feat(brainstorm): divergent style

engines/claude.json

@@ -53,6 +53,8 @@
   "companion": {
     "protocol": "stream-json",
     "serverCmd": ["--print", "--verbose", "--input-format", "stream-json", "--output-format", "stream-json", "--max-turns", "1"],
+    "systemPromptFlag": "--system-prompt",
+    "textOnlyArgs": ["--tools", ""],
     "features": {
       "threadResume": false,
       "nativeReview": false,

packages/adapter-cli/src/generated/adapter-helpers.ts

@@ -1,6 +1,6 @@
 // @generated by kern v4.5.0 — DO NOT EDIT. Source: src/kern/adapter-helpers.kern
 
-// @kern-source: adapter-helpers:520
+// @kern-source: adapter-helpers:525
 
 import type { EngineDefinition, EngineMode, EngineModeConfig, ImageAttachment, EngineIsolationPlan } from '@kernlang/agon-core';
 
@@ -324,12 +324,13 @@ export function resolveAgentArgs(engine: EngineDefinition, permissionLevel: 'ful
 }
 
 /**
- * Extract text content from Claude stream-json NDJSON output. Returns plain text with system/hook messages removed.
+ * Extract text content from Claude stream-json NDJSON output. The final result event is the authoritative answer when present — concatenating it with the assistant text blocks duplicates the answer, and in multi-turn tool runs the early assistant texts are tool preambles ('I'll quickly verify...'), not the answer. Assistant texts remain the fallback for streams the result never closed (timeout kill, max-tokens is_error).
  */
 // @kern-source: adapter-helpers:297
 export function stripStreamJson(stdout: string): string {
   const lines = stdout.split('\n');
-  const textParts: string[] = [];
+  const assistantParts: string[] = [];
+  let resultText = '';
 
   for (const line of lines) {
     const trimmed = line.trim();
@@ -339,27 +340,31 @@ export function stripStreamJson(stdout: string): string {
       // assistant message → extract text blocks
       if (msg.type === 'assistant' && msg.message?.content) {
         for (const block of msg.message.content) {
-          if (block.type === 'text' && block.text) textParts.push(block.text);
+          if (block.type === 'text' && block.text) assistantParts.push(block.text);
         }
       }
-      // result → extract result text
+      // result → the final answer (last one wins if several appear). Only a
+      // string result is authoritative; non-string payloads (objects) keep
+      // the old stringify-into-parts behavior instead of masking the
+      // assistant text with '{}'.
       else if (msg.type === 'result' && msg.result && !msg.is_error) {
-        textParts.push(typeof msg.result === 'string' ? msg.result : JSON.stringify(msg.result));
+        if (typeof msg.result === 'string') resultText = msg.result;
+        else assistantParts.push(JSON.stringify(msg.result));
       }
       // system, hook, etc. → skip
     } catch {
       // Not JSON — raw text from non-Claude engines, keep as-is
-      textParts.push(trimmed);
+      assistantParts.push(trimmed);
     }
   }
 
-  return textParts.join('\n');
+  return resultText.trim() ? resultText : assistantParts.join('\n');
 }
 
 /**
  * Check if engine exec mode outputs stream-json NDJSON.
  */
-// @kern-source: adapter-helpers:328
+// @kern-source: adapter-helpers:333
 export function usesStreamJson(engine: EngineDefinition): boolean {
   const args = engine.exec?.args ?? [];
   return args.includes('stream-json') || args.some((a: string) => a === '--output-format' && args[args.indexOf(a) + 1] === 'stream-json');
@@ -368,12 +373,12 @@ export function usesStreamJson(engine: EngineDefinition): boolean {
 /**
  * Only Codex-style JSON-RPC app-server is reliable for one-shot forge agent dispatch. Claude stream-json and Gemini ACP are reliable as persistent Cesar sessions, but the one-shot companion wrapper can hang or return empty, so forge should use their direct non-interactive CLI agent commands.
  */
-// @kern-source: adapter-helpers:334
+// @kern-source: adapter-helpers:339
 export function shouldUseCompanionForAgent(engine: EngineDefinition): boolean {
   return engine.companion?.protocol === 'jsonrpc';
 }
 
