public-surface-audit

public-surface-audit — Operator-Private Token Leak Scan

Scans the git-tracked file set (the public surface) for operator-private tokens that were supposed to stay in gitignored files (e.g. CLAUDE.local.md, companion store). After a public/private split, a front-door fix is not enough — a leaked username or absolute home path anywhere in the tracked set breaks the "public repo = model-agnostic methodology only" invariant.

While marketplace-gate Check 5 answers "is this repo broadly safe to publish?" (API keys, internal domains, license), public-surface-audit answers a narrower question: "did any operator-private token survive the public/private split into a tracked file?" It scans git ls-files only — gitignored files like CLAUDE.local.md are intentionally out of scope (they are the correct home for these tokens).

Triggers

• /public-surface-audit
• /public-surface-audit --target <repo path>
• /public-surface-audit --json (machine-parseable verdict for hook-gating — see Step 5)
• "Did I leak anything into the public repo?", "public surface audit", "private token scan"
• "Check tracked files for private tokens", "is my public/private split clean?"
• "Did any operator-private token survive into a tracked file?", "scan before publish"

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Scope — Tracked Files Only

This skill scans only git ls-files (committed/staged tracked files). Gitignored files are deliberately excluded — CLAUDE.local.md, the companion store, and local session data are the correct home for operator-private tokens, so finding them there is not a leak.

REPO_PATH="${ARGUMENTS#--target }"
REPO_PATH="${REPO_PATH:-$(pwd)}"
git -C "$REPO_PATH" rev-parse --is-inside-work-tree >/dev/null 2>&1 \
  || { echo "Not a git repo — public-surface-audit scans git-tracked files only. Aborting."; exit 1; }
echo "Target: $REPO_PATH"
git -C "$REPO_PATH" ls-files | wc -l | xargs echo "Tracked files:"

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Step 1. Pattern List (configurable)

The patterns are themselves operator-private — your real username and employer name must not be hardcoded here, on the public surface, or this skill would leak exactly what it hunts. So the literal values live in a gitignored source you supply (.claude/rules/.public-surface-patterns, or a section of CLAUDE.local.md) — one severity<TAB>regex per line. This SKILL.md carries only placeholders; the scan reads the gitignored file, never literals from this table. The skill dogfoods its own rule.

#	Token class	Severity	Placeholder (real value goes in the gitignored source)	Why private
1	Real username	HIGH	<your-unix-username>	Personal identity — must not appear on public surface
2	Company / employer asset name	HIGH	<company-asset> (alternation OK)	Company-confidential, leak-forbidden
3	Operator absolute home path	MED	/Users/[a-z0-9_-]+/ (generic — carries no literal name)	Machine-bound, leaks username + local layout
4	Companion-store name	LOW	<companion-store-name>	Private companion store — methodology should not name it
5	Operator-private script / handoff name	LOW	<private-script>, <private-dir>/	Operator-specific wiring, belongs in CLAUDE.local.md

Severity meaning:

• HIGH — real name or company asset. A leak is a confidentiality / identity exposure. Block publish.
• MED — absolute home path. Leaks username + local filesystem layout; also a portability bug.
• LOW — companion-store / private-wiring name. Methodology should be model-agnostic; naming a private store is drift, not a confidentiality breach.

Setup: put your real values in the gitignored pattern source (one severity<TAB>regex per line); the scan reads that file, never literals from this SKILL.md. If the source is absent, the scan reports NOT CONFIGURED — not CLEAN. A missing pattern file must never masquerade as a clean bill of health (that would be a silent failure: "nothing scanned" misread as "nothing leaked"). To declare "I genuinely have no private tokens", create the file empty — an empty file is an explicit CLEAN, an absent file is unconfigured.

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Step 2. Allowlist (legitimate references)

Some tracked files legitimately reference otherwise-private tokens — the scan must not flag these as leaks. Maintain an allowlist of file path :: token pairs. A match is suppressed only when both the file and the token are on the allowlist row.

Tracked file	Allowed tokens	Reason
.gitignore	companion-store name, sync-script name	Must name what it ignores
your sync script (e.g. scripts/<sync-script>)	companion-store name, operator-dir names, home path	The sync script's whole job is the companion store
an install-template rules file	home path, companion-store name	Install template — the install path is its content
a doc describing the companion-store pattern	the *-be pattern (no literal store name)	Documents the pattern generically

Allowlist rule: a hit on file F matching token T is suppressed iff a row exists with file == F and T in that row's allowed tokens. Everything else is reported. Keep the allowlist tight — when in doubt, report and let the user confirm. Genuinely model-agnostic mentions (the *-be companion pattern without the literal store name) should not require allowlisting because they do not match a literal private token.

