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.
npx agentmods add skills/fiveonecode/agent-skills/lifecycle-and-side-effects-correctnessnpx skills add fiveonecode/agent-skills --skill lifecycle-and-side-effects-correctnessgit clone --depth 1 https://github.com/fiveonecode/agent-skillsWhat 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.
| Model | Per session | Once invoked |
|---|---|---|
| Fable 5 | $0.00088 | $0.00872 |
| Opus 5 | $0.00044 | $0.00436 |
| Sonnet 5 | $0.00018 | $0.00174 |
| Haiku 4.5 | $0.00009 | $0.00087 |
Grade A, and why
lifecycle-and-side-effects-correctness 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.
How it starts
The opening of the file, as written. The whole thing — 78 lines — stays where its author put it; the contents beside it link to each section on GitHub.
Lifecycle And Side Effects Correctness
Overview
Use this skill to prevent duplicate, stale, missing, or misattributed side effects across lifecycle transitions. Treat analytics, purchases, network retries, persistence, and callbacks as contract-bearing effects, not incidental code inside a view or async closure.
Workflow
1. Identify the owner
- Name the durable owner for each effect: service, coordinator, store, view model, view task, or external SDK.
- Keep one-shot effects out of view identity when remounts,
.id(...), previews, or sheet recreation can run the code again. - Separate view-local state from session, purchase, analytics, or persisted state.
2. Map lifecycle transitions
List the transitions that can start, repeat, cancel, or complete work:
- appear, disappear, dismiss, remount, reload, retry, background, foreground;
- task start, cancellation, timeout, success, failure, fallback;
- purchase start, product/offering reload, checkout, restore, completion;
- analytics impression, dismiss, branch, conversion, error, and retry.
For each transition, write the expected state and allowed side effects.
3. Enforce side-effect invariants
- No duplicate side effects from view remount,
.taskrestart,.onAppear,.id(...), or sheet recreation. - No stale completion side effects after cancellation, dismissal, navigation away, or superseded input.
- No false dismiss/present, impression, purchase, or retry analytics caused by view identity churn.
- In-flight purchase or mutation actions are idempotent, disabled, or otherwise guarded.
- Retry paths emit required lifecycle events exactly as specified and preserve session attribution.
- Failure paths either emit the required failure effect or explicitly suppress it under a documented rule.
- Persisted state, analytics properties, and user-visible copy derive from the same canonical source when they describe the same decision.
4. Check identity and attribution
- Define the stable session, impression, request, purchase, or operation ID before work starts.
- Preserve attribution through retries, slow loads, fallback, and personalized copy refresh.
- Do not derive experiment, package, offering, campaign, or branch attribution from display text when a canonical ID exists.
- Normalize stale IDs only at the boundary that owns the crosswalk; do not let tests erase identity bugs through broad normalization.
What ships with it
1 file beside SKILL.md in the same directory: the scripts, references and assets a skill reads on demand. Not counted in the per-session cost; read them before you install if any of them is executable.
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.
- 3d ago First seen · 78 lines · 88 tokens per session scan A 5f8dd0b3712e
lifecycle-and-side-effects-correctness is a skill published in the GitHub repository fiveonecode/agent-skills (19 stars, last pushed 11d ago), licensed MIT. It adds 88 tokens to every session and 872 once invoked, about $0.0004 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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