feat: nudge session-start toward on-demand skill search

[getappz]

Summary

Claude Code auto-lists every enabled skill's name+description on every session regardless of relevance, which compounds token cost as skill count grows. skill_search/skill_load (agentflare's MCP tools, verified working in dogfooding) already scan skill directories independent of Claude Code's own listing mechanism, making them a viable on-demand replacement for the always-on list — but nothing told the model to actually reach for them.

• Adds one line to session_start's output: nudge toward skill_search(query) then skill_load(name) before assuming a relevant skill doesn't exist.
• Extracted the message-building into session_start_message() (mirrors the _sync helper pattern already used in mcp_server.rs) so the nudge text has direct test coverage instead of only an indirect "doesn't panic" check.

Context on the "disable all skills" half of this

Claude Code's --disable-slash-commands flag suppresses the always-on skill listing while MCP tools (including skill_search/skill_load) stay fully functional — verified empirically:

claude --disable-slash-commands -p "list every tool you have access to"

shows no skill listing, but mcp__agentflare__* tools remain available. However, it's a launch-time CLI flag — no persistent settings.json key or environment variable equivalent was found, so making it the default for every session requires a shell-level wrapper/alias around the claude binary, which is outside this repo's scope to configure.

Test plan

• cargo build --workspace, cargo test --workspace (196 passed, +1 new)
• cargo clippy --workspace --all-targets — no new findings (pre-existing collapsible-if warnings elsewhere in hook.rs, unrelated to this diff)

Summary by CodeRabbit

• New Features
  • Updated the session-start guidance shown at launch with a new “skills load on demand” reminder, including references to skill search and loading commands.
• Bug Fixes
  • Improved how the session-start message is assembled so the displayed text is generated more consistently.

[coderabbitai]

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ℹ️ Recent review info

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📥 Commits

Reviewing files that changed from the base of the PR and between 6d0f4b6 and 57c9253.

📒 Files selected for processing (1)

• src/hook.rs

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📝 Walkthrough

Walkthrough

The session_start function in src/hook.rs was refactored to delegate message building to a new session_start_message function, which returns a string instead of printing directly. A new line prompting skill_search(query) and skill_load(name) usage was added, and tests were updated accordingly.

Changes

Session-start message refactor

Layer / File(s)	Summary
Extract message builder and add skill nudge src/hook.rs	session_start now delegates to session_start_message(agent), which returns the composed string (joined lines) including a new "Skills load on demand..." instruction referencing skill_search(query) and skill_load(name); tests updated and a new test added to verify this content.

Estimated code review effort: 1 (Trivial) | ~5 minutes

🚥 Pre-merge checks | ✅ 5

✅ Passed checks (5 passed)

Check name	Status	Explanation
Title check	✅ Passed	The title is concise and matches the main change: nudging session start toward on-demand skill search.
Description check	✅ Passed	The description covers the summary and test plan and includes extra context, but the reviewer notes section is not filled out.
Docstring Coverage	✅ Passed	No functions found in the changed files to evaluate docstring coverage. Skipping docstring coverage check.
Linked Issues check	✅ Passed	Check skipped because no linked issues were found for this pull request.
Out of Scope Changes check	✅ Passed	Check skipped because no linked issues were found for this pull request.

✨ Finishing Touches

📝 Generate docstrings

• Create stacked PR
• Commit on current branch

🧪 Generate unit tests (beta)

• Create PR with unit tests
• Commit unit tests in branch feat/skill-on-demand-nudge

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