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Step 3. Scan

For each pattern in Step 1, grep the tracked set, then drop allowlisted hits.

cd "$REPO_PATH" || exit 1
# Build the tracked-file list once.
git ls-files > /tmp/_psa_tracked.txt

# Load your real patterns from the gitignored source (one "severity<TAB>regex" per line).
PATTERN_SRC="${PSA_PATTERNS:-.claude/rules/.public-surface-patterns}"
# Absent file ≠ CLEAN. An absent file is unconfigured (silent-failure risk); an EMPTY file is an
# explicit "no tokens to protect" → CLEAN. Distinguish the two.
[ -e "$PATTERN_SRC" ] || { echo "⚪ NOT CONFIGURED: no pattern source at $PATTERN_SRC. Create it (empty = explicit CLEAN) before trusting any verdict. Not scanning."; exit 2; }

# One grep pass per pattern row; the regex comes from the file, never hardcoded here.
while IFS=$'\t' read -r severity regex; do
  [ -z "$regex" ] && continue
  grep -nIE "$regex" $(cat /tmp/_psa_tracked.txt) 2>/dev/null | sed "s/^/[$severity] /"
done < "$PATTERN_SRC"

For each pattern, run grep -nIE "<regex>" $(git ls-files):

• -n → line numbers (required for file:line output)
• -I → skip binary files
• -E → extended regex (alternation in the pattern table)

Then remove any hit whose file + matched token is on the Step 2 allowlist. Do this for every pattern row before producing the report — do not stop at the first HIT.

Binary / generated carve-out: -I already skips binaries. Additionally note (do not auto-suppress) hits inside generated artifacts (e.g. paper/*.html exported from a private source) — these are real leaks on the public surface and must be reported, but the fix is "regenerate from a sanitized source", not "edit the HTML by hand". Flag them with a (generated artifact) note.

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Step 3b. FP Hygiene — Placeholder & Example Exclusion

A scan that flags its own placeholders erodes trust. Two value-shape classes are never real leaks and are dropped before the report — imported from gstack-redact's canonical-example allowlist, scoped in PSA's direction to the matched token (not the whole line, so a real leak sharing a substring still reports):

• Angle-bracket placeholders — the matched token is itself a placeholder (<your-unix-username>, <company-asset>, {project}). PSA dogfoods these in Step 1; the scan must not report them as leaks.
• Canonical dummy values — the matched token is a documented example/dummy (EXAMPLE, dummy, changeme, REDACTED, xxxx, AWS-doc keys like AKIAIOSFODNN7EXAMPLE). A high-entropy example is not a secret.

# FP-hygiene tests the MATCHED TOKEN only — never the whole line. A line-level `grep -v` would
# suppress a real leak that merely *mentions* an example (e.g. `user=<realname> # see EXAMPLE.md`),
# violating PSA's "allowlist tight" rule. So extract the matched span per hit and drop it only when
# the span is *entirely* a placeholder/example (anchored ^…$).
PLACEHOLDER='^(<[a-z0-9_-]+>|\{project\}|EXAMPLE|dummy|changeme|REDACTED|xxxx)$'
grep -nIE "$regex" $(cat /tmp/_psa_tracked.txt) 2>/dev/null | while IFS= read -r hit; do
  tok=$(printf '%s' "$hit" | grep -oiE "$regex" | head -1)
  printf '%s' "$tok" | grep -qiE "$PLACEHOLDER" && continue   # token IS a placeholder → drop
  printf '%s\n' "$hit"
done

This differs from the Step 2 allowlist: Step 2 suppresses by file::token legitimacy, Step 3b by token value-shape. Both run — Step 2 then Step 3b. Keep it tight (PSA's "allowlist tight" rule): if a token only contains an example substring but is otherwise a real private value, it still reports.

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Step 4. Report

public-surface-audit — Operator-Private Token Scan
━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━
  Target: {REPO_PATH}   |   Tracked files scanned: {N}

  🔴 HIGH  ({count})
    {file}:{line}  →  {matched token}   [class: username | company asset]
  🟠 MED   ({count})
    {file}:{line}  →  {matched token}   [class: absolute home path]
  🟡 LOW   ({count})
    {file}:{line}  →  {matched token}   [class: companion-store | private wiring]

  Allowlist-suppressed: {count} hit(s) (legitimate references — not leaks)

  Verdict:
    ⚪ NOT CONFIGURED — pattern source absent (nothing scanned — NOT a clean result; set up first)
    🟢 CLEAN        — pattern source present (incl. empty), 0 HIGH + 0 MED + 0 LOW (after allowlist)
    🟡 REVIEW       — 0 HIGH + 0 MED, LOW-only (drift, not a breach)
    🔴 LEAK         — 1+ HIGH or 1+ MED (block publish / fix before commit)
━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━

Per HIGH/MED hit, append a one-line prescription:

• HIGH (username/company) — move the line to CLAUDE.local.md (or regenerate the artifact from a sanitized source); never edit-in-place if it is a generated file.
• MED (absolute path) — replace with a relative path, a ~-anchored path, or a {project} placeholder; absolute home paths are also a portability bug for external clones.
• LOW (companion-store/wiring) — rephrase to the model-agnostic pattern (e.g. "a private companion store" / "the *-be companion pattern") instead of the literal name, unless the file is the .gitignore / sync script that must name it (allowlist those).

