agentmods.dev

agentcov AGENTS.md

Project-specific instructions for agentcov, a tool that records which lines an AI coding agent reads and turns that activity into coverage reports. They explain its code structure, event pipeline, and development practices.

In plain words
What is it for?
Use them when changing agent activity parsing, coverage generation, hooks, command handling, or tests for the agentcov package.
Why use it?
They give an agent the repository context needed to make consistent changes and avoid duplicating fixes across different input sources.

Instructions file for CodexOpenCode

50 27d ago A scan 2,195 tokens original Apache-2.0
View the source file trailofbits/agentcov
Install

Getting it into your agent

One page per mod, every tool's command on it. A separate URL per tool would split the same page into five that compete with each other.

agentmods
npx agentmods add instructions/trailofbits/agentcov/agents-md
Clone the repo
git clone --depth 1 https://github.com/trailofbits/agentcov

Made for: Codex, OpenCode.

Per session 2,195 This file is loaded in full into every session.
When invoked 2,195 The same file — it is already loaded in full.
Security scan A 0 findings. Scan, not verified.
Origin original No closer match found in the catalogue.
Token cost

What it costs to keep this loaded

Counted locally with the o200k_base tokenizer, which is exact for GPT models; Claude uses its own tokenizer and its counts differ. Treat this as one consistent yardstick across the catalogue rather than a bill. Prices are per million input tokens.

ModelPer sessionOnce invoked
Fable 5 $0.02195 $0.02195
Opus 5 $0.01097 $0.01097
Sonnet 5 $0.00439 $0.00439
Haiku 4.5 $0.00219 $0.00219

Measured 3d ago against content hash 6d4be132bbca, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

agentcov AGENTS.md scanned grade A with 0 findings against 26 rules in 11 categories — prompt injection, anti-refusal, data exfiltration, privilege escalation, supply chain, agent snooping, system-prompt leakage, SSRF and excessive agency — measured 3d ago.

A static scan of the body, not an audit. Every finding is printed with the line that produced it so you can judge whether it matters here. A mod is markdown that instructs an agent; that is exactly why what it instructs is worth reading.

Nothing flagged

None of the 26 patterns this scan looks for appear in this file: no shell pipes, no recursive deletes, no credential paths, no hidden text, no instruction-override or anti-refusal phrasing, no agent-config snooping. That is not a guarantee, it is the absence of the things that are checkable.

AGENTS.md · 210 lines

How it starts

The opening of the file, as written. The whole thing — 210 lines — stays where its author put it; the contents beside it link to each section on GitHub.

AGENTS

Repo Overview

agentcov records which lines of a repository an AI coding agent actually read, then renders that as coverage. The package is agentcov; the repository is trailofbits/agentcov.

There are two ways activity gets in, and they converge immediately:

  • live hooks: Codex calls agentcov hook ... on each tool use
  • backfill: a Codex, Claude Code, or Pi session transcript is replayed after the fact

Both produce the same hook-shaped payload dict, so everything downstream of events_from_payload is shared. When you fix a parsing bug, fix it once in the shared layer rather than per agent.

The pipeline is:

payload -> parser -> CoverageEvent -> .agentcov/events.jsonl
        -> build_coverage -> .agentcov/coverage.json -> lcov / gcov / html / summary

Modules under src/agentcov:

  • cli.py: argparse wiring and command handlers; every subcommand lands here
  • hooks.py: Codex hook install/uninstall, and events_from_payload, the single entry point that turns a payload into CoverageEvents
  • parser.py: shell command parsing (sed, head, tail, cat, awk, sort, pipelines, simple for loops) and rg/grep output parsing
  • models.py: LineRange, ParsedObservation, CoverageEvent, and the identity tuple used for dedupe
  • storage.py: locked append to events.jsonl, atomic coverage.json write
  • aggregate.py: events to per-file/per-line coverage, attribution, and session rollups
  • report.py: LCOV, gcov, self-contained HTML, summary, and unread output
  • config.py: .agentcov.toml loading and exclude matching
  • git.py: repo root discovery, tracked-file inventory, line counts
  • paths.py: path normalization relative to the repo root
  • transcripts.py: locating session JSONL files on disk per agent
  • claude_transcript.py, codex_transcript.py, pi_transcript.py: per-agent transcript record to payload translation
  • backfill.py: orchestrates transcript replay and agent auto-detection
  • importers.py: agent-coverage-style JSON import

Read the full file on GitHub · 210 lines

Changes

What this file has done since we first saw it

Hashed on every crawl. A supply-chain change to an agent config is a question of when, not whether, so the history is kept rather than the latest state alone.

  1. 3d ago First seen · 210 lines · 2,195 tokens per session scan A 6d4be132bbca

Subscribe to this mod's changes

agentcov AGENTS.md is an instructions file published in the GitHub repository trailofbits/agentcov (50 stars, last pushed 27d ago), licensed Apache-2.0. It adds 2,195 tokens to every session, about $0.0110 per session on Opus 5. A static security scan graded it A with 0 findings. No closer match exists in the catalogue, so it is treated as the original; first seen 2026-08-30.

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