feat(custom-model): generate Run-menu entries from saved endpoint profiles

.changeset/run-menu-custom-model-picker.md

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+'aicodeman': minor
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+**Custom model endpoints: Run-menu picker, and hardening from real llama-swap validation** (#430, follow-up to #393's HTTP-API-only cut). With **Custom model endpoints** on (App Settings → Models) and at least one saved endpoint carrying a discovered model, the Run dropdown grows a **Custom Endpoints** section generated live off the CLI registry's own `capabilities.customModelInjection` — one entry per (harness that can redirect to a custom endpoint, saved endpoint). Picking one launches that harness and applies the endpoint to it; with two or more discovered models a small, scrollable dialog asks which one first, the endpoint's `defaultModelId` marked but never auto-chosen. Endpoints also now re-discover themselves automatically every 5 minutes in the background, one unreachable endpoint never blocking the others.
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+Everything below was found and fixed against a **real llama-swap server**, not just unit tests:
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+- **Session-busy false refusal.** A freshly launched CLI reports itself `busy` for its own startup (spinner, workspace-trust check) well before the apply call would reach it, and the apply route correctly refuses to restart a session mid-turn — indistinguishable from a fresh boot. The picker now waits for the new session to go idle (bounded at 20s, never an error on timeout) before applying.
+- **Errors and confirmations you can actually read.** Toasts now default to sticky with a close button (errors always were meant to stay, but a fixed 3s timer silently hid them); a failed apply's real server-side reason (not a generic message) reaches the toast.
+- **"Both claude.ai and ANTHROPIC_API_KEY set" warning.** A custom-model Claude session now runs with an isolated `CLAUDE_CONFIG_DIR` (empty, no real credentials in it) so the injected API key never coexists with a stored OAuth login — `projects` is symlinked back to the real config dir so the response viewer/subagent windows/Read My Mind keep working. That isolated, otherwise-empty directory has none of a real profile's prior "Detected a custom API key — use it?" approvals either, which would otherwise re-ask on _every_ launch with nobody at a TTY to answer (and silently refuse the key on its own default); the apply step now pre-seeds that exact approval field the same way answering the prompt once by hand would.
+- **Context-window overflow.** Claude Code assumes a large default context window for a model id it doesn't recognize and never compacts, so a real local model's much smaller context silently overflowed (confirmed live: a stock ~33.7K-token system prompt against a 16384-token model). Discovery now also learns each model's real context length and applies it as `CLAUDE_CODE_MAX_CONTEXT_TOKENS` — sourced primarily from llama-swap's own `GET /running`, whose `cmd` field carries the launch flags (`--fit-ctx`/`-c`/`--ctx-size`) actually in effect, since `GET /props`'s `n_ctx` was confirmed live to report the model's theoretical/trained maximum rather than the real `--fit-ctx`-shrunk runtime context (a 154112-vs-16384 discrepancy, caught only because the fixed value still overflowed) — `/props` is now a fallback for a plain llama.cpp server with no `/running` at all.
+- **Context floor too small for Claude Code to even start.** Fixing the overflow above surfaced a second, unfixable-by-injection failure: Claude Code's own system prompt and tool schemas cost roughly 36.4K tokens on their own (confirmed live via an `in:0 out:0` failure on the very first message), which can exceed a small model's entire real context before any conversation history exists to trim — no `CLAUDE_CODE_MAX_CONTEXT_TOKENS` value fixes that, since it only governs when history gets compacted. Applying such a model now returns a warning (gated on the CLI registry declaring a `contextLengthVar`, so it's a no-op for every other harness) instead of launching straight into a guaranteed first-message failure, and the Run-menu picker shows it as an in-app dialog naming the model, its discovered context and the ~40K safe floor, with the actual fix spelled out: give the model an explicit larger `-c`/`--ctx-size` in llama-swap's config instead of relying on auto-fit, which optimizes for the biggest model that fits rather than the biggest context. "Launch anyway" is still one click away.
+- **The real root cause of "it still says opus, not my model."** llama.cpp runs exactly one model at a time; llama-swap unloads and reloads it on demand, which can take anywhere from a few seconds to well over a minute — long enough that a session mid-swap is indistinguishable from one that never left the native backend. Applying a selection now checks llama-swap's own `GET /running` first (feature-detected; a plain llama.cpp/OpenAI-compatible server has no such endpoint and is never checked); if switching would unload a model **another live session is actively using**, the apply is refused with a warning naming that session instead of silently switching, and a confirmation retry proceeds anyway. Either way, a sticky "loading model…" toast now covers the actual swap window until llama-swap reports the target model ready, so a prompt sent mid-swap reads as "loading," never as silence or an answer from whatever was loaded a moment before.
