Apply when context is filling up: large outputs, long files, repeated reads, fan-out planning. Route bulk to subagents; keep summaries in the main thread, not raw payloads.
Collected from public GitHub. Every version is saved exactly as it was and never changes. Install it at an exact version with the mdr tool, and every file is checked before it reaches your agent. The main file is checked against the SHA-256 fingerprint recorded here, and the others against the fingerprints GitHub keeps for its source commit. The automatic checks below grade the latest version, and the same checks always give the same file the same grade.
What the file says
# Guard the Context Window
The context window is finite and non-renewable within a session. Every token that enters should earn its place.
**Why:** Context overflow degrades reasoning quality, creates compression artifacts, and halts progress. Unlike compute or time, context spent inside a session cannot be reclaimed.
**Pattern:**
- **Isolate large payloads.** Route verbose outputs, screenshots, and large documents to subagents. The main context gets summaries, not raw data.
- **Don't read what you won't use.** Read selectively based on relevance. If a file isn't needed for the current task, skip it.
- **Keep frequently used content inline.** Templates and references used on every invocation belong in the skill file, not in separate files that cost a read each time.
- **Size phases and cap scope.** Limit files per phase, set turn budgets, account for mechanism costs.
The line at the top of this page pins the label git:20260827.04830a9, which is what most people want. This one pins the sha256 fingerprint of the contents instead, so it survives a label being moved. Either way the exact version is written to mdr.lock, and mdr install downloads and checks those contents again, so it installs them exactly or stops with an error.
GET https://markdownregistry.com/api/v1/artifacts/art_aaizxtwgvijmkek7
GET https://markdownregistry.com/api/v1/resolve?ref=painhardcore/pstack/principle-guard-the-context-window
GET https://markdownregistry.com/api/v1/blob/17301d7bd38c98b4ea73d9390a4565c5623b06f454a71b568adb64589653f396
Your AI assistant does the legwork. You hear about the deals worth your word. Hand yours the standing instructions at modelranch.com and it joins the network that reads files like this one.
painhardcore/pstack · .opencode/skills/architect/SKILL.md · Sketch types, signatures, and module structure before code, then stay in the loop while implementation fills in. Use…
painhardcore/pstack · .opencode/skills/arena/SKILL.md · Spawn N parallel candidates at the same task, pick a base, graft the strongest parts of the losers into it. Use for…
painhardcore/pstack · .opencode/skills/blast-radius/SKILL.md · Find what a change could break somewhere else before it ships, beyond the diff, and prove the one fact it's safe…
painhardcore/pstack · .opencode/skills/create-verification-skill/SKILL.md · Generate a project-local verification skill that drives your app the way a user does — any language, framework, or…
painhardcore/pstack · .opencode/skills/figure-it-out/SKILL.md · Design an auditable playbook when no narrower one fits: a large migration, an ambitious multi-part change, or work a…
painhardcore/pstack · .opencode/skills/how/SKILL.md · Explain how a subsystem works, trace a runtime flow, or determine where code and ownership belong before making a…
painhardcore/pstack · .opencode/skills/interrogate/SKILL.md · Use for "interrogate", "adversarial review", "multi-model review", "challenge this", "stress test this code", "find…
painhardcore/pstack · .opencode/skills/principle-boundary-discipline/SKILL.md · Apply when wiring validation, error handling, or framework adapters. Concentrate guards at system boundaries (CLI…
cursor/plugins · harness/pstack/claude-code/skills/principle-guard-the-context-window/SKILL.md · Apply when context is filling up: large outputs, long files, repeated reads, fan-out planning. Route bulk to subagents…
cursor/plugins · pstack/skills/principle-guard-the-context-window/SKILL.md · Apply when context is filling up: large outputs, long files, repeated reads, fan-out planning. Route bulk to subagents…
michael-denyer/pstack-claude · plugins/pstack/skills/principle-guard-the-context-window/SKILL.md · Apply when context is filling up: large outputs, long files, repeated reads, fan-out planning. Route bulk to subagents…
backnotprop/pstack · skills/principle-guard-the-context-window/SKILL.md · Apply when context is filling up: large outputs, long files, repeated reads, fan-out planning. Route bulk to subagents…
j-star-films-studios/vibecode-protocol-suite · assets/.agent/skills/engineering-principles/guard-the-context-window/SKILL.md · Apply when context is filling up: large outputs, long files, repeated reads, fan-out planning. Route bulk to subagents…
creedants/pstack-t3 · skills/principle-guard-the-context-window/SKILL.md · Apply when context is filling up: large outputs, long files, repeated reads, fan-out planning. Route bulk to subagents…
arjitj2/open-pstack · plugins/pstack/skills/principle-guard-the-context-window/SKILL.md · Apply when context is filling up: large outputs, long files, repeated reads, fan-out planning. Route bulk to subagents…
edbertchan/catstack · corpus/skills/principle-guard-the-context-window/SKILL.md · Apply when context is filling up: large outputs, long files, repeated reads, fan-out planning. Route bulk to subagents…
