Regenerate only native V3 Session/output oracles through the shipped headless and SDK profiles. These outputs retain system-message admission before users, bind request metadata before title fallback, and record real V3 delivery acknowledgments. Historical V0/V1/V2 replay inputs remain unchanged; pinned scenarios keep separate writer outputs.
The upper headless/SDK refresh covered109 cases; the only initial failure used macOS system Python3.9 for the PTC Python scenario, which passed with the declared CPython3.14 PATH. No assertion or runtime behavior was changed to accommodate it.
Retained V0/V1 fixtures remain replay inputs while writer.expected JSONL records the actual current V3 output. Record these through the shipped headless scenarios rather than reverse-normalizing system messages back into historical headers. Preserve generation-qualified reference provenance, and correct the unreleased PowerShell seed to start its step and protected system head before user surface input.
Validation: the structural migration, real persistence, corpus and snapshot-support gate passed616 tests with one intentional skip; all91 headless refresh cases pass after the audited assistant-attempt source handling. Every predecessor path remains restored to the shared V3 base, and generated changes are confined to V3/output oracles and current tool schema pins.
Restore all 147 historical canonical fixtures changed by the lower branch to exact shared base 220ff708e3628a9be46d9747d09af6d8cd742f0d bytes (145 V2 and two V0). All 180 committed V0/V1/V2 canonical files now have zero diff against that base, including unchanged Python, test-support and preview sources.
Preserve corrected lower writer bodies in 146 V3 successors across 119 owner directories: replace 135 unreleased V3 counterparts and add 11 siblings. Change only each copied Session header version; preserve all body bytes, raw model streams, inline images, IDs, references and historical delivery generation markers. Remove two unshipped V2 additions after creating their V3 sibling: record-suite/rec-pin and empty-response-retry-current.
Keep six explicitly historical snapshot owners pinned with no V3 sibling. Restore the two pre-step V0 record child sources without synthesizing current output. Fix seven embedded Session header versions in exactly five test-support behavior owners whose output filenames already select V3. Leave protocol expectations, shared references, sidecars, consumer scripts and production migration/normalization code untouched.
Validation: purpose-built temporary Python inventory and verifier checked 337 canonical headers, 3714 successor JSON rows, message roles, contiguous child roles, exact successor bodies, all 180 historical base bytes and zero git diff, noncanonical JSONL immutability, six retained owners and six unchanged preview fixtures. git diff --cached --check passed. Temporary generators removed. Strict migration, native refresh and replay remain pending parent integration; unsupported pre-step sources are reported separately.
Carry the newly merged current-writer spill recording through the representation change on its owning PR. Add the system surface message and remove header.system, while retaining the representation layer title-before-request order and every captured spill/source fact. The dependent admission PR separately records its changed title scheduling.
Validation: JSON records parse; the same recorded scenario was refreshed through the built integrated loop. Only layer-specific title order differs, and both variants are replayed before publication.
Tianyi Cui