feat(models): refresh model capabilities from models.dev in the background

Capability tables are hand-maintained, so a model gains vision or a wider
context only when someone notices and edits the file. This adds a daily
sync that fills the gap for models already in the registry.

How it decides:

- Modalities (vision/pdf/audio/video) belong to the MODEL — every gateway
  serving glm-5.3-flash serves the same weights — so they are keyed by
  model id and shared. A majority of sources must declare one, which keeps
  out lone mis-declarations: minimax-m2.5 (1 of 45), glm-4.7 (1 of 44) and
  gpt-oss-120b (2 of 76) are text-only despite a reseller claiming vision.
- Context/output limits belong to the GATEWAY — each truncates differently
  (glm-5 ships as 202752/16384 on one host and 204800/131072 on another) —
  so they are keyed by provider + model and only the matching provider's
  own numbers are trusted.

Both layers are strictly additive and sit BELOW the hand-written tables,
which short-circuit first. A capability already true stays true.

Mechanics: worker thread (the 4MB parse would block the loop ~20ms),
ETag so an unchanged catalog costs one empty request, 60s startup delay,
30min backoff on failure, MODEL_CATALOG_SYNC=off to disable. Only the
~57KB delta is kept; lookups cost ~0.1us via an mtime-guarded cache.

capabilities.js is bundled into the browser through useModelCaps, so it
cannot import node:fs — the server injects the reader via
setCatalogSource() from instrumentation.

visionPatterns.js is the last resort: a model nobody has catalogued yet
still accepts images when its id says so (qwen3-vl-plus, glm-4.6v, llava),
with image-generation and embedding ids excluded.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

open-sse/providers/catalogOverride.js

@@ -0,0 +1,72 @@
+// Read side of the model catalog synced from models.dev.
+//
+// The file is the source of truth; the only thing held in memory is a parsed
+// copy dropped as soon as the file's mtime changes. getCapabilitiesForModel is
+// synchronous and runs per request, so the hot path is one stat (~1us) and the
+// parse (~0.1ms on a ~18KB file) only reruns after a sync.
+
+import fs from "node:fs";
+import path from "node:path";
+import { DATA_DIR } from "@/lib/dataDir.js";
+
+export const CATALOG_FILE = path.join(DATA_DIR, "model-catalog.json");
+// Trimmed upstream catalog, read by the add-models skill (not by the router).
+export const CATALOG_RAW_FILE = path.join(DATA_DIR, "model-catalog-raw.json");
+
+const EMPTY = { models: {}, providers: {} };
+let cache = EMPTY;
+let cachedMtime = -1;
+
+// "zai-org/GLM-4.6V:free" -> "glm-4.6v"
+function baseId(model) {
+  if (!model) return "";
+  const withoutVendor = model.includes("/") ? model.split("/").pop() : model;
+  return withoutVendor.toLowerCase().split(":")[0];
+}
+
+function load() {
+  let mtime;
+  try {
+    mtime = fs.statSync(CATALOG_FILE).mtimeMs;
+  } catch {
+    cache = EMPTY;
+    cachedMtime = -1;
+    return cache;
+  }
+  if (mtime === cachedMtime) return cache;
+
+  cachedMtime = mtime;
+  try {
+    const parsed = JSON.parse(fs.readFileSync(CATALOG_FILE, "utf8"));
+    cache = { models: parsed?.models || {}, providers: parsed?.providers || {} };
+  } catch {
+    cache = EMPTY;
+  }
+  return cache;
+}
+
+// Modality is a property of the model itself — any gateway serving it inherits
+// the same image/video/pdf support, so this is keyed by model id alone.
+export function getCatalogModalities(model) {
+  return load().models[baseId(model)] || null;
+}
+
+// Context and output limits are a property of the gateway, not the model: each
+// one truncates differently, so these stay keyed by provider + model.
+export function getCatalogLimits(provider, model) {
+  const byProvider = provider && load().providers[provider];
+  if (!byProvider) return null;
+  return byProvider[model] || byProvider[baseId(model)] || null;
+}
+
+// Force a re-read on the next lookup (called right after a sync writes the file).
+export function invalidateCatalog() {
+  cachedMtime = -1;
+}
+
+// Hand the reader to capabilities.js. That module is bundled into the browser
+// too, so it cannot import this file directly — the server pushes it in.
+export async function installCatalogSource() {
+  const { setCatalogSource } = await import("./capabilities.js");
+  setCatalogSource({ getModalities: getCatalogModalities, getLimits: getCatalogLimits });
+}