feat(session): persist model tier overrides per session

Store per-session config in SQLite and route /model and /reset through command fast-paths so channel sessions keep independent model selection across reconnects and restarts.

src/tools/builtin/memory-read.ts

@@ -13,7 +13,7 @@ export function createMemoryReadTool(store: MemoryStore): Tool {
   return {
     name: 'memory.read',
     description:
-      'Read a persistent memory file by namespace. Available namespaces include "user" (user preferences and facts), "global" (cross-session knowledge), and session-specific namespaces. Returns the full contents of the memory file.',
+      'Read a persistent memory file by namespace. Available namespaces include "user" (user preferences and facts), "global" (cross-session knowledge), and session-specific namespaces. Supports structured categories by appending /facts, /preferences, /decisions, or /projects (for example: "user/facts"). Returns the full contents of the memory file.',
     inputSchema: {
       type: 'object',
       properties: {

src/tools/builtin/memory-search.ts

@@ -16,7 +16,8 @@ export function createMemorySearchTool(store: MemoryStore, hybridSearch?: Hybrid
     name: 'memory.search',
     description:
       'Search across all memory files for a keyword or phrase. Returns matching lines with surrounding context from every namespace.' +
-      (hybridSearch ? ' Uses semantic vector search combined with keyword matching for better results.' : ''),
+      (hybridSearch ? ' Uses semantic vector search combined with keyword matching for better results.' : '') +
+      ' Category namespaces (facts/preferences/decisions/projects) are searchable through the namespace path.',
     inputSchema: {
       type: 'object',
       properties: {

src/tools/builtin/memory-write.ts

@@ -15,7 +15,7 @@ export function createMemoryWriteTool(store: MemoryStore): Tool {
   return {
     name: 'memory.write',
     description:
-      'Write to a persistent memory file. Use mode="append" to add new information without overwriting existing content, or mode="replace" to overwrite the entire namespace.',
+      'Write to a persistent memory file. Use mode="append" to add new information without overwriting existing content, or mode="replace" to overwrite the entire namespace. Supports structured category namespaces like "user/facts", "user/preferences", "user/decisions", and "user/projects".',
     inputSchema: {
       type: 'object',
       properties: {