New Session uses the wrong model when an agent is selected #38333

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1. github-actions commented on Jul 22, 2026

   

   github-actionsBot

   on Jul 22, 2026 – with GitHub Actions

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   This issue might be a duplicate of existing issues. Please check:

   • Web: switching sessions overwrites user-selected model with agent default #35899: Web UI switching sessions overwrites user-selected model with agent default (similar symptom: agent model not correctly applied to session)
   • Model selection silently reverts after answering a question #34207: Model selection silently reverts after answering a question (model gets overwritten by agent default in similar circumstances)

   If your issue is specifically about the New Session dialog not applying the agent's configured model when first starting a session, it may be distinct enough to stand on its own — but it's worth checking those issues first to see if they cover the same root cause.
2. LLawliet444 commented on Jul 22, 2026

   

   LLawliet444

   on Jul 22, 2026

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   I’d like to take this. I reproduced the likely state-priority issue in the new-session composer: the persisted prompt model is preferred over the newly selected agent’s configured model. I’ll add a regression test ensuring an agent selection initializes the new session with that agent’s model while preserving an explicit subsequent model choice.
3. Dominic-Leidenfrost commented on Aug 5, 2026

   

   Dominic-Leidenfrost

   on Aug 5, 2026

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   Hit this on 1.18.13 and dug into it — posting the root cause, since it's a bit more specific than the title suggests and I don't think #38372 as it stands fully closes it.

   Two things combine.

   packages/app/src/pages/session/composer/prompt-model-selection.ts orders the persisted draft model ahead of the agent's:

   const key = [prompt.model.current(), input.agent()?.model, configured(), recent(), fallback()].find(
     (item): item is ModelKey => !!item && valid(item),
   )

   And openNewTab in packages/app/src/components/titlebar.tsx seeds a new draft with the previous tab's model:

   const model = tabs.stateValue<PromptSession>(sessionTab, "prompt")?.model.current()
   tabs.newDraft({ server: sessionTab.server, directory: activeSession.directory }, "", model)

   So the wrong model is already in the draft before the agent is ever consulted. #38372 hooks the agent select callback, which covers step 3 of the repro here — but a new tab opened without touching the agent picker still starts on the inherited model, because the select never fires.

   Worth flagging: #39319 is the same code path from the opposite side, where the agent's model overwriting a manual pick is the complaint. A fix that just makes the agent model win harder will reopen that one.

   What worked for me is scoping rather than reordering: tag the persisted selection with the agent it was made under, and only honour it while that agent is active. Values without a tag — pre-existing drafts, and models inherited via openNewTab — lose to a configured agent model, but are still honoured for agents that have no model configured, so the inheritance behaviour stays intact where it's unambiguous.

   That gives:

   • new session and agent switch land on the agent's model (this issue)
   • a manual pick survives across turns while you stay on that agent (Manually selected model reverts to the agent's configured model after every turn #39319)
   • switching away and back restores it

   I've been running this against 1.18.13 as a patched bundle rather than a source build. Happy to open a PR against dev if that direction looks right.
4. fobiat commented on Sep 17, 2026

   

   fobiat

   on Sep 17, 2026

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   Reproduced against current app source using a production build, isolated --pure server, and a local fake provider. A draft copied Alpha/low from its source session; selecting Beta changed only the agent label, and the provider received model=alpha, reasoning_effort=low.

   I have a focused fix for deliberate agent selection and both cycling directions. It updates the draft model/variant together with the agent, retains draft settings for agents without defaults, and leaves later manual selections intact. Browser verification now captures beta/high after selecting Beta. New-tab inheritance without an agent-selection action is intentionally unchanged; changing that precedence needs a separate decision. The earlier #38372 and #40604 were closed without merging.
5. papue commented on Sep 29, 2026

   

   papue

   on Sep 29, 2026

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   Confirming this is still reproducible on OpenCode Desktop 1.18.33 / Windows 11.

   What I observe:

   • New Session → agent and configured model switch correctly.
   • + new tab with no other tab open → agent and configured model switch correctly.
   • + new tab while another tab is already open → the model becomes sticky and does not follow the selected primary agent's configured model.
6. neriousy commented on Oct 19, 2026

   

   neriousy

   on Oct 19, 2026

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   V2 applies the selected agent's configured model when you change agents in the new-session composer, rather than keeping an inherited model from another agent. Explicit model choices are remembered per agent when switching back. To get v2: npm i -g @opencode/cli@latest or curl -fsSL https://opencode.ai/v2/install | bash (desktop: update the app). If you still see this on v2, please open a new issue with the details.
7. neriousy

   closed this as completedon Oct 19, 2026