Fork Ancestry

FORK_ANCESTRY Skill

Trigger Pattern: Always (run during recon TASK 0, not breadth) Inject Into: Recon agent only (meta_buffer.md enrichment) Purpose: Detect known parent codebases and inherit their historical vulnerability patterns.

1. Detect Fork Indicators

Grep the codebase for known parent signatures:

Git-based detection (complements code-pattern matching — catches forks that renamed all identifiers). Skip if REPO_SHAPE: squashed_import in build_status.md — single-commit repos have no meaningful git metadata.

• Parse .gitmodules for submodule URLs pointing to known parent repos
• Check git remote -v for origin URLs matching known parent organizations (compound-finance, Uniswap, aave, sushiswap, curvefi, yearn, OlympusDAO, balancer)
• If a git-URL match is found but NO code-pattern match exists, flag as GIT_ONLY_FORK — the fork likely renamed all identifiers, which warrants deeper divergence analysis

Output: List of detected parents with confidence level (HIGH: 3+ patterns, MEDIUM: 2 patterns, LOW: 1 pattern, GIT_ONLY: git URL match but no code patterns).

2. Query Known Parent Issues

For each detected parent (confidence MEDIUM or HIGH):

2a. Solodit Search (two queries, run in parallel)

// Query 1: Known high-quality issues
search_solodit_live(
  protocol="{parent_name}",
  impact=["HIGH", "CRITICAL"],
  language="Solidity",
  quality_score=3,
  sort_by="Quality",
  max_results=15
)
// Query 2: Rare/unusual patterns specific to fork divergences
search_solodit_live(
  keywords="{parent_name} fork modified divergence",
  impact=["HIGH", "MEDIUM"],
  language="Solidity",
  sort_by="Rarity",
  max_results=10
)

2b. Tavily Search

tavily_search(query="{parent_name} smart contract vulnerability exploit audit finding 2024 2025 2026")

2c. Known Issue Catalog

Compile results into:

Applicability criteria:

• YES: Fork retains the vulnerable code path unchanged
• NO: Fork modified the vulnerable code path (document what changed)
• CHECK: Cannot determine without deeper analysis (flag for breadth agent)

2d. Hardcoded Known-Issue Floor (Web Search Fallback)

If Solodit AND Tavily BOTH fail, use this minimum catalog -- check EACH applicable parent.

This floor is keyed on the parent's TYPE (generic mechanism), NOT on any specific protocol name — brand-keyed rows are prohibited (a floor row naming a specific protocol is the confirmed benchmark-contamination vector; see the HARD no-overfit rule). Classify the detected parent (from Section 1) into a type below and check the generic known-issue class; use at most one illustrative brand only in prose, never as the row key.

Note: This floor lists generic known-issue CLASSES by parent type only — it is minimum coverage, not exhaustive, and NOT a substitute for the live-searched Solodit/Tavily results (2a/2b). Real research typically surfaces several more issues specific to the actual parent.

3. Divergence Analysis

For each detected parent:

3a. Identify What Changed

Compare fork vs parent in security-critical paths:

Focus on:

• Modified access control (added/removed roles, changed modifiers)
• Changed mathematical formulas (fee calculations, exchange rates, reward distribution)
• Parameter semantic verification: When the parent has a mathematical specification, verify that each core parameter carries the same mathematical meaning in the fork — not just the same name and numeric range. Forks may store a raw value where the parent stores a derived form (e.g., raw coefficient vs. coefficient scaled by a function of pool dimensions). Compare the fork's formula usage against the parent's specification to confirm the encoding convention matches.
• Added external dependencies (new oracles, new tokens, new protocols)
• Removed safety checks (validation removed, guard removed)
• Changed state variable types or visibility

3b. New Attack Surface from Divergence

For each modification:

• Does the change introduce a NEW vulnerability not in the parent?
• Does the change REMOVE a parent fix/mitigation?
• Does the change create an INCONSISTENCY with parent's invariants?

4. Output to meta_buffer.md

Append to {SCRATCHPAD}/meta_buffer.md:

## Fork Ancestry Analysis

### Detected Parents
| Parent | Confidence | Patterns Found |
|--------|-----------|---------------|

### Inherited Vulnerabilities to Verify
| # | Parent Issue | Severity | Location in Fork | Status |
|---|-------------|----------|------------------|--------|
| 1 | {issue} | {severity} | {fork location} | CHECK / VERIFIED_SAFE / VULNERABLE |

### Fork Divergences (Security-Critical)
| # | Component | Change | New Risk? |
|---|-----------|--------|-----------|

### Questions for Breadth Agents
1. {derived from inherited vulnerabilities}
2. {derived from divergence analysis}

Step Execution Checklist (MANDATORY)