Web UI: add token usage dashboard (#10072)

* feat(ui): Token Usage dashboard with session analytics

Adds a comprehensive Token Usage view to the dashboard:

Backend:
- Extended session-cost-usage.ts with per-session daily breakdown
- Added date range filtering (startMs/endMs) to API endpoints
- New sessions.usage, sessions.usage.timeseries, sessions.usage.logs endpoints
- Cost breakdown by token type (input/output/cache read/write)

Frontend:
- Two-column layout: Daily chart + breakdown | Sessions list
- Interactive daily bar chart with click-to-filter and shift-click range select
- Session detail panel with usage timeline, conversation logs, context weight
- Filter chips for active day/session selections
- Toggle between tokens/cost view modes (default: cost)
- Responsive design for smaller screens

UX improvements:
- 21-day default date range
- Debounced date input (400ms)
- Session list shows filtered totals when days selected
- Context weight breakdown shows skills, tools, files contribution

* fix(ui): restore gatewayUrl validation and syncUrlWithSessionKey signature

- Restore normalizeGatewayUrl() to validate ws:/wss: protocol
- Restore isTopLevelWindow() guard for iframe security
- Revert syncUrlWithSessionKey signature (host param was unused)

* feat(ui): Token Usage dashboard with session analytics

Adds a comprehensive Token Usage view to the dashboard:

Backend:
- Extended session-cost-usage.ts with per-session daily breakdown
- Added date range filtering (startMs/endMs) to API endpoints
- New sessions.usage, sessions.usage.timeseries, sessions.usage.logs endpoints
- Cost breakdown by token type (input/output/cache read/write)

Frontend:
- Two-column layout: Daily chart + breakdown | Sessions list
- Interactive daily bar chart with click-to-filter and shift-click range select
- Session detail panel with usage timeline, conversation logs, context weight
- Filter chips for active day/session selections
- Toggle between tokens/cost view modes (default: cost)
- Responsive design for smaller screens

UX improvements:
- 21-day default date range
- Debounced date input (400ms)
- Session list shows filtered totals when days selected
- Context weight breakdown shows skills, tools, files contribution

* fix: usage dashboard data + cost handling (#8462) (thanks @mcinteerj)

* Usage: enrich metrics dashboard

* Usage: add latency + model trends

* Gateway: improve usage log parsing

* UI: add usage query helpers

* UI: client-side usage filter + debounce

* Build: harden write-cli-compat timing

* UI: add conversation log filters

* UI: fix usage dashboard lint + state

* Web UI: default usage dates to local day

* Protocol: sync session usage params (#8462) (thanks @mcinteerj, @TakHoffman)

---------

Co-authored-by: Jake McInteer <mcinteerj@gmail.com>

src/gateway/protocol/index.ts

@@ -161,6 +161,8 @@ import {
   SessionsResetParamsSchema,
   type SessionsResolveParams,
   SessionsResolveParamsSchema,
+  type SessionsUsageParams,
+  SessionsUsageParamsSchema,
   type ShutdownEvent,
   ShutdownEventSchema,
   type SkillsBinsParams,
@@ -271,6 +273,8 @@ export const validateSessionsDeleteParams = ajv.compile<SessionsDeleteParams>(
 export const validateSessionsCompactParams = ajv.compile<SessionsCompactParams>(
   SessionsCompactParamsSchema,
 );
+export const validateSessionsUsageParams =
+  ajv.compile<SessionsUsageParams>(SessionsUsageParamsSchema);
 export const validateConfigGetParams = ajv.compile<ConfigGetParams>(ConfigGetParamsSchema);
 export const validateConfigSetParams = ajv.compile<ConfigSetParams>(ConfigSetParamsSchema);
 export const validateConfigApplyParams = ajv.compile<ConfigApplyParams>(ConfigApplyParamsSchema);
@@ -412,6 +416,7 @@ export {
   SessionsResetParamsSchema,
   SessionsDeleteParamsSchema,
   SessionsCompactParamsSchema,
+  SessionsUsageParamsSchema,
   ConfigGetParamsSchema,
   ConfigSetParamsSchema,
   ConfigApplyParamsSchema,
@@ -541,6 +546,7 @@ export type {
   SessionsResetParams,
   SessionsDeleteParams,
   SessionsCompactParams,
+  SessionsUsageParams,
   CronJob,
   CronListParams,
   CronStatusParams,