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+- **Claude's whole first-run sequence, on every single launch.** A fresh, otherwise-empty `CLAUDE_CONFIG_DIR` isn't just missing the API-key approval above — Claude Code treats it as a brand-new profile and replays the theme picker, the security-notes screen, the per-project "trust this folder?" dialog, and (running bypassed) a one-time permissions-bypass warning, every time, confirmed live. None of that shows up again for a real, already-onboarded profile. `customModelInjection`'s new `skipFirstRunPrompts` (claude's entry only) pre-seeds that same "already been through this" state — `hasCompletedOnboarding` and this session's own project trust into the same `.claude.json` the API-key approval merges into, `skipDangerousModePermissionPrompt` into `settings.json` — so a custom-model launch reaches the conversation exactly as fast as a native cloud one, with nobody there to click through a wizard.
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+Two more, from actually clicking through the swap-confirm and context-warning dialogs live: their z-index sat under the centred status banner, so a dialog could render fully hidden behind "Claude started — switching to llama-swap…"; and their Cancel/confirm buttons stacked instead of sitting side by side (`.btn-toolbar`'s own `display: flex` needs a row-layout parent it never had). Both dialogs now clear the banner and lay their buttons out centred, side by side.
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+- **A session's model getting silently swapped out later, not just at launch.** The conflict check above only ever runs at the moment a session is created or a model applied — confirmed live: a second Codex session picking a different model launched with no warning at all, because nothing conflicted at that exact instant, yet it silently evicted the first session's model regardless (llama.cpp runs one model at a time). There was no mechanism to catch a swap caused by a DIFFERENT session's own later, ordinary use. A new periodic sweep (`detectCustomModelSwapDisplacements`, every 20s, one `GET /running` per distinct endpoint with a live custom-model session) now compares each such session's own model against what's actually loaded, and a new `custom-model:swapped-out` SSE event drives a global toast naming the displaced session and what's now loaded instead — so you find out before typing into a session that's about to trigger yet another reload. Notifies once per displacement, clearing once a session's own model is loaded and ready again so a later, genuinely new displacement notifies again.
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+- **The loading banner's second line is now the real backend log line, not just a countdown.** llama-swap's `GET /api/events` SSE stream carries the actual `llama-server` process's own stdout (`load_model: loading model '<path>'`, `llama_server: model loaded`, tokenizer warnings, all of it) tagged `source: "upstream"`, distinct from llama-swap's own `source: "proxy"` request-access lines — confirmed live end-to-end through a real forced swap, and it correctly stays on the last thing llama.cpp said once the load goes quiet rather than clearing to blank. ⚠️ This feature's own first cut targeted `GET /logs` instead (the name that suggested it) and shipped a live-tested implementation against it before this live check caught that `/logs` carries ONLY the proxy request log and never once showed a single backend line, even seconds after a real, confirmed swap — corrected before merge, not after.
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+Remote (SSH) and Docker sessions are refused for now (400) — their restart reattaches the durable remote/in-container tmux rather than relaunching the agent.
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+- **The loading banner's countdown is gone, replaced by a generic disclaimer and a Cancel button.** Its size-scaled expected-time estimate and matching auto-timeout were both a guess dressed up as a fact — real load time depends on hardware this feature has no way to know, and a fixed number could kill a genuinely slow load partway through. The banner now says "this can take a while depending on your hardware and the model size", polls indefinitely, and carries a **Cancel** button that ends the wait and closes the session on the user's own call rather than a guessed deadline.
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+**One more, from watching it launch live: opencode, Codex, Gemini, Pi, Grok, DeepSeek and OMP now launch directly on the endpoint, with no restart at all.** Picking one of these seven from the Run-menu picker used to launch natively first, wait for it to settle, then restart it in place with the endpoint applied — a deliberate two-step design, but visibly a native boot immediately followed by a second one, worst on a CLI whose TUI fully reinitializes on a restart (confirmed live on Codex). `POST /api/quick-start` now accepts a `customModel` field and computes the same injection _before_ the session exists, launching straight onto the endpoint the first time — no visible relaunch, and it also runs the same llama-swap conflict check (warns before unloading a model another live session is using) at create time. Claude still uses the original launch-then-restart path for now (its own `--resume`-based restart is far less jarring, and `runClaude()`'s multi-tab and docker-config-drift-retry logic make folding it into the one-shot path separate work).