fix(hints): parse current Codex user-message event shapes in rollout renderer

[ScriptedAlchemy]

Evidence

A 12-hour hook-hint audit found six canonical user.text → hooks.additional_context pairs, but the renderer produced no submitted prompts:

• 334 model messages observed
• submitted_user_messages=0
• developer_trace_hints=0
• rendered_cases=0

The current Codex rollouts encode prompts as response_item user.text and event_msg.item_completed UserMessage. scripts/render-codex-hook-inputs.py recognizes only the older shape. The same legacy-only assumption appears in crates/tracedecay-sessions/src/runtime/hosts/codex.rs.

This makes hint evaluation falsely look like an empty corpus and prevents safe classifier tuning.

Expected behavior

Canonical current Codex user messages are recovered through the maintained session/redaction authority and paired with their hook context without fabricating or duplicating prompts.

Acceptance

• Add real-rollout fixtures for both current event shapes.
• Render the six known 12-hour prompt/context pairs from the bounded audit.
• Preserve legacy parsing and canonical redaction/content authority.
• Prove malformed, duplicate, and non-user events are rejected or ignored deterministically.
• Re-run the deterministic hook-hint evals and report scored positives/silence; do not tune classifiers from an empty-positive sample.

[ScriptedAlchemy]

Fix is complete and pushed on branch agent/issue-842-hook-renderer at b380727, based on current PR tip 250c5e0. The renderer now recognizes and deduplicates item_completed/UserMessage; the production Codex adapter indexes the same shape with stable item identity while preserving legacy input and skipping response_item duplicates. Evidence: Python regressions 3/3, Rust current-shape tests 2/2, hint evals 6/6, clippy/rustfmt/diff-check/commitlint clean. The real 12-hour render now recovers 430 submitted prompts and 121 hint cases instead of an empty corpus. Leaving open until the commit is integrated into #707.

[ScriptedAlchemy]

Fresh-floor implementation is complete and independently reviewed.

• Branch: agent/issue-842-hook-renderer-fresh
• Exact tip: 5bdd064
• Central floor merged: 27b2d3c
• Remote equality: confirmed; isolated worktree clean
• Independent exact-tip review: CLEAR, with no concrete blocker

Acceptance evidence at the merged tip:

• Codex hook renderer: 4/4
• Codex session units: cc-5377, 94/94
• Shared JSONL admission: cc-5381, 31/31, including the central identity-collision retry cases
• Production Codex admission/projection: cc-5382, 6/6
• Sessions/host strict clippy: cc-5388
• Root runtime-acceptance strict clippy: cc-5389
• diff-check and commitlint: clean

The fix admits current event_msg.item_completed/UserMessage records, retains legacy and response-only goal contexts, reconciles ordered response/current representations to one native identity, rejects malformed/non-user/image-only inputs, and recovers legacy cursors through receipt-backed restart-safe bounded replay without duplicating provider usage.

The separate process-global JSONL test-accounting race discovered during validation is tracked in #870 and is not implemented or masked here.

[ScriptedAlchemy]

Merged into codex/tracedecay-total-redesign-plan-reopened as 7f65fc9 (and duplicated by content in 3ac37c2); rollout-renderer coverage green via hauler cc-5989 (tracedecay-sessions codex 106 passed, tracedecay-capture codex 10 passed) and python3 scripts/test-render-codex-hook-inputs.py (4 tests OK).