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src/providers/mssql/queries/modelconversation.js

@@ -5,15 +5,25 @@ export const MODELCONVERSATION_COLUMNS = `
     model,
     created_at,
     updated_at,
-    state
+    state,
+    started_by
 `;
 
 export const LIST_BY_COMPANYUSER = `
 SELECT
-${MODELCONVERSATION_COLUMNS}
-FROM modelconversation
-WHERE companyuser_id = @companyuserId
-ORDER BY updated_at DESC, id DESC
+${MODELCONVERSATION_COLUMNS},
+    (
+        SELECT m.message
+        FROM modelmessage m
+        WHERE m.id = (
+            SELECT MIN(f.id)
+            FROM modelmessage f
+            WHERE f.conversation_id = c.id AND f.role = 'user'
+        )
+    ) AS first_user_message
+FROM modelconversation c
+WHERE c.companyuser_id = @companyuserId
+ORDER BY c.updated_at DESC, c.id DESC
 `;
 
 export const GET_BY_COMPANYUSER_AND_ID = `
@@ -27,7 +37,8 @@ export const CREATE = `
 INSERT INTO modelconversation (
     companyuser_id,
     provider,
-    model
+    model,
+    started_by
 )
 OUTPUT
     INSERTED.id,
@@ -36,11 +47,13 @@ OUTPUT
     INSERTED.model,
     INSERTED.created_at,
     INSERTED.updated_at,
-    INSERTED.state
+    INSERTED.state,
+    INSERTED.started_by
 VALUES (
     @companyuserId,
     @provider,
-    @model
+    @model,
+    @startedBy
 )
 `;
 
@@ -69,11 +82,30 @@ OUTPUT
     INSERTED.model,
     INSERTED.created_at,
     INSERTED.updated_at,
-    INSERTED.state
+    INSERTED.state,
+    INSERTED.started_by
 WHERE id = @id AND companyuser_id = @companyuserId
 `;
 
+/**
+ * Deletes a conversation and, because started_by is not a foreign key, the whole chain of
+ * subagent conversations below it (started_by -> id, recursively) in a single statement.
+ * Messages go with their conversations via ON DELETE CASCADE. rowsAffected is 0 only when
+ * the root conversation does not exist for this user (a root always yields >= 1 row).
+ */
 export const DELETE_BY_COMPANYUSER_AND_ID = `
+WITH subtree AS (
+    SELECT id
+    FROM modelconversation
+    WHERE id = @id AND companyuser_id = @companyuserId
+
+    UNION ALL
+
+    SELECT c.id
+    FROM modelconversation c
+    INNER JOIN subtree s ON c.started_by = s.id
+    WHERE c.companyuser_id = @companyuserId
+)
 DELETE FROM modelconversation
-WHERE id = @id AND companyuser_id = @companyuserId
+WHERE id IN (SELECT id FROM subtree)
 `;

src/providers/mssql/schema.js

@@ -819,10 +819,12 @@ BEGIN
         created_at DATETIME2 NOT NULL CONSTRAINT DF_modelconversation_created_at DEFAULT SYSUTCDATETIME(),
         updated_at DATETIME2 NOT NULL CONSTRAINT DF_modelconversation_updated_at DEFAULT SYSUTCDATETIME(),
         state NVARCHAR(20) NOT NULL CONSTRAINT DF_modelconversation_state DEFAULT 'idle',
+        started_by INT NULL, -- id of the conversation that started this one as a subagent; deliberately NOT a foreign key
         CONSTRAINT FK_modelconversation_companyuser FOREIGN KEY (companyuser_id) REFERENCES companyuser(id) ON DELETE CASCADE,
         CONSTRAINT CK_modelconversation_state CHECK (state IN ('idle', 'busy'))
     );
     CREATE INDEX IX_modelconversation_companyuser ON modelconversation (companyuser_id, updated_at);
+    CREATE INDEX IX_modelconversation_started_by ON modelconversation (started_by);
 END
 `;
 

src/providers/sqlite3/schema.js

@@ -511,9 +511,11 @@ CREATE TABLE IF NOT EXISTS modelconversation (
     created_at TEXT NOT NULL DEFAULT (${UTC_NOW}),
     updated_at TEXT NOT NULL DEFAULT (${UTC_NOW}),
     state TEXT NOT NULL DEFAULT 'idle' CHECK (state IN ('idle', 'busy')),
+    started_by INTEGER, -- id of the conversation that started this one as a subagent; deliberately NOT a foreign key
     FOREIGN KEY (companyuser_id) REFERENCES companyuser(id) ON DELETE CASCADE
 );
 CREATE INDEX IF NOT EXISTS IX_modelconversation_companyuser ON modelconversation (companyuser_id, updated_at);
+CREATE INDEX IF NOT EXISTS IX_modelconversation_started_by ON modelconversation (started_by);
 `;
 
