Best possible solution:

Land a corrected narrow patch that keeps heartbeat model overrides scoped to heartbeat runs, preserves only valid pre-existing runtime model identity, covers legacy model-only session entries, leaves non-heartbeat persistence unchanged, and satisfies the active changelog gate.

Do we have a high-confidence way to reproduce the issue?

Yes. The linked issue gives a concrete config and before/after session_status evidence; current main also reproduces at code level because heartbeat run metadata is unconditionally written back into the shared session entry.

Is this the best way to solve the issue?

No, not as currently written. The preserveRuntimeModel direction is maintainable, but the preserve branch must not pair a preserved model with the heartbeat provider, and the changelog line must pass the repository PR gate.

Full review comments:

• [P2] Avoid pairing legacy models with the heartbeat provider — src/agents/command/session-store.ts:134-135
  When a stored entry has model but no modelProvider, this branch preserves the old model while falling back to the heartbeat providerUsed. That can persist pairs like ollama/claude-opus-4-6 instead of preserving the legacy model under its existing semantics; add a model-only regression and avoid borrowing the heartbeat provider for preserved models.
  Confidence: 0.9
• [P2] Fix the changelog line for PR gates — CHANGELOG.md:20
  The added changelog line references only the fixed issue, thanks a different handle, and is inserted above existing Fixes entries. The PR gate requires the current PR reference, Thanks @zhangguiping-xydt, and section-tail placement before this can merge.
  Confidence: 0.96

Overall correctness: patch is incorrect
Overall confidence: 0.88

Acceptance criteria:

• pnpm test src/agents/command/session-store.test.ts
• pnpm exec oxfmt --check --threads=1 src/agents/command/session-store.ts src/agents/command/session-store.test.ts CHANGELOG.md
• pnpm check:changed in Testbox before handoff if promoted

What I checked:

• Current main persistence path: Current main derives modelUsed and providerUsed from the completed run result and then writes contextTokens plus setSessionRuntimeModel(next, { provider: providerUsed, model: modelUsed }) for every persisted run, with no heartbeat-specific preservation branch. (src/agents/command/session-store.ts:78, e0cc374b07c1)
• Heartbeat caller on main: The current heartbeat caller only suppresses lastInteractionAt freshness for cron/heartbeat runs; it does not preserve or restore the prior runtime model metadata after a heartbeat turn. (src/agents/agent-command.ts:1158, e0cc374b07c1)
• PR preserve branch defect: The PR preserve branch uses entry.modelProvider ?? providerUsed with entry.model ?? modelUsed, so a legacy entry with only model can be paired with the heartbeat provider from the just-finished run. (src/agents/command/session-store.ts:134, 13e9461223e0)
• Model-only entries are valid state: Current session normalization keeps a runtime model even when modelProvider is absent, and merge logic explicitly deletes a stale provider when a model is patched without a provider, so model-only entries need a safe preserve path. (src/config/sessions/types.ts:376, e0cc374b07c1)
• Changelog gate mismatch: The PR changelog gate requires the added line to reference the current PR, be appended at the section tail, and include Thanks @<contrib>; the PR line references only the fixed issue, thanks @zhang-guiping, and is inserted above existing section entries. (scripts/pr-lib/changelog.sh:177, e0cc374b07c1)
• Related discussion: The linked issue provides concrete heartbeat-vs-primary model setup and before/after status output; the existing ClawSweeper comment on this PR already flagged the same two narrow blockers.

Likely related people:

• steipete: Recent commit history and local blame show repeated maintenance of session-store, agent-command, runtime status metadata, session reset behavior, and model/runtime persistence near this path. (role: recent maintainer; confidence: high; commits: e5dc0e6d15ea, 566d2d73a323, 5f81147c4d0c; files: src/agents/command/session-store.ts, src/agents/agent-command.ts, src/config/sessions/types.ts)
• jalehman: Recent work in agent-command.ts added compaction model fallback handling and preserved fallback metadata, which is adjacent to per-run model metadata and persistence semantics. (role: adjacent owner; confidence: medium; commits: c09884614864; files: src/agents/agent-command.ts)
• vincentkoc: Recent model runtime normalization work touched provider/runtime selection and status labeling, which overlaps the provider/model identity contract involved in this PR. (role: adjacent owner; confidence: medium; commits: aa27e27f3606; files: src/config/sessions/types.ts, src/agents/agent-command.ts)

Codex review notes: model gpt-5.5, reasoning high; reviewed against e0cc374b07c1.