#21847: fix(session): /new and /reset no longer carry over model overrides

## Summary After setting a per-session model override (e.g. via `/model opus`), running `/new` or `/reset` would start a fresh session but the model override persisted. The agent continued running on the overridden model instead of the configured default. ## Root Cause In `src/auto-reply/reply/session.ts`, a carry-over block runs when `resetTriggered` is true to preserve deliberate UX preferences across `/new` so users don't have to re-enable them every time: ```typescript if (resetTriggered && entry) { persistedThinking = entry.thinkingLevel; // ✅ intentional persistedVerbose = entry.verboseLevel; // ✅ intentional persistedReasoning = entry.reasoningLevel; // ✅ intentional persistedTtsAuto = entry.ttsAuto; // ✅ intentional persistedModelOverride = entry.modelOverride; // ❌ should not carry over persistedProviderOverride = entry.providerOverride; // ❌ should not carry over } ``` Model selection is a per-session choice, not a UX preference. `/new` and `/reset` mean "start fresh" — the model should return to the configured default, consistent with how message history and compaction state behave. ## Fix Remove `modelOverride` and `providerOverride` from the `resetTriggered` carry-over block. They continue to be persisted on session resume (non-reset path) as before. ## Changes - `src/auto-reply/reply/session.ts` — remove 2 lines - `src/auto-reply/reply/session.test.ts` — 2 new test cases ## Tests | Scenario | Result | |---|---| | `/new` does NOT carry over `modelOverride` | ✅ | | `/new` does NOT carry over `providerOverride` | ✅ | | `/new` still carries over `thinkingLevel`, `verboseLevel`, etc. | ✅ | | Resume (no reset) still preserves `modelOverride` | ✅ | | All 40 session tests pass | ✅ | Fixes #21725 <!-- greptile_comment --> <h3>Greptile Summary</h3> Removes `modelOverride` and `providerOverride` from the reset carry-over block in `session.ts`, ensuring `/new` and `/reset` commands return to the configured default model instead of persisting per-session overrides. The fix correctly distinguishes between UX preferences (thinking/verbose/reasoning levels) that should carry over and model selection that should reset. - **Main change**: Removed 2 lines from the `resetTriggered` carry-over block (lines 257-258) - **Preserved behavior**: Model overrides still persist on session resume (non-reset path, lines 244-245) - **Test coverage**: Added 2 comprehensive test cases covering both reset and resume scenarios <h3>Confidence Score: 5/5</h3> - This PR is safe to merge with minimal risk - The fix is a minimal, well-targeted 2-line deletion that addresses the root cause precisely. The logic is sound: model selection is correctly treated as a per-session choice rather than a UX preference. Test coverage is comprehensive with 2 new test cases validating both the fix (reset doesn't carry over) and the preserved behavior (resume still carries over). All 40+ session tests reportedly pass. - No files require special attention _{Last reviewed commit: f3eea17} <!-- greptile_other_comments_section --> <!-- /greptile_comment -->