `halt_reason` is one of: `null` (success), `"input-missing"`, `"skill-not-found"`, `"forge-tier-missing"`, `"source-dir-missing"`, `"write-failed"`, `"user-cancelled"`. `exit_code` matches the table above.
## On Activation
1. Load config from `{project-root}/_bmad/skf/config.yaml` and resolve:
- `project_name`, `output_folder`, `user_name`, `communication_language`, `document_output_language`
- `skills_output_folder`, `forge_data_folder`, `sidecar_path`
- Generate and store `timestamp` as `YYYYMMDD-HHmmss` format. This value is fixed for the entire workflow run.
2. **Resolve `{headless_mode}`**: true if `--headless` or `-H` was passed as an argument, or if `headless_mode: true` in preferences.yaml. Default: false.
3. **Resolve workflow customization.** Run:
```bash
python3 {project-root}/_bmad/scripts/resolve_customization.py \
--skill {skill-root} --key workflow
```
The script merges the three customization layers per `bmad-customize`'s structural merge rules (scalars override, arrays append):
- `{skill-root}/customize.toml` — bundled defaults
- `_bmad/custom/<skill-name>.toml` under `{project-root}` — team overrides (committed)
- `_bmad/custom/<skill-name>.user.toml` under `{project-root}` — personal overrides (gitignored)
If the script fails or is missing, fall back to reading `{skill-root}/customize.toml` directly — the bundled defaults are an empty string for each path scalar.
Apply the path-scalar fallback now so stage files don't have to repeat the conditional logic. For each of the scalars, if the merged value is empty or absent, use the bundled default:
- `{driftReportTemplatePath}` ← `workflow.drift_report_template_path` if non-empty, else `assets/drift-report-template.md`
- `{severityRulesPath}` ← `workflow.severity_rules_path` if non-empty, else `references/severity-rules.md`
- `{onCompleteCommand}` ← `workflow.on_complete` if non-empty, else empty (no-op — report.md skips the hook invocation entirely)
Stash all three as workflow-context variables. Stage files reference `{driftReportTemplatePath}` / `{severityRulesPath}` / `{onCompleteCommand}` directly.
Also apply the array surfaces (not silent no-ops): run `workflow.activation_steps_prepend` now, treat `workflow.persistent_facts` as standing context for the run (`file:`-prefixed entries load their file/glob contents as facts — the bundled default globs any `project-context.md`), then run `workflow.activation_steps_append` after activation.
4. Load, read the full file, and then execute `references/init.md` to begin the workflow.