assert-log-story

A testing rule for proving that important application events appear in captured logs with the expected context, wording fragments, and severity.

In plain words
What is it for?
Use it to write pytest log-capture tests for successful and rejected paths, check declared log-story steps, and ensure tests never expose secrets in logs.
Why use it?
It prevents a feature from being marked complete merely because logging statements exist or a log file was inspected manually.

Cursor rule for Cursor

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 rules/featurefactory-io/mimir/assert-log-story
Clone the repo
git clone --depth 1 https://github.com/FeatureFactory-io/mimir

Made for: Cursor.

Per session 332 This file is loaded in full into every session.
When invoked 332 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 $0.00332 $0.00332
Opus 5 $0.00166 $0.00166
Sonnet 5 $0.00066 $0.00066
Haiku 4.5 $0.00033 $0.00033

Measured 2d ago against content hash 8972fb91307a, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

assert-log-story 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 2d 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.

.cursor/playbooks/Edda/rules/assert-log-story.mdc · 22 lines

What it actually says

Mimir metadata: slug do-assert-log-story; always_apply: false (link to BPE-02 / MIN-04 / TFK-02).

When a plan or iteration manifest declares a Log Story Script (or log_story_script[] / log_tests[]), you MUST prove those beats with pytest caplog (or equivalent log capture) — not by grepping logs/app.log alone, and not by “logging statements exist” checklists.

Requirements

  1. For each Log Story Script row, a test asserts the where + beat + must_include fragments appear in captured logs at the declared level (default INFO; WARNING/ERROR when the script says so).
  2. Cover happy and reject paths when the scenario has both (test_*_log_story_happy / test_*_log_story_reject).
  3. Use the shared helper from skill Pytest Log Story Assertions (tests/support/log_story.pyassert_log_story(...)) once TFK-02 has bootstrapped it.
  4. Log-story tests ship in the same commit as behavior green — never a deferred logging slice.
  5. Never assert on raw secrets, tokens, or passwords in log lines.

Anti-patterns

  • Behavior test green while log story absent or weakened to logger.info("done")
  • Manual logs/app.log inspection as the only DoD for observability
  • Skipping checkpoint.log_story_command when the manifest lists log_tests
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. 2d ago First seen · 22 lines · 332 tokens per session scan A 8972fb91307a

Subscribe to this mod's changes

assert-log-story is a cursor rule published in the GitHub repository FeatureFactory-io/mimir (13 stars, last pushed 4d ago), licensed Apache-2.0. It adds 332 tokens to every session, about $0.0017 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.