ktg-plugin-marketplace/plugins/ultraplan-local/tests/fixtures/skill-factory/draft-accepted.md

name	description	layer	cc_feature	source	concept	last_verified	ngram_overlap_score	review_status
session-startup-hook-pattern	Pattern for warming up agent context at conversation boot	pattern	hooks	./source-accepted.md	warm-start briefing via boot hook	2026-04-18	null	pending

Use this when

You want each new conversation to begin with the agent already aware of project status — pending tasks, recent commits, key file paths — instead of burning early turns on orientation.

Shape

Bind one script to the boot lifecycle event. Inside, gather whatever situational data justifies opening a fresh chat with: git log summary, todo file digest, branch identity, env snapshot. Format as terse markdown headings. Emit on stdout. The runtime grafts whatever you print into the model's opening context window.

Forces

Cold turns cost real seconds. Anything you compute inside this script delays the first user prompt visibly. Therefore: prefer cached lookups, avoid synchronous calls to remote services, and timebox expensive operations. If a piece of data takes longer than roughly 200 ms to fetch, demote it from the briefing or front-load a cache refresh asynchronously elsewhere.

Multiple installation layers can each register their own boot script. They run in this order: marketplace-supplied first, your personal home-level second, and project-rooted third. Outputs concatenate without merging. Two scripts both reporting the branch name will both show up. There is no built-in dedupe.

Crash semantics are partial-write friendly: anything you streamed to stdout before exiting non-zero still reaches the agent. The fix is to assemble the full briefing in a buffer and only flush on the success path. That way a midpoint failure leaves an empty intro rather than a torn one.

Gotchas

• No native simulator. Test by piping a hand-crafted payload directly into the script and reading the stdout it returns. Keep one canonical payload checked in.
• No selective firing — boot scripts cannot be scoped to subdirectories or file patterns. Workaround: branch inside the script body and short-circuit early when the heuristic does not match.
• Privileges are unfiltered: these scripts run with full operator credentials before any agent sandbox spins up. Audit third-party scripts before enabling them, and pin their versions to defeat silent updates.
• Telemetry is your problem: the runtime does not emit structured execution logs. If you want metrics, append to a local jsonl yourself from inside the script.

Anti-patterns

• Doing remote network calls on the hot path without caching.
• Skipping output buffering and streaming partial briefings.
• Allowing two layers to print conflicting information without coordinating.
• Trusting installed marketplace scripts implicitly.

Decision quick-check

Pick this approach when:

• Pending state across sessions is non-trivial enough to merit the boot delay.
• You can keep the script under a 250 ms wall-clock budget.
• The information surfaced changes meaningfully between sessions.

Skip it when:

• Project state rarely shifts; static instructions in CLAUDE.md serve the same purpose at zero startup cost.
• The data you would print is sensitive and could leak into copies of the conversation transcript.
• You are still iterating on what should appear; build the briefing as a plain script the operator runs manually before nailing it down as a boot binding.