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/memory/store.ts

@@ -1,5 +1,6 @@
 import { readFileSync, writeFileSync, existsSync, mkdirSync, readdirSync, statSync } from 'fs';
 import { join, relative, dirname } from 'path';
+import { MEMORY_CATEGORIES, categoryNamespace, isMemoryCategory, type MemoryCategory } from './categories.js';
 
 /**
  * Configuration for the MemoryStore.
@@ -11,6 +12,11 @@ export interface MemoryStoreConfig {
   maxContextTokens: number;
 }
 
+export interface PromptMemorySection {
+  title: string;
+  content: string;
+}
+
 /**
  * A single search result from scanning memory files.
  */
@@ -25,6 +31,11 @@ export interface SearchResult {
   context: string;
 }
 
+export interface SearchOptions {
+  categories?: MemoryCategory[];
+  baseNamespacePrefix?: string;
+}
+
 /**
  * Manages persistent markdown memory files on disk.
  *
@@ -94,14 +105,72 @@ export class MemoryStore {
     this._dirtyNamespaces.add(namespace);
   }
 
+  /** Read content for a category under a base namespace. */
+  readCategory(baseNamespace: string, category: MemoryCategory): string {
+    return this.read(categoryNamespace(baseNamespace, category));
+  }
+
+  /** Write content for a category under a base namespace. */
+  writeCategory(baseNamespace: string, category: MemoryCategory, content: string, mode: 'append' | 'replace'): void {
+    this.write(categoryNamespace(baseNamespace, category), content, mode);
+  }
+
+  /** List categories that currently exist under a base namespace. */
+  listCategories(baseNamespace: string): MemoryCategory[] {
+    const categorySet = new Set<MemoryCategory>();
+    const prefix = `${baseNamespace}/`;
+
+    for (const namespace of this.listNamespaces()) {
+      if (!namespace.startsWith(prefix)) {
+        continue;
+      }
+
+      const suffix = namespace.slice(prefix.length);
+      if (suffix.includes('/')) {
+        continue;
+      }
+
+      if (isMemoryCategory(suffix)) {
+        categorySet.add(suffix);
+      }
+    }
+
+    return MEMORY_CATEGORIES.filter(category => categorySet.has(category));
+  }
+
+  /** Read all category files under a base namespace. */
+  readAllCategories(baseNamespace: string): Partial<Record<MemoryCategory, string>> {
+    const result: Partial<Record<MemoryCategory, string>> = {};
+
+    for (const category of this.listCategories(baseNamespace)) {
+      const content = this.readCategory(baseNamespace, category);
+      if (content.length > 0) {
+        result[category] = content;
+      }
+    }
+
+    return result;
+  }
+
   /**
    * Search across all memory files for a keyword or phrase.
    * Performs case-insensitive line-by-line matching.
    * Returns matching lines with 1 line of context above and below.
    */
-  search(query: string): SearchResult[] {
+  search(query: string, opts?: SearchOptions): SearchResult[] {
     const results: SearchResult[] = [];
-    const namespaces = this.listNamespaces();
+    const namespaces = this.listNamespaces().filter((namespace) => {
+      if (opts?.baseNamespacePrefix && !namespace.startsWith(opts.baseNamespacePrefix)) {
+        return false;
+      }
+
+      if (opts?.categories && opts.categories.length > 0) {
+        const suffix = namespace.split('/').pop() ?? '';
+        return isMemoryCategory(suffix) && opts.categories.includes(suffix);
+      }
+
+      return true;
+    });
     const lowerQuery = query.toLowerCase();
 
     for (const namespace of namespaces) {
@@ -178,23 +247,13 @@ export class MemoryStore {
    * (estimated at 4 characters per token).
    */
   getContextForPrompt(): string {
-    const userMemory = this.read('user');
-    const globalMemory = this.read('global');
+    const sections = this.getPromptSections().map((section) => `## ${section.title}\n\n${section.content}`);
 
     // Nothing to inject
-    if (userMemory.length === 0 && globalMemory.length === 0) {
+    if (sections.length === 0) {
       return '';
     }
 
-    const sections: string[] = [];
-
-    if (userMemory.length > 0) {
-      sections.push(`## User Memory\n\n${userMemory}`);
-    }
-    if (globalMemory.length > 0) {
-      sections.push(`## Global Memory\n\n${globalMemory}`);
-    }
-
     const full = sections.join('\n\n');
 
     // Truncate to fit within the token budget (estimate: 4 chars ≈ 1 token)
@@ -205,6 +264,45 @@ export class MemoryStore {
     return full.slice(0, maxChars);
   }
 
+  /** Build memory sections used by prompt injectors. */
+  getPromptSections(): PromptMemorySection[] {
+    const userMemory = this.read('user');
+    const globalMemory = this.read('global');
+    const userCategoryMemory = this.readAllCategories('user');
+    const globalCategoryMemory = this.readAllCategories('global');
+
+    const sections: PromptMemorySection[] = [];
+
+    if (userMemory.length > 0) {
+      sections.push({ title: 'User Memory', content: userMemory });
+    }
+    if (globalMemory.length > 0) {
+      sections.push({ title: 'Global Memory', content: globalMemory });
+    }
+
+    for (const category of MEMORY_CATEGORIES) {
+      const content = userCategoryMemory[category];
+      if (content) {
+        sections.push({
+          title: `User ${this._categoryLabel(category)}`,
+          content,
+        });
+      }
+    }
+
+    for (const category of MEMORY_CATEGORIES) {
+      const content = globalCategoryMemory[category];
+      if (content) {
+        sections.push({
+          title: `Global ${this._categoryLabel(category)}`,
+          content,
+        });
+      }
+    }
+
+    return sections;
+  }
+
   // ---------------------------------------------------------------------------
   // Private helpers
   // ---------------------------------------------------------------------------
@@ -236,4 +334,8 @@ export class MemoryStore {
 
     return namespaces;
   }
+
+  private _categoryLabel(category: MemoryCategory): string {
+    return `${category.charAt(0).toUpperCase()}${category.slice(1)}`;
+  }
 }