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 skills add restarter/lets-workflow --skill session-boundarygit clone --depth 1 https://github.com/restarter/lets-workflowWrote this? Show the measurements
A badge with what this costs and how it scanned, read live from this page, so it follows the numbers instead of freezing them. Markdown for a README, HTML for a documentation site or a project page.
[](https://agentmods.dev/skills/restarter/lets-workflow/session-boundary)<a href="https://agentmods.dev/skills/restarter/lets-workflow/session-boundary"><img src="https://agentmods.dev/badge/skills/restarter/lets-workflow/session-boundary/github.svg" alt="Measured on agentmods" height="20"></a>Or the 80×15 button, for a site that already has a row of RSS and ATOM ones. Only the verdict fits; the numbers stay here.
<a href="https://agentmods.dev/skills/restarter/lets-workflow/session-boundary"><img src="https://agentmods.dev/badge/skills/restarter/lets-workflow/session-boundary.svg" alt="Reviewed on agentmods" width="80" height="20"></a>- NVIDIA SkillSpector pass
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.
| Model | Per session | Once invoked |
|---|---|---|
| Fable 5.1 | $0.00055 | $0.02412 |
| Opus 5.5 | $0.00022 | $0.00965 |
| Sonnet 5.5 | $0.00011 | $0.00482 |
| Haiku 4.5 | $0.00006 | $0.00241 |
Grade A, and why
session-boundary 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 1mo 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 — 149 lines — stays where its author put it; the contents beside it link to each section on GitHub.
Session Boundary
Resolve the ref a session's commit range is measured from, validate it, and say how far it can be trusted. /lets:end needs it EARLY (it gates which settlements are offered) and session-snapshot needs it LATE (the ### Range block it writes into a durable file). Two copies of a validation ladder drift, and drift here is what produced a confident "260 commits" for a 6-commit session (lets-370mx), so the ladder lives here and nowhere else.
Contract: no args. Output: four echoed lines the caller reads VERBATIM.
SESSION_BOUNDARY=<sha | none>
SESSION_TRUST=<exact | prior-session | estimate | none>
SESSION_COMMITS=<N | unknown>
SESSION_RANGE_DESC=<one-line human description, always carrying the trust level>
Diagnostic NOTEs go to stderr - surface them to the user, they are the loud half of every degradation.
Fail closed. If the four lines do not arrive, the caller MUST assume SESSION_TRUST=none / SESSION_COMMITS=unknown and proceed as though no boundary exists. Never re-derive one inline - a second copy is a second answer, which is the defect this skill exists to prevent.
Trust levels
| level | boundary | what the caller may claim |
|---|---|---|
exact |
this session's session: line in .task-<branch-slug> |
the count is this session's work |
prior-session |
a session: line or legacy slugged ref recorded by an EARLIER session |
a real recorded boundary, but not this session's - best-effort |
estimate |
nothing recorded; derived from this branch's point off $LETS_MERGE_BRANCH |
what this BRANCH added, not what this session did |
none |
nothing usable (rejected, or absent while HEAD is $LETS_MERGE_BRANCH) |
nothing - there is no number |
A caller that gates a destructive or task-completing offer on the range must require exact or prior-session. SESSION_RANGE_DESC always embeds the level, so a number cannot travel into a file or a tracker comment without the qualifier that earned it.
Resolve
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.
- 1mo ago Changed · +2 lines ca217d72a061
- 1mo ago First seen · 147 lines · 55 tokens per session scan A 5b4d982ec237
session-boundary is a skill published in the GitHub repository restarter/lets-workflow (17 stars, last pushed yesterday), licensed MIT. It adds 55 tokens to every session and 2,412 once invoked, about $0.0002 per session on Opus 5.5. 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 2026-09-05.
Other skills, from other repositories
fix
Read this repo's open issues, triage them, and open one pull request per issue that can be fixed without a judgement call. Issues that need a decision, or that look stale or superseded, are reported with a recommendation rather than guessed at.
watch-pr
Watch a GitHub pull request for CI status, reviews, comments, merge conflicts, and terminal states using the gh-watch extension. Use when the user wants to monitor a PR, wait for CI, or track PR progress.
diff-summary
Structured triage of a git diff. One call replaces the per-file Read sweep an agent normally does to figure out which files in a diff are tests, which touch the public API, which are migrations, which need careful review.
gh-find-prs
Survey open Codewhale PRs and triage each for mergeability and disposition against the real landing branch.
git
Git and code hosting platform management — GitHub, GitLab, Codeberg, Forgejo. Zero barrier — install x-cmd and manage repos from the terminal. Use for "git", "github", "gitlab", "repo", "pull request", "code hosting".
pr-threads-address
Address PR review feedback by systematically working through every unresolved PR review thread on the current branch's PR - analyze each comment, make the requested code changes (with tests where useful), commit, and optionally reply and resolve.