…lete the pin (anthropics/claude-code#76606)

When CC migrates a hook reminder out of its tool_result into a standalone
system message mid-history, the pin restores the first-seen inline form —
but the migrated copy still forwarded, splicing the same content in twice
(measured live: ~61 kB splice, 124k tokens re-billed on one turn). Now a
standalone message whose wrapper-normalized bytes equal a live pinned
block is suppressed: never forwarded, never given a canonical identity.
Genuine changes (normalized bytes differ) still forward and reset per the
existing rule; assistant-role messages are excluded on principle.
Suppression is re-detected each request from the pin set — no new state
file. One event line per suppression rides the insertion event log.

The real-pair red-green check in the new test file needs the replay
tooling and capture; in this slice it skips, and runs where the tools
land (cnighswonger#276).

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01TZxGrF1LRBvmb7cFXmS2DH

…ture (slice of fork 2dfe0f0)

Path-scoped slice of fork commit 2dfe0f0: only the
insertion-suppression real-pair test and the pinned fixture it falls
back to. The same commit's harvest-pin.test.mjs and
mitigation-output-form.test.mjs changes belong to the verification-tools
slice (cnighswonger#276) and are not part of this PR.

Co-Authored-By: Claude opus-5 <noreply@anthropic.com>

…pinned blocks — the 587k's shape

CC sometimes migrates ALL of a message's volatile blocks out together,
joined into one standalone message (both hook reminders, wrapper-stripped,
joined with "\n\n"), rather than one standalone per block. The existing
single-block suppression set could never match that shape. Each pinned
entry with >=2 volatile blocks now also registers a join-hash — its
blocks' unwrapped texts, in wire order, joined with the one observed
separator — and findSuppressibleDuplicate checks it as a second pass.
No subset-merges, no speculative separators: only the one shape measured
live (capture s-633915a8, msg863/864, and independently confirmed on a
second real occurrence at msg640/641 the same session).

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
(cherry picked from commit 78940a0)

…cate is payload (insertion slice of fork e0f8fcb)

Path-scoped slice of fork commit e0f8fcb: the insertion-normalization
tail guard and its tests. The same commit's output-guard
assistant-terminal invariant (proxy/extensions/output-guard.mjs,
test/output-guard.test.mjs) belongs to the output-guard slice (cnighswonger#278) and
is not part of this PR.

Co-Authored-By: Claude opus-5 <noreply@anthropic.com>

… fork da9bf8c

Makes the file slice-portable: without tools/ the real-pair check now
reaches its designed skip instead of dying at module load.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01TcivCe2iLnKZxpB4qTXzEb

…test reads (fork b1f7c58)

The merge-suppression test does a top-level read of this harvested,
sanitized fixture (16KB, no addresses); without it the file dies at
load. The fork-only exclusion list names only LEDGER-*.json — this
fixture is public on the fork and rides with its test.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01TcivCe2iLnKZxpB4qTXzEb

…entity

messages-cache-breakpoint pinned index 0 against head mutation
(CC#47098). insertion-normalization recognises a message across
re-serializations by content identity instead of pinning its position,
which covers that rationale without spending the 4th breakpoint slot —
CC occupies three of the API's four; this extension took the last.

Holding that slot is not free even when the extension behaves: any
future consumer of the 4th breakpoint silently starves, and on our
fork the starvation MASKED a defective mid-history rung scheme for a
full day — removing the breakpoint first, in isolation, armed it
(measured: 57 self-inflicted stability violations before the scheme
itself was retired). Hence one rule this removal carries: retire any
breakpoint-dependent scheme BEFORE freeing the slot.

Measured after removal on two full-session corpora, replaying the real
pipeline: 0 stability, 0 safety, 0 sequence violations; the 4th slot
stays deliberately empty. A stale reference comment in the ttl-tier
pipeline test goes with it.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>