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 wan-huiyan/agent-traffic-control --skill session-handoff-number-collision-with-unmerged-siblinggit clone --depth 1 https://github.com/wan-huiyan/agent-traffic-controlWrote 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/wan-huiyan/agent-traffic-control/session-handoff-number-collision-with-unmerged-sibling)<a href="https://agentmods.dev/skills/wan-huiyan/agent-traffic-control/session-handoff-number-collision-with-unmerged-sibling"><img src="https://agentmods.dev/badge/skills/wan-huiyan/agent-traffic-control/session-handoff-number-collision-with-unmerged-sibling/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/wan-huiyan/agent-traffic-control/session-handoff-number-collision-with-unmerged-sibling"><img src="https://agentmods.dev/badge/skills/wan-huiyan/agent-traffic-control/session-handoff-number-collision-with-unmerged-sibling.svg" alt="Reviewed on agentmods" width="80" height="20"></a>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 | $0.00475 | $0.04317 |
| Opus 5.5 | $0.00190 | $0.01727 |
| Sonnet 5.5 | $0.00095 | $0.00863 |
| Haiku 4.5 | $0.00047 | $0.00432 |
Grade A, and why
session-handoff-number-collision-with-unmerged-sibling 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 — 228 lines — stays where its author put it; the contents beside it link to each section on GitHub.
Session-Handoff Number Collision With Unmerged Sibling
Problem
session-handoff Phase 1 Step 2 says "Write handoff doc → docs/handoffs/session_N_handoff.md." The implicit assumption is that you can determine N by inspecting docs/handoffs/ on the current branch. This assumption breaks when a parallel/sibling session ran concurrently in another worktree and its handoff PR hasn't merged into main yet.
Concrete sequence:
- Sibling session ran 2 hours ago in
.claude/worktrees/other/, draftedsession_167_handoff.md, opened PR #690 (still under review). - Sibling session updated MEMORY.md "Recent sessions" with an S167 entry AND appended to sessions_archive.md.
- You fork your worktree off
origin/main— MEMORY.md is local-user-state so you see the sibling's S167 entry, butdocs/handoffs/onorigin/maindoes NOT yet havesession_167_handoff.md(PR pending). - You run
ls docs/handoffs/→ highest is S166b → you pick S167. - You write
docs/handoffs/session_167_handoff.md+session_168_prompt.md. - Both sessions now claim S167. Disk doesn't conflict (different branches). MEMORY.md shows two S167 entries. Future readers can't tell which is canonical.
The collision is silent because:
lsonly sees the current branch's files.git log origin/main -- docs/handoffs/session_167_handoff.mdreturns empty (PR pending).- Pre-commit hooks don't check session-number uniqueness.
- The session-handoff skill itself doesn't tell you to cross-check MEMORY.md.
Context / Trigger Conditions
Activate this check during session-handoff Phase 1 Step 2 (before writing the handoff doc), or during Phase 4 Step 22.a (review-agent factual-accuracy pass), whenever all of:
- You've picked a session number N based on
ls docs/handoffs/. - There's a project-level MEMORY.md or sessions_archive.md that tracks recent sessions.
- The repo is in a "dense parallel-PR" state (multiple worktrees, multiple open handoff PRs in recent days, or a
pr-conflict-from-mid-flight-merges-style skill in the project's skill set).
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 First seen · 228 lines · 475 tokens per session scan A 254a4b55df71
session-handoff-number-collision-with-unmerged-sibling is a skill published in the GitHub repository wan-huiyan/agent-traffic-control (3 stars, last pushed 1mo ago), licensed MIT. It adds 475 tokens to every session and 4,317 once invoked, about $0.0019 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.
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