Agent preset switch on the new-session screen is silently discarded (chip falls back to Standard mode)

[neuviletteflux]

Summary

On the new-session screen, choosing a non-default Agent preset ("Creator mode") is silently discarded: no RPC is sent, no toast is shown, and the chip falls back to the session's recorded preset ("Standard mode"). Reproduced on the desktop profile of 0.2.1-rc.2; a web-profile deployment of the same npm package switches correctly.

Environment

• @deepseek-ai/dsh 0.2.1-rc.2 (desktop app and CLI are the same npm package)
• macOS (Apple Silicon); built-in presets only (standard / ptc / minimal / cordis), coding tools enabled
• desktop profile: ~235 sessions. web profile: ~10 sessions.

Steps

1. Open a new (blank) session — the preset chip shows "Standard mode".
2. Open the chip and pick "Creator mode".
3. Observe the chip, the toast, and the session log.

Expected

Chip shows "Creator mode"; the Host records agent-preset/selected: cordis; the first turn is composed on cordis.

Actual

• the chip returns to "Standard mode" immediately, and after a full page reload;
• no toast, no error message;
• the session log has no agent-preset/selected event;
• instrumenting agentPresets.* on the Host shows list / retain calls but no select.

Root cause (as observed)

AgentPresetSeatController.apply() in @deepseek-ai/dsh-client-ui-agent-preset gates the Host call on the client's session-list row:

if (!session.blank || presetOf(session) === staged) {
  this.clearStage();   // silent drop: no RPC, no toast
  return;
}

For a new session on the desktop profile this row is published with blank: false, while every other source says blank:

| Source | blank | | --- | --- | | client sessions.list row (what the seat reads) | false | | client manager.summaries[sid].blank | true | | sessionListMetadata.blank projection | true | | Host sessionController.list() | true | | Host turnBoundary | lastTurn: 0 |

So !session.blank is taken, the staged pick is cleared silently, and the chip re-renders from presetOf(session) = standard.

Calling agentPresets.select(agent, 'cordis') directly on the same blank session succeeds and the chip updates, so the Host and the display path are fine.

Why desktop and not web (hypothesis)

New sessions have seq = 3 (three seed events). The Host list summary falls back to blank: metadata?.blank ?? session.seq === 0; if a list snapshot is produced before that session's projections are ready, the row goes out as blank: false. The client merge is monotonic (blank: existing.blank && mutation.summary.blank — "Blank only lowers"), so a later true never repairs it. A large session list on desktop (235 vs 10) widens that window; on the affected client, sessions.refresh() does not repair the row either.

Suggested fixes

1. Seat: stop pre-gating on the list row. Use the turnBoundary projection, or call agentPresets/select and surface the existing agent-preset/locked refusal as a toast.
2. List projection: keep sessions.list rows consistent with manager.summaries / sessionListMetadata, and give the monotonic merge a repair path.
3. Feedback: the !session.blank branch is currently silent; it should report a refusal.

Notes

• Related: dsh web对话过程中似乎没办法切换使用模式 #29 — switching after the first turn is impossible by design; this report is about switching before it, which should work but is silently dropped.
• Happy to provide a screen recording, or to bisect the desktop bundle list (the web profile has a smaller plugin set) if that helps.