feat: add --continue flag to `ao start` for orchestrator conversation continuity

When the orchestrator needs a fresh system prompt (e.g. CLAUDE.local.md was
updated), `ao start --continue` kills the existing session and respawns with
`claude --continue`, preserving conversation history while reloading prompts.

Changes:
- Add `continue` option to AgentLaunchConfig and OrchestratorSpawnConfig
- Claude Code agent plugin passes --continue to CLI when set
- Session manager forwards continue option to agent launch config
- `ao start --continue` kills existing orchestrator, respawns with continue flag
- Other agent plugins unaffected (optional field, backwards-compatible)

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

packages/cli/src/commands/start.ts

@@ -124,6 +124,10 @@ export function registerStart(program: Command): void {
     .option("--no-dashboard", "Skip starting the dashboard server")
     .option("--no-orchestrator", "Skip starting the orchestrator agent")
     .option("--rebuild", "Clean and rebuild dashboard before starting")
+    .option(
+      "--continue",
+      "Continue the most recent orchestrator conversation (kills existing session first, preserves conversation history with fresh system prompt)",
+    )
     .action(
       async (
         projectArg?: string,
@@ -131,6 +135,7 @@ export function registerStart(program: Command): void {
           dashboard?: boolean;
           orchestrator?: boolean;
           rebuild?: boolean;
+          continue?: boolean;
         },
       ) => {
         try {
@@ -180,6 +185,15 @@ export function registerStart(program: Command): void {
             const existing = await sm.get(sessionId);
             exists = existing !== null && existing.status !== "killed";
 
+            // --continue: kill existing session so claude --continue picks up
+            // the most recent conversation with a fresh system prompt
+            if (opts?.continue && exists) {
+              spinner.start("Killing existing orchestrator session for --continue");
+              await sm.kill(sessionId);
+              spinner.succeed("Existing orchestrator session killed");
+              exists = false;
+            }
+
             if (exists) {
               if (existing?.runtimeHandle?.id) {
                 tmuxTarget = existing.runtimeHandle.id;
@@ -191,14 +205,26 @@ export function registerStart(program: Command): void {
               );
             } else {
               try {
-                spinner.start("Creating orchestrator session");
+                spinner.start(
+                  opts?.continue
+                    ? "Continuing orchestrator session"
+                    : "Creating orchestrator session",
+                );
                 const systemPrompt = generateOrchestratorPrompt({ config, projectId, project });
 
-                const session = await sm.spawnOrchestrator({ projectId, systemPrompt });
+                const session = await sm.spawnOrchestrator({
+                  projectId,
+                  systemPrompt,
+                  continue: opts?.continue,
+                });
                 if (session.runtimeHandle?.id) {
                   tmuxTarget = session.runtimeHandle.id;
                 }
-                spinner.succeed("Orchestrator session created");
+                spinner.succeed(
+                  opts?.continue
+                    ? "Orchestrator session continued"
+                    : "Orchestrator session created",
+                );
               } catch (err) {
                 spinner.fail("Orchestrator setup failed");
                 // Cleanup dashboard if orchestrator setup fails

packages/core/src/session-manager.ts

@@ -641,6 +641,7 @@ export function createSessionManager(deps: SessionManagerDeps): SessionManager {
       permissions: "skip" as const,
       model: project.agentConfig?.model,
       systemPromptFile,
+      continue: orchestratorConfig.continue,
     };
 
     const launchCommand = plugins.agent.getLaunchCommand(agentLaunchConfig);

packages/core/src/types.ts

@@ -184,6 +184,12 @@ export interface SessionSpawnConfig {
 export interface OrchestratorSpawnConfig {
   projectId: string;
   systemPrompt?: string;
+  /**
+   * Continue the most recent conversation in the project directory.
+   * When true, the agent is launched with --continue (or equivalent),
+   * preserving conversation history while loading fresh system prompts.
+   */
+  continue?: boolean;
 }
 
 // =============================================================================
@@ -352,6 +358,13 @@ export interface AgentLaunchConfig {
    * - Codex/Aider: similar shell substitution
    */
   systemPromptFile?: string;
+  /**
+   * Continue the most recent conversation in the project directory.
+   * Loads fresh system prompt while preserving conversation history.
+   * - Claude Code: --continue flag
+   * - Other agents: ignored if not supported
+   */
+  continue?: boolean;
 }
 
 export interface WorkspaceHooksConfig {

packages/plugins/agent-claude-code/src/index.test.ts

@@ -203,6 +203,24 @@ describe("getLaunchCommand", () => {
     expect(cmd).not.toMatch(/\s-p\s/);
     expect(cmd).not.toContain("Do the task");
   });
+
+  it("includes --continue when continue=true", () => {
+    const cmd = agent.getLaunchCommand(makeLaunchConfig({ continue: true }));
+    expect(cmd).toContain("--continue");
+    expect(cmd).toBe("claude --continue");
+  });
+
+  it("combines --continue with other flags", () => {
+    const cmd = agent.getLaunchCommand(
+      makeLaunchConfig({ continue: true, permissions: "skip", model: "opus" }),
+    );
+    expect(cmd).toBe("claude --continue --dangerously-skip-permissions --model 'opus'");
+  });
+
+  it("omits --continue when continue is not set", () => {
+    const cmd = agent.getLaunchCommand(makeLaunchConfig());
+    expect(cmd).not.toContain("--continue");
+  });
 });
 
 // =========================================================================

packages/plugins/agent-claude-code/src/index.ts

@@ -635,6 +635,10 @@ function createClaudeCodeAgent(): Agent {
       // This command must be safe for both shell and execFile contexts.
       const parts: string[] = ["claude"];
 
+      if (config.continue) {
+        parts.push("--continue");
+      }
+
       if (config.permissions === "skip") {
         parts.push("--dangerously-skip-permissions");
       }