Simplification guard: 🟢 CLEAN → collapse the report to one line: "public surface clean — 0 private tokens in {N} tracked files (X allowlist-suppressed)." Do not print empty severity buckets.

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Step 5. Machine Output (--json) — Hook-Gateable Verdict

By default PSA prints the Step 4 human report. With --json, emit a machine-parseable verdict so a pre-publish / pre-push hook can gate on counts mechanically — turning PSA from advisory into enforceable (FH's "enforcement is a hook, not a prompt" principle). Imported from gstack-redact --json.

{
  "target": "{REPO_PATH}",
  "tracked_files": 0,
  "findings": [
    {"file": "path", "line": 42, "token": "<matched>", "severity": "HIGH", "class": "username"}
  ],
  "counts": {"HIGH": 0, "MED": 0, "LOW": 0, "suppressed": 0},
  "verdict": "CLEAN"
}

verdict is one of CLEAN | REVIEW | LEAK | NOT_CONFIGURED (same thresholds as Step 4). verdict is authoritative — never gate on counts alone: a counts-only check (HIGH==0 && MED==0) misreads NOT_CONFIGURED (which also has zero counts) as a pass. A caller blocks when verdict is LEAK or NOT_CONFIGURED — an unconfigured scan is not a pass (the same silent-failure guard as the human path: absence ≠ CLEAN).

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Connected Skills

Situation	Connected skill
Broader pre-publish repo readiness (README, license, API keys)	/marketplace-gate (Check 5 Public Safety is the wide net; this skill is the private-token detail)
A leak is a recurring process gap, not a one-off	log via field-harvest → candidate #rule-candidate
Where should the leaked content actually live?	/asset-placement-gate (hub vs project vs CLAUDE.local.md)
Phantom refs / stale links on the same surface	/phantom-quench (forward axis — orthogonal to this leak axis)

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External User Environment Adaptation

Usable standalone — no hub clone required.

• No companion store / no operator-private tokens → create the pattern source empty to declare this explicitly; the scan then reports CLEAN. Leaving the file absent instead yields NOT CONFIGURED (a deliberate distinction — absence is "unknown", not "clean"). The skill is only useful once you have a public/private split to protect.
• No .gitignore allowlist needs → Step 2 allowlist may be empty; every hit is then reported.

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Done When

Step 1 pattern list confirmed (defaults shown / user-adapted)
+ Step 2 allowlist applied
+ Step 3 scan run for every pattern over git ls-files (tracked only — gitignored excluded)
+ Step 4 report output: per-hit file:line + token + severity, plus overall verdict
+ "public-surface-audit Complete" declaration output

Verdict: CLEAN (0 tokens after allowlist) | REVIEW (LOW-only — drift, prescriptions noted) | LEAK (1+ HIGH or 1+ MED — block publish, prescriptions attached).

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Operating Notes

• Tracked-only is the point: never scan gitignored files. A token in CLAUDE.local.md is correct placement, not a leak — scanning it would produce false LEAK verdicts and erode trust in the skill.
• Patterns are data, not code: the Step 1 table is the configurable surface. A user with a different username/employer/companion-store edits the table; the scan logic is unchanged.
• Generated artifacts are real leaks: an exported HTML/PDF carrying a username is still a public-surface leak even though hand-editing it is wrong — report it, prescribe "regenerate from sanitized source".
• Allowlist tight, not loose: when unsure whether a reference is legitimate, report it. A false LEAK the user dismisses is cheaper than a real leak suppressed by an over-broad allowlist.
• Auto-redact deliberately not imported: gstack-redact offers --auto-redact (rewrite + diff). PSA's philosophy is report + prescribe; the human decides where the line goes — auto-redacting a HIGH (username/company) hit would pre-empt that judgment, and auto-editing a generated artifact is explicitly wrong (regenerate from source). If ever imported, restrict to the MED absolute-home-path class only (mechanically safe: /Users/<user>/ → ~/ or {project}), never HIGH, never generated files.

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Sister-Asset Provenance

Step 3b (FP hygiene) and Step 5 (--json) were imported from garrytan/gstack gstack-redact (lib/redact-engine.ts) during a hands-on sister-asset cross-audit (2026-06-06; see tracks/_audit/session_2026_06_06_gstack_sister_handson.md). They are adapted to PSA's operator-IP ontology — gstack-redact's generic secret/PII classes (AWS / PEM / JWT / hostname) stay out of PSA's scope (orthogonal coverage: PSA = operator-IP leak, redact = generic secret). The reverse direction (PSA's operator private-codename + bare-username classes, which gstack-redact structurally cannot detect) is a candidate contribution back to gstack.