 

src/store/modelconversation/create.js

@@ -15,9 +15,10 @@ export default function create(provider) {
    * @param {object} input - Conversation input.
    * @param {string} input.provider - LLM provider name.
    * @param {string} input.model - Model identifier.
+   * @param {number|null} [input.started_by] - Id of the conversation that starts this one as a subagent (unenforced reference; omit/null for a top-level conversation).
    * @param {object} [tx] - Optional transaction to run within.
-   * @returns {Promise<{id: number, companyuser_id: number, provider: string, model: string, created_at: string, updated_at: string, state: string}>}
-   * @throws {Error} 'Provider required' or 'Model required'.
+   * @returns {Promise<{id: number, companyuser_id: number, provider: string, model: string, created_at: string, updated_at: string, state: string, started_by: number|null}>}
+   * @throws {Error} 'Provider required', 'Model required' or 'Invalid started_by'.
    *
    * @example
    * const c = await store.modelconversation.create(42, { provider: 'openrouter', model: 'openai/gpt-5' });
@@ -28,6 +29,10 @@ export default function create(provider) {
     if (!providerName) throw new Error('Provider required');
     const model = typeof input.model === 'string' ? input.model.trim() : '';
     if (!model) throw new Error('Model required');
+    const startedBy = input.started_by ?? null;
+    if (startedBy !== null && (!Number.isInteger(startedBy) || startedBy <= 0)) {
+      throw new Error('Invalid started_by');
+    }
 
     const runner = makeRunner(provider, tx);
     const { companyuserId } = await access(googleAuthId, runner);
@@ -36,6 +41,7 @@ export default function create(provider) {
       companyuserId,
       provider: providerName,
       model,
+      startedBy,
     });
     return shape(result.rows[0]);
   };

src/store/modelconversation/delete.js

@@ -9,7 +9,8 @@ export default function del(provider) {
     provider?.dialect === 'sqlite3' ? SQLITE_DELETE : MSSQL_DELETE;
 
   /**
-   * Deletes a model conversation by ID for the user in the selected company.
+   * Deletes a model conversation by ID for the user in the selected company, together with
+   * every subagent conversation below it (`started_by` chain, recursively) and their messages.
    *
    * @param {number} googleAuthId - The id of the Google auth user.
    * @param {number} conversationId - The conversation id.

src/store/modelconversation/get.js

@@ -14,7 +14,7 @@ export default function get(provider) {
    * @param {number} googleAuthId - The id of the Google auth user.
    * @param {number} conversationId - The conversation id.
    * @param {object} [tx] - Optional transaction to run within.
-   * @returns {Promise<{id: number, companyuser_id: number, provider: string, model: string, created_at: string, updated_at: string, state: string}>}
+   * @returns {Promise<{id: number, companyuser_id: number, provider: string, model: string, created_at: string, updated_at: string, state: string, started_by: number|null}>}
    * @throws {Error} 'Conversation not found'.
    */
   return async (googleAuthId, conversationId, tx) => {

src/store/modelconversation/list.js

@@ -13,7 +13,7 @@ export default function list(provider) {
    *
    * @param {number} googleAuthId - The id of the Google auth user.
    * @param {object} [tx] - Optional transaction to run within.
-   * @returns {Promise<Array<{id: number, companyuser_id: number, provider: string, model: string, created_at: string, updated_at: string, state: string}>>}
+   * @returns {Promise<Array<{id: number, companyuser_id: number, provider: string, model: string, created_at: string, updated_at: string, state: string, started_by: number|null, first_user_message: string|null}>>} `started_by` is the originating conversation id for subagent conversations (null otherwise), so clients can build a tree. `first_user_message` is the stored `message` payload of the conversation's first `user` message (null if none yet).
    *
    * @example
    * const conversations = await store.modelconversation.list(42);
@@ -22,6 +22,9 @@ export default function list(provider) {
     const runner = makeRunner(provider, tx);
     const { companyuserId } = await access(googleAuthId, runner);
     const result = await runner.query(sql, { companyuserId });
-    return result.rows.map(shape);
+    return result.rows.map((row) => ({
+      ...shape(row),
+      first_user_message: row.first_user_message ?? null,
+    }));
   };
 }

src/store/modelconversation/setState.js

@@ -15,7 +15,7 @@ export default function setState(provider) {
    * @param {number} conversationId - The conversation id.
    * @param {string} state - The new state ('idle' | 'busy').
    * @param {object} [tx] - Optional transaction to run within.
-   * @returns {Promise<{id: number, companyuser_id: number, provider: string, model: string, created_at: string, updated_at: string, state: string}>}
+   * @returns {Promise<{id: number, companyuser_id: number, provider: string, model: string, created_at: string, updated_at: string, state: string, started_by: number|null}>}
    * @throws {Error} 'Invalid state' or 'Conversation not found'.
    */
   return async (googleAuthId, conversationId, state, tx) => {

src/store/modelconversation/shape.js

@@ -7,5 +7,6 @@ export default function shape(row) {
     created_at: row.created_at ?? row.createdAt,
     updated_at: row.updated_at ?? row.updatedAt,
     state: row.state,
+    started_by: row.started_by ?? row.startedBy ?? null,
   };
 }