daily-fix: exclude /tmp scratch from ruff format hook

Overview / Motivation

Auto-filed by /daily 2026-07-22 (transcript sweep). The PostToolUse ruff format hook rewrites freshly-Written /tmp/*.py scratch scripts, invalidating the harness's "file state is current in your context" assumption: in #1602 (abee1289, 17:41:29Z) an Edit on a just-Written /tmp edit script failed "String to replace not found" because the formatter had reshaped the file between the Write and the Edit — one extra Read+Edit round.

Goal

The PostToolUse ruff-format hook in .claude/settings.json skips /tmp/ paths (scratch scripts are ephemeral; formatting them buys nothing and breaks Edit anchors).

Workflow gap

• Bug observed: abee1289 (#1602), 17:41:29Z Edit failure → 17:41:37Z "The formatter hook reshaped the file — reading the R11a region to get the current form."
• Why it is a workflow gap: the hook matcher formats every .py regardless of location; /tmp scratch is written to be executed once, and the reshape races the writer's in-context file state.
• Confidence: high.
• verified-at-filing: .claude/settings.json PostToolUse hook (line ~162) read at filing: if [ -n "$file_path" ] && echo "$file_path" | grep -qE '\.py$' — no path exclusion (presence claim, binds), 2026-07-23 UTC.

Proposed change (refine in planning)

Add a /tmp/ (and /dev/shm/) exclusion to the hook's path test, e.g. grep -qE '\.py$' → also ! echo "$file_path" | grep -qE '^/(tmp|dev/shm)/'.

Scope / surfaces

• Primary target: .claude/settings.json (PostToolUse ruff hook command).

Constraints / invariants

• Repo-tree formatting behavior unchanged. Recursion guard applies.

Provenance

• fingerprint: f362848c4a14

• workflow_fix_target: .claude/settings.json