CLAUDE.md cache not shared

“First prompts differ between sessions, so the context block is written to cache again on every start.”

Is this your bug? What gets counted gets fixed. Pile on.

Paste this into your agent. It files your report, with your error and version.

I hit this bug: rapsheet.dev/sheets/claude-code/issues/12847/file
Follow it to file my report. Show me the text before you send.

No install. No account. Public and anonymous. The link asks your agent for one report, nothing else. What it sends

Quiet. No reports and thumbs-up in the last two weeks, down from 2 a week at the late-October peak. Not fixed, but a workaround is known.

CLAUDE.md context never shared in prompt cache across sessions. The context block sits in messages[0] with the user's first prompt and has no cache_control breakpoint of its own.

Is this your bug?

File my report

Where: Prompt caching
Versions: 2.1.270 to 2.1.299
Platforms: macOS, Windows
How bad: Breaks a normal workflow.

Part of: Prompt cache misses and re-writes11 bugs

Interactive sessions get 5m cache TTL18 people
Sleep re-sends full agent context4 people
Warm prompt cache fully missed2 people
Resume re-writes prompt cache3 people
Cross-session prompt cache misses2 people
Prompt cache misses after system message3 people
Subagent prompt cache expires2 people
Background agent summary requests12 people
Context after prompt breaks cache4 people
Subagent resume cache miss4 people

Original reports3, newest first

Oct 21, 2026Prompt cache: CLAUDE.md context is rewritten on every session start because it shares messages[0] with the first prompt#104051
Oct 14, 2026Prompt cache: CLAUDE.md context is never shared across sessions because it shares a cache segment with the first user prompt#102042
Sep 14, 2026CLAUDE.md / auto-memory block is never shared across sessions: it sits in messages[0] after the system breakpoint, with no cache_control of its own#94417