New to Claude Skills? Learn how to install them →

trailofbits on GitHub

Trailmark Structural Analysis

Free

Comprehensive structural analysis for codebases.

by trailofbits6.5k stars on trailofbits/skills
2 views
Updated Aug 10, 2026
Get this skill

Free · Opens the source repo

What Trailmark Structural Analysis does

Trailmark Structural Analysis is a powerful tool designed for developers and security analysts who require detailed insights into the structural aspects of their codebases. By building a Trailmark graph and executing a series of pre-analysis passes, this skill provides a wealth of information, including hotspots, taint analysis, blast radius, privilege boundaries, and attack surface metrics. This is particularly useful during the initial phases of code analysis, where understanding the intricate relationships and vulnerabilities within the code is crucial.

The skill operates by utilizing the engine.preanalysis() function, which performs four distinct analysis passes that cross-reference each other to ensure comprehensive coverage. This multi-faceted approach allows users to identify critical nodes and potential vulnerabilities that might be overlooked with simpler analysis methods. The output includes version-gated data from Trailmark 0.4 and 0.5, such as proxy counts and type/reference summaries, enhancing the analysis for users with the latest versions of Trailmark installed.

Trailmark Structural Analysis is especially beneficial when conducting a thorough audit of complex codebases or when specific targets require in-depth structural data. It is designed for users who are already familiar with the Trailmark ecosystem and need to leverage its capabilities to enhance their security assessments or code reviews. The skill provides detailed outputs that can guide prioritization in audits and help in understanding the attack surface of applications.

However, this skill is not intended for quick overviews or simple queries. Users looking for a high-level summary or those working with small files may find it excessive. Instead, it is best suited for scenarios where deep analysis is necessary, ensuring that critical vulnerabilities are not missed during the review process.

When to use it

Use this skill when you need a detailed structural analysis of a codebase, particularly during the initial phases of a security review or audit.

When not to use it

Avoid this skill for quick summaries or when analyzing very small files where detailed structural analysis may not yield significant insights.

What you can build with it

Security Audit Preparation

Utilize the skill to gather detailed structural insights before conducting a security audit, ensuring all vulnerabilities are identified.

Complex Codebase Analysis

When analyzing large and complex codebases, this skill provides essential data to prioritize areas of concern effectively.

Version-Specific Insights

If using Trailmark 0.4 or higher, leverage the skill to access enriched data that highlights specific vulnerabilities and relationships.

How to install Trailmark Structural Analysis

View source

1. Install with the skills CLI

npx skills add trailofbits/skills/trailmark-structural --agent claude-code

2. Or install it manually

Download the skill folder and drop it into ~/.claude/skills/ for all projects, or .claude/skills/ to scope it to one repo. Restart Claude Code so it picks up the new skill.

Anthropic's agentic coding CLI, and the reference implementation of Agent Skills. Drop a skill folder into ~/.claude/skills and Claude Code loads it automatically whenever a task matches the skill's description. Claude Code docs

Inside SKILL.md

Written by trailofbits

Trailmark Structural Analysis

Builds a Trailmark graph and runs engine.preanalysis() to compute all four pre-analysis passes. The core workflow is v0.2-safe; v0.4-only details are included only after checking method availability, and newer builds enrich the same output (0.5.0+ adds an attributes key to attack-surface entries and proxy.external:* nodes from .trailmark/links.toml) without any workflow change.

When to Use

  • Vivisect Phase 1 needs full structural data (hotspots, taint, blast radius, privilege boundaries)
  • Detailed pre-analysis passes for a specific target scope
  • Generating complexity and taint data for audit prioritization
  • Inspecting proxy/unresolved-call counts, subgraph edges, or type-reference summaries when Trailmark 0.4.0+ is installed

When NOT to Use

  • Quick overview only (use trailmark-summary instead)
  • Ad-hoc code graph queries (use the main trailmark skill directly)
  • Target is a single small file where structural analysis adds no value

Rationalizations to Reject

RationalizationWhy It's WrongRequired Action
"Summary analysis is enough"Summary skips taint, blast radius, and privilege boundary dataRun full structural analysis when detailed data is needed
"One pass is sufficient"Passes cross-reference each other — taint without blast radius misses critical nodesRun all four passes
"Tool isn't installed, I'll analyze manually"Manual analysis misses what tooling catchesReport "trailmark is not installed" and return
"Empty pass output means the pass failed"Some passes produce no data for some codebases (e.g., no privilege boundaries)Return full output regardless
"A v0.4 field is always present"Users may still have Trailmark 0.2.x installedProbe with hasattr() before querying v0.4-only methods

Usage

The target directory is passed via the args parameter.

