feat: add token usage tracking, context display, and dynamic context length (#132)

* fix: specify TS_NODE_PROJECT for dev:server script

ts-node/register resolves tsconfig from the entry file upward,
finding the root solution-style tsconfig.json (no compilerOptions).
This causes target to default to ES3, breaking MapIterator spread
syntax (TS2802). Set TS_NODE_PROJECT env var to point to the server
tsconfig which targets ES2024.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

* feat: add token usage tracking, context display, and dynamic context length

- Intercept SSE proxy to capture run.completed events and persist token
  usage (input_tokens, output_tokens) per session to SQLite/JSON store
- Display context usage bar in ChatInput showing used/total/remaining tokens
- Resolve actual context length from Hermes models_dev_cache.json based
  on the active profile's default model (fallback 200K), with 5min in-memory cache
- Move sessions-db.ts to db/hermes/ for unified database layer
- Add usage store with SQLite + JSON fallback (auto-migration via ensureTable)
- Fix proxy SSE path regex to match rewritten upstream path
- Fix route ordering: /sessions/usage before /sessions/:id to avoid 404
- Fetch per-session usage on session enter instead of batch
- Add unit tests for usage-store, db index, and proxy SSE interception

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

---------

Co-authored-by: Claude Opus 4.6 <noreply@anthropic.com>

packages/client/src/stores/hermes/chat.ts

@@ -1,5 +1,5 @@
 import { startRun, streamRunEvents, type ChatMessage, type RunEvent } from '@/api/hermes/chat'
-import { deleteSession as deleteSessionApi, fetchSession, fetchSessions, type HermesMessage, type SessionSummary } from '@/api/hermes/sessions'
+import { deleteSession as deleteSessionApi, fetchSession, fetchSessions, fetchSessionUsageSingle, type HermesMessage, type SessionSummary } from '@/api/hermes/sessions'
 import { defineStore } from 'pinia'
 import { ref, computed } from 'vue'
 import { useAppStore } from './app'
@@ -155,8 +155,6 @@ function mapHermesSession(s: SessionSummary): Session {
     model: s.model,
     provider: (s as any).billing_provider || '',
     messageCount: s.message_count,
-    inputTokens: s.input_tokens,
-    outputTokens: s.output_tokens,
   }
 }
 
@@ -340,8 +338,6 @@ export const useChatStore = defineStore('chat', () => {
           || (serverUsers === localUsers && serverAssistantLen >= localAssistantLen)
         if (serverIsAhead) {
           target.messages = mapped
-          target.inputTokens = detail.input_tokens
-          target.outputTokens = detail.output_tokens
           if (detail.title && !target.title) target.title = detail.title
           if (sid === activeSessionId.value) persistActiveMessages()
         }
@@ -363,8 +359,6 @@ export const useChatStore = defineStore('chat', () => {
               // our "don't retreat" guard above skipped it — the server is
               // now the authoritative source of truth.
               target.messages = mapped
-              target.inputTokens = detail.input_tokens
-              target.outputTokens = detail.output_tokens
               if (detail.title) target.title = detail.title
               if (sid === activeSessionId.value) persistActiveMessages()
               clearInFlight(sid)
@@ -447,8 +441,6 @@ export const useChatStore = defineStore('chat', () => {
       if (!target) return false
       const mapped = mapHermesMessages(detail.messages || [])
       target.messages = mapped
-      target.inputTokens = detail.input_tokens
-      target.outputTokens = detail.output_tokens
       if (detail.title) target.title = detail.title
       persistActiveMessages()
       return true
@@ -531,8 +523,6 @@ export const useChatStore = defineStore('chat', () => {
         if (serverIsAhead) {
           activeSession.value.messages = mapped
         }
-        activeSession.value.inputTokens = detail.input_tokens
-        activeSession.value.outputTokens = detail.output_tokens
         // Update title: use Hermes title, or fallback to first user message
         if (detail.title) {
           activeSession.value.title = detail.title
@@ -557,6 +547,15 @@ export const useChatStore = defineStore('chat', () => {
     if (readInFlight(sessionId) && !streamStates.value.has(sessionId)) {
       startPolling(sessionId)
     }
+
+    // Fetch token usage for this session from web-ui DB
+    try {
+      const usage = await fetchSessionUsageSingle(sessionId)
+      if (usage) {
+        activeSession.value.inputTokens = usage.input_tokens
+        activeSession.value.outputTokens = usage.output_tokens
+      }
+    } catch { /* non-critical */ }
   }
 
   function newChat() {
@@ -785,9 +784,15 @@ export const useChatStore = defineStore('chat', () => {
               if (lastMsg?.isStreaming) {
                 updateMessage(sid, lastMsg.id, { isStreaming: false })
               }
+              if (evt.usage) {
+                const target = sessions.value.find(s => s.id === sid)
+                if (target) {
+                  target.inputTokens = evt.usage.input_tokens
+                  target.outputTokens = evt.usage.output_tokens
+                }
+              }
               cleanup()
               updateSessionTitle(sid)
-              // IMPORTANT ordering: persist the final cache BEFORE clearing
               // the in-flight marker. If the browser is reloading right now
               // and kills us between the two localStorage writes, we want
               // the next page load to still see in-flight === true (so