interface:
  display_name: "Trailmark Review Gate"
  short_description: "Check code changes for structural security regressions"
  icon_small: "assets/trail-of-bits-mark.svg"
  icon_large: "assets/trail-of-bits-mark.svg"
  brand_color: "#D83A34"

# Gate Rules

Start with deterministic, conservative rules. A triggered rule creates a
review obligation; it does not prove a vulnerability.

| Rule | Verdict | Why it matters |
|---|---|---|
| New untrusted entrypoint | `FAIL` | Expands external attack surface |
| New path from untrusted entrypoint to sensitive sink | `FAIL` | Creates a candidate exploit path |
| Removed auth, validation, or sanitization call on reachable path | `FAIL` | Common regression in fixes and feature PRs |
| Newly tainted privilege-boundary node | `FAIL` | Trust transition now handles untrusted data |
| Blast radius growth above threshold | `WARN` | A bug may now affect more code |
| Complexity growth on tainted or boundary node | `WARN` | Risky logic became harder to review |
| New unresolved, proxy, or dynamic call on reachable path | `WARN` | Graph uncertainty increased in a risky area |
| Dead security function removed | `WARN` | May be cleanup or accidental security removal |

## Default Thresholds

Use these defaults unless the repository has stricter local rules:

| Signal | Default threshold |
|---|---|
| Blast radius growth | `+5` downstream reachable nodes or `+25%`, whichever is larger |
| Complexity growth | cyclomatic complexity `+3` on tainted, boundary, or entrypoint-reachable node |
| Sensitive sink path | any new path from untrusted entrypoint to sink |
| Unresolved/proxy growth | any new unresolved/proxy edge on an entrypoint-reachable path |

Thresholds are intentionally conservative. They reduce noise while still
catching structural changes that line diffs often understate.

## Sensitive Sink Categories

Flag new reachable paths to:

- value transfer
- authorization or role decisions
- persistence or state writes
- parsing or deserialization
- cryptographic keys, sessions, or signatures
- external process, network, or file operations
- upgrade, plugin, hook, or dynamic dispatch mechanisms

## Rule Precedence

Use the most severe triggered verdict:

1. `UNKNOWN` if Trailmark cannot produce adequate evidence
2. `FAIL` if any fail rule triggers
3. `WARN` if any warn rule triggers
4. `PASS` only if evidence is adequate and no rule triggers

If both `UNKNOWN` and `FAIL` seem applicable, emit `UNKNOWN` and list the
suspected fail condition as a manual review target.

# Output Format

Use Markdown unless the user asks for JSON.

```markdown
# Trailmark Review Gate

## Verdict

Gate: PASS | WARN | FAIL | UNKNOWN
Confidence: High | Medium | Low

## Triggered Rules

| Rule | Verdict | Evidence |
|---|---|---|

## Structural Changes

| Change | Before | After | Review target |
|---|---|---|---|

## Entrypoint And Reachability Changes

## Privilege And Taint Changes

## Blast Radius And Complexity Changes

## Limitations

## Recommended Reviewer Actions
```

## Evidence Requirements

For each triggered rule, include:

- changed node or edge identifier
- source file or symbol when available
- entrypoint path when relevant
- before/after metric when metric-based
- manual review target

## Wording Requirements

- Say "gate fired" instead of "vulnerability found".
- Say "review target" instead of "exploit path" unless exploitability is
  separately established.
- Say `UNKNOWN` when Trailmark fails or parser support is too incomplete.
- Do not claim a `PASS` means the change is secure.

# Review Integration

Use the review gate packet as supporting evidence for a human branch review.
It should be attached to, pasted into, or summarized alongside line-level
review notes.

## With Differential Review

Use `differential-review` for line-level analysis and this skill for structural
signals. Recommended order:

1. Run `differential-review` to identify risky changed files and functions.
2. Run `graph-evolution` and `trailmark-review-gate` on the same before/after
   range.
3. Cross-reference `FAIL` and `WARN` rules with changed source lines.
4. Add the gate packet to the review notes.
5. Treat `PASS` as "no configured graph rule fired", not as approval.

## With PR Review Processes

When an engagement has a separate PR review workflow, include:

- gate verdict
- triggered rules table
- exact changed nodes and paths
- manual reviewer actions
- limitations

Do not use GitHub write actions unless the review process explicitly asks for
them. The packet is review evidence, not an automatic merge decision.

## With Remediation Review

For a fix commit:

- compare vulnerable base to the proposed fix
- check that affected reachable paths changed as expected
- check that no new entrypoint or sensitive-sink path appeared
- report `UNKNOWN` if graph evidence cannot confirm the structural change

This does not replace semantic verification that the original finding was
fixed.