Execution

Step 1: Check that trailmark is available.

trailmark analyze --help 2>/dev/null || \
  uv run trailmark analyze --help 2>/dev/null

If neither command works, report "trailmark is not installed" and return. Do NOT run pip install, uv pip install, git clone, or any install command. The user must install trailmark themselves.

Optionally record the version:

trailmark --version 2>/dev/null || uv run trailmark --version 2>/dev/null || true

Do not fail if this command is missing; use API feature probes below.

Step 2: Detect languages with Trailmark's parse API.

python3 - "{args}" <<'PY'
import json
import sys

try:
    from trailmark.parse import detect_languages  # canonical location since 0.3.x
except ModuleNotFoundError:
    # v0.2.x predates trailmark.parse; the same function lives in query.api
    from trailmark.query.api import detect_languages

print(json.dumps(detect_languages(sys.argv[1])))
PY

If the import fails, rerun the same snippet with uv run python - "{args}". If the result is [], report "Trailmark found no supported languages under target" and return.

Step 3: Run the full structural analysis via QueryEngine.

Run this snippet with python3. If the import fails, rerun the same snippet under uv run python - "{args}".

python3 - "{args}" <<'PY'
import json
import sys

try:
    from trailmark.parse import detect_languages  # canonical location since 0.3.x
except ModuleNotFoundError:
    # v0.2.x predates trailmark.parse; the same function lives in query.api
    from trailmark.query.api import detect_languages

from trailmark.query.api import QueryEngine

target = sys.argv[1]
languages = detect_languages(target)
engine = QueryEngine.from_directory(target, language="auto")
preanalysis = engine.preanalysis()

def summarize_subgraph(name: str, limit: int = 25) -> dict[str, object]:
    nodes = engine.subgraph(name)
    summary = {
        "count": len(nodes),
        "sample_ids": [node["id"] for node in nodes[:limit]],
    }
    if hasattr(engine, "subgraph_edges"):
        summary["edge_count"] = len(engine.subgraph_edges(name))
    return summary

graph = json.loads(engine.to_json())
nodes = graph.get("nodes", {})
proxy_nodes = [
    node_id for node_id, node in nodes.items()
    if node.get("kind") == "proxy" or node.get("origin") == "proxy"
]

payload = {
    "languages": languages,
    "summary": engine.summary(),
    "preanalysis": preanalysis,
    "attack_surface": engine.attack_surface()[:25],
    "hotspots": engine.complexity_hotspots(10)[:25],
    "proxy_nodes": proxy_nodes[:25],
    "subgraphs": {
        name: summarize_subgraph(name)
        for name in engine.subgraph_names()
    },
}

if hasattr(engine, "type_references"):
    payload["type_reference_samples"] = {
        node_id: engine.type_references(node_id)[:10]
        for node_id in list(nodes)[:25]
    }

print(json.dumps(payload, indent=2))
PY

Step 4: Verify the output.

The output should include:

  • languages
  • summary
  • preanalysis
  • hotspots (possibly empty)
  • proxy_nodes (empty on v0.2.x or when there are no unresolved calls; on 0.5.0+ may include proxy.external:* entries declared in .trailmark/links.toml)
  • subgraphs with counts and sample IDs

On Trailmark 0.5.0+, attack_surface entries may carry an attributes object (e.g. solidity_visibility, solidity_overridden_by). Pass it through unchanged — downstream consumers use it to rank entrypoints.

Some subgraphs may have zero nodes for some codebases (this is normal). Return the full JSON payload regardless.

Frequently asked questions about Trailmark Structural Analysis

Similar skills