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/xyruscode/ai-sync/context-rot-preventionnpx skills add XyrusCode/ai-sync --skill context-rot-preventiongit clone --depth 1 https://github.com/XyrusCode/ai-syncWhat 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 | $0.00083 | $0.00667 |
| Opus 5 | $0.00042 | $0.00333 |
| Sonnet 5 | $0.00017 | $0.00133 |
| Haiku 4.5 | $0.00008 | $0.00067 |
Grade A, and why
context-rot-prevention 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.
How it starts
The opening of the file, as written. The whole thing — 31 lines — stays where its author put it; the contents beside it link to each section on GitHub.
Context Rot Prevention
Prevents context rot: hands a session that has grown heavy off to a fresh, nested context (auto-spawn when the tool allows it, otherwise a self-contained handoff prompt) before output quality drops. Full procedure, rationale, and the handoff template live in docs/context-rot.md.
When to use
- A session has many turns, many distinct files read or edited, or keeps re-reading files it already loaded.
- You catch yourself re-deriving state you already settled earlier in the conversation.
- Token-usage telemetry (where the tool exposes it) shows the context window is near the cap.
- The user asks to split, continue in a fresh session, or hand the thread off.
- A slice of work is done and the next slice is better done with a clean context.
Don't use for
- Short or one-shot tasks that will finish in the current context. Splitting is overhead.
- Near-complete work. A handoff costs more than seeing it through.
- Parallel fan-out of subtasks into many agents. That is
workflow-orchestration.md/ the Workflow tool, not a continuity handoff.
Decision
- Assess the envelope. Weight the cumulative signals (turns, working-set size, re-deriving state, telemetry if present). No single number decides; read the shape.
- Checkpoint. Commit or otherwise leave the tree in a known state; write a memory note for non-obvious decisions.
- Split: use a native nested-session primitive when available and safe. This Copilot app:
create_session/send_session_message. Claude Code:claude --continueor a typed subagent. Codex:codex resume. Cross-CLI read-only fan-out:agent orchestrator. - Else: emit a self-contained handoff prompt. Write it so a fresh session with zero prior context can continue immediately, and tell the user where it goes. Use the template in the doc.
The handoff prompt must carry: goal, done-so-far, current state (branch, HEAD, key files), decisions already made, exact next step, and where to re-derive context.
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.
- 2d ago First seen · 31 lines · 83 tokens per session scan A 7313a2e1b203
context-rot-prevention is a skill published in the GitHub repository XyrusCode/ai-sync (2 stars, last pushed 2d ago), licensed MIT. It adds 83 tokens to every session and 667 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 2026-08-31.
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