feat(webui): list every model with full usage on the Models tab

The Models tab ranks by requests by default and asks the server for
per-model detail. A table under the chart lists requests, tokens in,
tokens out and cost for each model. A model with no recorded cost that
is marked free shows a "free" badge instead of $0. The CSV export
includes every column and the free flag. admin_assets_gen.go is
regenerated.

Claude-Session: https://claude.ai/code/session_01V5jYJNxpDFdJkyyExpADrv

webui/src/stores/history.spec.ts

@@ -81,6 +81,42 @@ describe('useHistoryStore model ranking', () => {
     expect(paths.some((p) => p.startsWith('/admin/api/usage/history'))).toBe(false)
   })
 
+  // free-models-plan.md: a cost-default ranking hides every free model
+  // (its cost total is always 0) — the store now defaults to ranking by
+  // request count instead.
+  it('defaults modelMetric to "req", not "cost"', () => {
+    expect(useHistoryStore().modelMetric).toBe('req')
+  })
+
+  // free-models-plan.md: the ranking fetch always requests the per-model
+  // detail breakdown (requests/tokensIn/tokensOut/costMicroUsd/free), not
+  // just the single ranked `value` — lib/model-table-columns.ts's table
+  // renders every figure regardless of which metric is currently ranking.
+  it('always sends detail=1 on the ranking fetch, regardless of metric or prefix', async () => {
+    routeFetch({})
+    const history = useHistoryStore()
+    history.tab = 'models'
+    history.modelFilter = 'openai/'
+
+    await history.fetchModelRanking()
+
+    const rankingCall = mockedAdminFetch.mock.calls.map((c) => String(c[0])).find((p) => p.startsWith('/admin/api/usage/models'))
+    expect(rankingCall).toContain('detail=1')
+  })
+
+  // The scope picker's model list (fetchModelOptions) only ever needs ids
+  // — it must NOT pay for the detail breakdown the ranking fetch above
+  // does.
+  it('never sends detail=1 on the picker-list fetch', async () => {
+    routeFetch({})
+    const history = useHistoryStore()
+
+    await history.fetchModelOptions()
+
+    const optionsCall = mockedAdminFetch.mock.calls.map((c) => String(c[0])).find((p) => p.includes('/usage/models'))
+    expect(optionsCall).not.toContain('detail=1')
+  })
+
   it('ranks by the selected metric, independently of the tab', async () => {
     routeFetch({})
     const history = useHistoryStore()
@@ -410,7 +446,10 @@ describe('useHistoryStore: latest-request-wins', () => {
     history.tab = 'models'
     history.modelRanking = [{ id: 'alpha/a-model-1', value: 3 }]
 
-    history.setModelMetric('req')
+    // 'cost', not 'req' — the store now DEFAULTS to 'req' (free-models-
+    // plan.md), so setModelMetric('req') here would be a no-op early
+    // return rather than the actual change this test means to exercise.
+    history.setModelMetric('cost')
 
     expect(history.modelRanking).toEqual([])
   })
@@ -523,7 +562,7 @@ describe('useHistoryStore.setSelection (P12: batched, one fetch)', () => {
     const history = useHistoryStore()
     const callsBefore = mockedAdminFetch.mock.calls.length
 
-    history.setSelection({ scope: 'total', window: 'hour', tab: 'requests', modelMetric: 'cost' }) // all defaults
+    history.setSelection({ scope: 'total', window: 'hour', tab: 'requests', modelMetric: 'req' }) // all defaults
     await flush()
 
     expect(mockedAdminFetch.mock.calls.length).toBe(callsBefore)

webui/src/stores/history.ts

@@ -132,8 +132,14 @@ export const useHistoryStore = defineStore('history', {
     scope: 'total',
     window: 'hour' as HistoryWindow,
     tab: 'requests' as ChartTab,
-    /** Which metric the Models ranking ranks by — independent of `tab`. */
-    modelMetric: 'cost' as ModelMetric,
+    /**
+     * Which metric the Models ranking ranks by — independent of `tab`.
+     * Defaults to 'req' (free-models-plan.md), not 'cost': a cost-default
+     * ranking silently hides every free model (its cost total is always
+     * 0), and the picker/table both need free models to be reachable
+     * without the reader first knowing to switch metrics.
+     */
+    modelMetric: 'req' as ModelMetric,
     seriesByMetric: {} as Partial<Record<HistoryMetric, UsageHistoryPoint[]>>,
     /** The current Models-tab ranking. Empty means "nothing used in this window". */
     modelRanking: [] as AdminUsageModelEntry[],
@@ -391,8 +397,15 @@ export const useHistoryStore = defineStore('history', {
         // provider's models entirely, or return only a partial view of them
         // (the CONFIRMED problem this fixes).
         const prefixParam = this.modelFilter ? `&prefix=${encodeURIComponent(this.modelFilter)}` : ''
+        // detail=1 (free-models-plan.md): the Models tab's own ranking
+        // fetch always asks for the per-entry requests/tokensIn/tokensOut/
+        // costMicroUsd/free breakdown, not just the single ranked `value` —
+        // lib/model-table-columns.ts's table renders all four figures
+        // (plus the free badge) beside every row regardless of which
+        // metric is currently ranking. fetchModelOptions below stays
+        // detail-free: the scope picker only ever needs an id list.
         const res = await adminFetch<AdminUsageModelsResponse>(
-          `/admin/api/usage/models?metric=${this.modelMetric}&window=${this.window}&limit=${MODEL_RANKING_LIMIT}&span=${span}${prefixParam}`,
+          `/admin/api/usage/models?metric=${this.modelMetric}&window=${this.window}&limit=${MODEL_RANKING_LIMIT}&span=${span}${prefixParam}&detail=1`,
         )
         if (requestId !== this.seriesReqId) return
         this.modelRanking = res.models