fix(compression): fence durable transcript revisions

[ruizanthony]

Summary

Fence compression against an atomic durable transcript revision instead of comparing a model-facing projection length with SQLite's active-row count.

This fixes the cross-repository race where WebUI can legitimately project fewer messages than the Agent's durable transcript, while a real concurrent mutation must still prevent stale compression output from publishing.

Root cause

len(durable_parent) > len(messages) was treated as evidence of concurrent writes. That is not a valid invariant across WebUI sanitization, deduplication, replay and sidecar projection. It caused false retries and could exhaust the provider context window. Conversely, without a durable revision/CAS boundary, a true concurrent rewrite could be missed between load and publication.

The previous PR head also introduced a separate CI regression: importing durable state through gateway.config -> gateway.session -> agent.turn_context -> agent.conversation_compression froze state.db before runtime HERMES_HOME resolution. The current head keeps those imports lazy; the existing runtime-home regression is green again.

Changes

• capture messages and their durable revision from the same SQLite rows;
• include active-row count, max active id, content digest and api_content sidecar digest;
• propagate revision state through TurnContext/TurnRunner and refresh it after clean Agent writes;
• re-check after acquiring the compression lease and at publication/mutator boundaries;
• fail closed on stale or unverifiable revisions without replaying tools;
• preserve current-turn partial output under explicit stale classification;
• retain opt-in durable row IDs and coherent rewind/rotation snapshots;
• keep durable-state imports lazy so runtime profile/home selection remains authoritative.

Dependency and pairing

• stacked dependency: fix(compression): recover live tip across rotation chains #71486 at 5d4539dcfc782953fbc27bd630b96b245c7c7621;
• this PR head: 1bdac5d4547914d70c134f06af0435568a35159c;
• rebased base: cb11a7e25579638c9f67e8501dd151f581c4c942;
• paired WebUI PR: fix(compression): fence WebUI with durable revisions nesquena/hermes-webui#6554 at 0f7c4cef3f38aab591ae6fa6fcfdb76a869c669a.

Merge #71486 first, then rebase this PR onto the resulting main to drop the stacked duplicate and revalidate the new exact head together with WebUI.

Validation

• critical Agent gate: 96 passed, 0 failed;
• exact cross-repo WebUI↔Agent gate: 54 passed, 0 failed;
• broader Agent matrix: 792 passed; 2 TUI config tests fail only because the local control environment lacks ruamel, reproduced identically on unmodified base (515 passed, same 2 failed);
• Ruff on changed lazy-import files, py_compile, and git diff --check: passed.

No deployment or merge is performed by this PR update.

[ruizanthony]

Rebased as a stacked follow-up on #71486, preserving both live-tip recovery and durable transcript revision fencing. Exact head: 57cfe13eb85ff7971c2b2fe6926ea50c4e2a813b. Combined targeted gate: 297 passed; diff check clean. Merge #71486 first, then this branch can be rebased once more onto upstream main to drop the stacked commit.

[teknium1]

Thanks for tracing this to the durable-row-count assumption. The premise is confirmed on current main: agent/conversation_compression.py:1725-1744 still adopts durable history when len(durable_parent) > len(messages), which is not a valid concurrency test for sanitized or deduplicated projections.

Problems

• The submitted branch is currently conflicting, and its base predates major changes to the affected state and gateway paths. Current hermes_state.py:6332-6386 includes the independent include_row_ids contract on get_messages_as_conversation, so the revision-aware load must be integrated without regressing that API surface.

Suggested changes

• Salvage the revision/CAS design into the current state and gateway flow, retaining the PR's projection-mismatch, sidecar-mutation, and stale-publication tests against the current interfaces.

Automated hermes-sweeper review.

[ruizanthony]

Rebased and repaired on current main. Exact review target: 1bdac5d4547914d70c134f06af0435568a35159c, stacked on #71486 exact head 5d4539dcfc782953fbc27bd630b96b245c7c7621. The prior CI failure is fixed by keeping durable-state imports lazy; 96/96 critical tests and 54/54 paired WebUI tests pass. Please review this exact SHA; after #71486 merges, this PR will be rebased once more and the paired gate rerun.

[ruizanthony]

Pairing metadata correction: the WebUI tree is unchanged, but its final commit was republished with the required verified author/committer identity. Exact paired review target is now WebUI 0f7c4cef3f38aab591ae6fa6fcfdb76a869c669a with this Agent head 1bdac5d4547914d70c134f06af0435568a35159c; the exact pair remains 54/54 green.