codex-readcov

name

codex-readcov

description

Use when you need the host codex-readcov command to inspect transcript-recorded file-read actions for a Codex CLI thread or rollout JSONL file: read counts, snapshot/delta windows, path filtering, paths-only output, or Unix composition of read path lists. Do not use for test coverage, file search, summarizing file contents, operating-system audit logs, or proving that commands succeeded or every file access was observed.

Codex Readcov

Purpose

Use this skill when you need to inspect file-read actions reconstructed from a Codex thread's rollout transcript.

Assume codex-readcov is installed on the host. It reads transcripts; it does not inspect live process file descriptors, scrape shell output, measure test coverage, or summarize file contents.

Model

• A target is a Codex thread id or a rollout JSONL path.
• top counts reads across a transcript.
• snapshot records the current transcript cursor.
• delta counts reads appended after a snapshot, or between two snapshots.
• Path operands filter reported reads; they do not define a coverage universe.
• Counts classify recorded commands; they do not verify command success or file contents returned to the model.
• Current exec wrapper calls are parsed as JavaScript. If nested command arguments are constructed dynamically, readcov fails instead of returning incomplete coverage as zero.

For the current thread, use CODEX_THREAD_ID when it is available:

THREAD=${CODEX_THREAD_ID:?CODEX_THREAD_ID is not set}

Patterns

Snapshot before a work interval:

codex-readcov snapshot THREAD_ID > before.json

Inspect reads appended since that snapshot:

codex-readcov delta before.json

Scope the result only when needed:

codex-readcov delta before.json PATH [PATH...] --limit 20

Use an explicit end snapshot when the window must be fixed:

codex-readcov snapshot THREAD_ID > after.json
codex-readcov delta before.json --to after.json PATH --json

Use top only when the full transcript summary is more useful than a time window:

codex-readcov top THREAD_ID PATH --limit 20

Produce path lists for Unix set operations:

codex-readcov delta before.json PATH --paths-only --limit 0 | sort > read.txt

References

• Read references/coverage-semantics.md when what counts, transcript limitations, live rollout behavior, or parser dependency matters.
• Read references/snapshot-windows.md when choosing between top, snapshot, delta, explicit --to, or line ranges.
• Read references/path-composition.md when path filtering, --paths-only, JSON output, negative coverage, or multi-thread set operations matter.
• Read references/coordination-principles.md when deciding how read coverage composes with persisted goals, live wakes, native controls, or partial skill availability.
• Read references/coordination-recipes.md for command combinations involving coverage audits, worker review, negative coverage, or external managers.
• Read references/operational-caveats.md when reliability limits, live rollouts, or cross-surface consistency matter.

Conventions

• Prefer snapshot plus delta for a work interval.
• Take the first snapshot before the work interval starts.
• Use top only when a full-transcript summary is more useful than a time window.
• Use path operands for an intentionally scoped view, not as proof that other paths were unread.
• Use --paths-only --limit 0 before sort, comm, or uniq.
• Keep negative coverage, union, and intersection outside codex-readcov.
• Use --json when another program will parse output.
• Do not present results as verified command success, model context exposure, OS-level audit data, or proof of every file access.