Add critical instructions and hooks for Claude Code

[dapplion]

Summary

• Add CRITICAL section at top of CLAUDE.md to ensure Claude always runs formatting and linting after code changes
• Add .claude/settings.json with post-tool-call hook to remind about formatting and linting after Edit/Write operations

This helps ensure Claude Code consistently follows the project's code quality requirements.

Test plan

• Verify CLAUDE.md changes are visible
• Verify hook configuration is valid JSON

🤖 Generated with Claude Code

(Lion here)

Claude recognizes that it ignored Claude.md most of the time, and recommends this edits to actually lint and format when doing changes.

[michaelsproul]

I thought the plan was to add a commit hook that checks cargo fmt, so this is enforced by Git and not vibes

[dapplion]

I thought the plan was to add a commit hook that checks cargo fmt, so this is enforced by Git and not vibes

Do we want to have git hooks that apply to everyone?

[jimmygchen]

I don't think we need cargo check if we already run clippy

[jimmygchen]

I'm removing the cargo check command and merging this - please correct me if i wrong

[pawanjay176]

@dapplion I'm wondering why we can't have our own local versions of the settings.json. Why does this need to be committed for everyone?

[jking-aus]

@dapplion I'm wondering why we can't have our own local versions of the settings.json. Why does this need to be committed for everyone?

settings.json at project level is good for sharing hooks and tooling across the team. Your .claude/settings.local.json is not committed and overrides the project level settings

https://code.claude.com/docs/en/settings

[mergify]

Merge Queue Status

Rule: default

---

• ✅ Entered queue — 2026-02-18 02:53 UTC
• 🚫 Left the queue — 2026-02-18 02:54 UTC · at 1023d6fd54318c2b17a654fd7edbc19854ee4046

This pull request spent 42 seconds in the queue, with no time running CI.

Reason

The pull request #8715 has been manually updated

Hint

If you want to requeue this pull request, you can post a @mergifyio queue comment.

[jimmygchen]

LGTM, thanks!

[mergify]

Merge Queue Status

Rule: default

---

• ✅ Entered queue — 2026-02-18 02:55 UTC
• ✅ Checks passed · on draft merge queue: embarking unstable (2f7a1f3) and #8715 together #8848
• ✅ Merged — 2026-02-18 03:26 UTC · at d6069a46b5b81b4fcb9b952eca7c511357b49ccb

This pull request spent 31 minutes 2 seconds in the queue, including 29 minutes 18 seconds running CI.

Required conditions to merge

• check-success=local-testnet-success
• check-success=test-suite-success