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 GalaxyRuler/Galactic-skills --skill context-canarygit clone --depth 1 https://github.com/GalaxyRuler/Galactic-skillsWrote 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/galaxyruler/galactic-skills/context-canary)<a href="https://agentmods.dev/skills/galaxyruler/galactic-skills/context-canary"><img src="https://agentmods.dev/badge/skills/galaxyruler/galactic-skills/context-canary/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/galaxyruler/galactic-skills/context-canary"><img src="https://agentmods.dev/badge/skills/galaxyruler/galactic-skills/context-canary.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 | $0.00115 | $0.01421 |
| Opus 5.5 | $0.00046 | $0.00568 |
| Sonnet 5.5 | $0.00023 | $0.00284 |
| Haiku 4.5 | $0.00012 | $0.00142 |
Grade A, and why
context-canary 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 2mo 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.
This is a copy
98% identical to context-canary — 2 lines differ, which has more behind it and is treated as the original. This page carries a canonical link to it rather than competing with it.
How it starts
The opening of the file, as written. The whole thing — 65 lines — stays where its author put it; the contents beside it link to each section on GitHub.
Context Canary
A context canary is a trivially checkable standing instruction whose only job is to fail visibly. The classic form: "start every response with my name." The agent costs almost nothing to comply — so when the name disappears, that absence is data. The instruction didn't get harder; the agent's hold on its early-context instructions got weaker. Like the coal-mine canary, it dies first, before the failures you actually care about (forgotten constraints, ignored conventions, re-litigated decisions) start landing in your code.
This works because context degradation is silent and gradual. Models don't announce that they've stopped attending to instructions from 80k tokens ago, and compaction summaries quietly drop standing instructions. The canary converts an invisible failure into a binary, per-turn, zero-effort check. The research behind why this happens — context rot, lost-in-the-middle, instruction drift, compaction loss — is in references/research.md.
When to use this skill
- Installing a canary at the start of a long or high-stakes session.
- The user notices the canary stopped appearing and asks what happened.
- The agent itself realizes it can no longer find its canary contract in context.
- The user asks how trustworthy the current context still is.
The canary contract
When invoked, install the canary by stating the contract explicitly in one short message, then follow it. Default format — first line of every response from then on:
**Julius · t14 · ctx ok**
Three fields, each probing something different:
| Field | Example | What its failure means |
|---|---|---|
| Name | Julius |
The standing instruction itself fell out of effective context — adherence drift or compaction dropped it. |
| Turn counter | t14 |
Increment by 1 every response. A reset, skip, or repeat means continuity broke — almost always compaction or a summarization boundary. |
| Self-check | ctx ok / ctx aging / ctx thin |
The agent's honest estimate. aging: the session is long and early details are getting summarized in its own working sense of the task. thin: the agent is reconstructing earlier decisions instead of remembering them. |
What ships with it
3 files 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.
- 2mo ago First seen · 65 lines · 115 tokens per session scan A 42c8e8e7b7c2
context-canary is a skill published in the GitHub repository GalaxyRuler/Galactic-skills (5 stars, last pushed 2mo ago), licensed MIT. It adds 115 tokens to every session and 1,421 once invoked, about $0.0005 per session on Opus 5.5. A static security scan graded it A with 0 findings. It is 98% identical to context-canary, differing in 2 lines, and is treated as a copy.
context-canary compared with skills from other repositories
| Mod | Type | Stars | Last push | Licence | Scan | Tokens | Works with |
|---|---|---|---|---|---|---|---|
| context-canaryGalaxyRuler/Galactic-skills | Skill | 5 | 2mo ago | MIT | A | 115 | Codex |
| knowledge-ingestopenclaw/openclaw | Skill | 394k | today | MIT | A | 80 | Claude Code, Codex |
| mem0-oss-to-platformmem0ai/mem0 | Skill | 69k | yesterday | Apache-2.0 | A | 217 | Claude Code, Codex |
| forgetasgeirtj/system_prompts_leaks | Skill | 71k | yesterday | CC0-1.0 | A | 0 | Claude Code, Codex |
| Cortexdanielmiessler/LifeOS | Skill | 20k | 2d ago | MIT | A | 184 | Claude Code |
| memoryopensquilla/opensquilla | Skill | 7.1k | yesterday | Apache-2.0 | A | 44 | Claude Code, Codex |
| ha-data-storesshiwenwen/hope-agent | Skill | 1.9k | yesterday | MIT | A | 115 | Claude Code, Codex |