check-cache-bugs

# Check Cache Bugs (CC#40524) Audit your Claude Code setup for cache and cost bugs discovered in March-April 2026. **Time**: ~30 seconds | **Scope**: version, config files, CLAUDE.md, skills, hooks, shell profiles, all claude binaries > **Note on cache contamination**: This skill loads content containing `cch=` strings into the current session's message array. For cleanest results, run this command at the very start of a fresh session, or via `claude -p "$(cat .claude/commands/check-cache-bugs.md)"` as a one-shot print-mode invocation. **Reference**: `anthropics/claude-code#40524` | **Discovered by**: `@jmarianski` + `@whiletrue0x` | **Extended by**: `@ArkNill` (ArkNill/claude-code-cache-analysis, April 2026) --- ## Background ### Fix Status (current as of v2.1.92) | Bug | Versions affected | Status | |-----|------------------|--------| | Bug 1: cch sentinel (standalone binary) | v2.1.36-v2.1.90 | **FIXED in v2.1.91** | | Bug 2: deferred_tools_delta on --resume | v2.1.69-v2.1.89 | **FIXED in v2.1.90** | | Bug 3: attribution header per-session hash | v2.1.69+ | **Active** (env var workaround) | | B4: Microcompact / silent context stripping | all versions through v2.1.92 | **Active** (GrowthBook controlled) | | B5: Tool result budget cap 200K | all versions through v2.1.92 | **Active** (MCP tools exempted) | ### Original three bugs (CC#40524) - **Bug 1** (FIXED v2.1.91): Bun's native HTTP layer did a same-length byte replacement of the `cch=00000` attestation placeh...