[friel-openai]

Summary

• Add the existing RolloutReferenceItem wire format and immutable SegmentId reader support.
• Separate bounded model replay from fallible complete-history reconstruction.
• Read predecessor segments in thread listing, app-server transcript APIs, memory extraction, and feedback attachments.
• Reject legacy references when resolving them would substitute a newer live segment.

Context

This is the reader prerequisite split from #27249 after review identified persistence and rotation concerns in that PR. Existing Frodex rollouts already contain rollout_reference and legacy fork_reference items, so decoding and read compatibility are useful independently of enabling Session segmentation.

This PR does not declare the Session segmentation feature and has no production RolloutReferenceItem constructor. It does not add a database migration. The serialized fields, defaults, and fork_reference alias are unchanged from #27249 at ffbd02abb5.

Read contracts

• segment_id is authoritative. Resolution validates the target file's SessionMeta.segment_id and does not fall back to a same-named live file with different content.
• A path-only legacy reference checks the plain or compressed archived predecessor before the mutable live path. A segment-identified live successor is rejected rather than spliced into history.
• Model replay applies the reference depth budget. Complete transcript consumers ignore that model budget, detect cycles, and return an error instead of silently dropping an unreadable predecessor.
• Thread search attributes segment predecessors to the current thread. Prefix-truncated fork history remains searchable through its source thread, avoiding duplicate child results.

The feature flag, per-thread writer transaction, atomic canonical-file replacement, immutable reference publication, and reachability-based deletion belong to writer follow-up #27249.

Test plan

• RUST_MIN_STACK=8388608 cargo test -p codex-rollout (85 passed)
• RUST_MIN_STACK=8388608 cargo test -p codex-thread-store (80 passed)
• RUST_MIN_STACK=8388608 cargo test -p codex-app-server-protocol (228 unit and 2 schema fixture tests passed)
• RUST_MIN_STACK=8388608 cargo test -p codex-memories-write (36 passed)
• RUST_MIN_STACK=8388608 cargo test -p codex-app-server --lib (248 passed)
• RUST_MIN_STACK=8388608 cargo test -p codex-core thread_rollout_truncation::tests (20 passed)
• Focused disabled-feature thread/resume, unloaded thread/read, feedback attachment, interrupted-fork, and identity-validation fixture tests passed
• Scoped just fix for the six changed crates
• Argument-comment lint passed for 547 normal and 127 manual Bazel targets

[chatgpt-codex-connector]

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[github-actions]

Closing this pull request because it has had no updates for more than 14 days. If you plan to continue working on it, feel free to reopen or open a new PR.