# Agent Instructions

## Work tracking

No durable tracker or plan file is configured in this repository. Treat the user request as the active work authority unless a future shared tracker, issue, or plan is explicitly named. Do not create local issue mirrors, PLAN.md, workledgers, or tracker state without explicit instruction.

## Requirement governance

`REQUIREMENTS.md` is the requirement authority for this repository and is checked with `redgate`. Before implementation work, read the applicable requirement row; if none covers the durable behavior, update `REQUIREMENTS.md` first or stop and ask for authority. When adding or changing rows, choose the ring by product foundation, not implementation size: lower rings capture stable kernel obligations and core contracts; higher rings compose on lower-ring obligations and must not weaken, redefine, or bypass them. If one row mixes foundational and optional behavior, split it before implementation. If the change alters durable product obligations, acceptance behavior, safety/recovery behavior, public interfaces, or verification duties, update `REQUIREMENTS.md` in the same slice and run the relevant `redgate` checks.

For behavior intended to stick, write or update a failing BDD/TDD test, contract test, or executable proof before implementation code; run it and record the RED result. Implement only after the requirement row and RED proof exist. If RED proof would be fake, unsafe, or disproportionate, state that exception before implementation and use the strongest cheaper check. Before final handoff, compare the user request and actual diff against `REQUIREMENTS.md`. If there is no requirement impact, the handoff must include exactly `REQUIREMENT IMPACT: none - <specific reason>`. If code, tests, or docs changed but `REQUIREMENTS.md` did not, explicitly justify why no requirement row changed.

## Single-file agent-facing tool

`lines.zig` is a single-file, read-only inspection primitive for agents and humans. Keep stdout to selected file content only; send usage and diagnostics to stderr. Do not add regexes, embedded languages, shell evaluation, network access, deletion, hidden writes, prompts, colors, pagers, config discovery, or output formatting modes. Prefer POSIX `sh` smoke coverage in `smoke.sh` for the CLI contract; keep any broader workflow outside the tool.

## Verification

Run `zig build test` for the CLI smoke and `redgate lint --strict && redgate health --strict` for requirement-shape and citation checks before handoff.