-// @kern-source: adapter-helpers:339
+// @kern-source: adapter-helpers:344
 export function checkEnvVars(engine: EngineDefinition): string|null {
   if (!engine.env) return null;
   for (const [envVar, config] of Object.entries(engine.env)) {
@@ -387,7 +392,7 @@ export function checkEnvVars(engine: EngineDefinition): string|null {
 /**
  * Drive `claude` via the kern-engines PTY subscription TUI? DEFAULT is now NO — claude dispatches via `claude --print` (-p), which Anthropic no longer meters under the subscription and is far more reliable than scraping the TUI. Opt back INTO the PTY brain with AGON_CLAUDE_PTY=1 / `agon config claudeBackend pty` (single source of truth: claudeBrainUsesPty). Claude is identified by id OR binary === 'claude' so this agrees with the persistent-session and cesar/session gates. cwd (when known) lets a project-local config override apply.
  */
-// @kern-source: adapter-helpers:350
+// @kern-source: adapter-helpers:355
 export function shouldUseClaudePty(engine: EngineDefinition, cwd?: string): boolean {
   if (engine.id !== 'claude' && engine.binary !== 'claude') {
     return false;
@@ -398,7 +403,7 @@ export function shouldUseClaudePty(engine: EngineDefinition, cwd?: string): bool
 /**
  * When a caller passed a systemPrompt, prepend it to the prompt with the same [System Instructions]/[User Message] framing the legacy non-flag CLI path uses. Claude's TUI has no --system-prompt equivalent we can apply through stdin, so this is the honest way to keep forge/tribunal/brainstorm system instructions intact on the pty path.
  */
-// @kern-source: adapter-helpers:357
+// @kern-source: adapter-helpers:362
 export function composeClaudePtyPrompt(prompt: string, systemPrompt?: string): string {
   if (!systemPrompt) return prompt;
   return `[System Instructions]\n${systemPrompt}\n\n[User Message]\n${prompt}`;
@@ -407,7 +412,7 @@ export function composeClaudePtyPrompt(prompt: string, systemPrompt?: string): s
 /**
  * Structured answer-channel transport for ONE-SHOT claude exec dispatch (council/forge/brainstorm/tribunal/synthesis members), bypassing the flaky TUI scrape. ON by default ('file' — claude writes its answer via its native Write tool to a temp file we read as authoritative). AGON_CLAUDE_ANSWER_CHANNEL: 'off'/'0'/'false' → off (raw scrape, for debugging); 'mcp' → the DeliverAnswer MCP variant (reserved); anything else (incl. unset) → 'file'. Never worse than the scrape — we fall back to it when claude doesn't deliver.
  */
-// @kern-source: adapter-helpers:364
+// @kern-source: adapter-helpers:369
 export function answerChannelMode(): string {
   const v = (process.env.AGON_CLAUDE_ANSWER_CHANNEL || '').trim().toLowerCase();
   if (v === 'off' || v === '0' || v === 'false') return 'off';
@@ -418,7 +423,7 @@ export function answerChannelMode(): string {
 /**
  * Whether the file answer-channel applies for a given one-shot dispatch mode. TRUE for both exec (council/forge/brainstorm/tribunal/synthesis members) AND agent (forge one-shot agent dispatch) — both lose long-form output to TUI scrape corruption and benefit from the authoritative file. Gated by answerChannelMode()==='file'. Defaults mode to 'exec'.
  */
-// @kern-source: adapter-helpers:373
+// @kern-source: adapter-helpers:378
 export function useFileChannelForMode(mode?: 'exec'|'agent'): boolean {
   const m = mode ?? 'exec';
   return (m === 'exec' || m === 'agent') && answerChannelMode() === 'file';
@@ -427,15 +432,15 @@ export function useFileChannelForMode(mode?: 'exec'|'agent'): boolean {
 /**
  * Appended to a one-shot claude prompt under file answer-channel mode: instruct claude to deliver its COMPLETE answer by writing it (markdown only, no commentary) to answerFile with its native Write tool. This is what makes the answer arrive as a clean file instead of a scraped TUI frame.
  */
-// @kern-source: adapter-helpers:380
+// @kern-source: adapter-helpers:385
 export function fileChannelInstruction(answerFile: string): string {
   return `\n\n---\n[ANSWER DELIVERY — REQUIRED] After composing your COMPLETE final answer, use your Write tool to write that answer — markdown only, no preamble, no commentary, nothing but the answer itself — to this exact file path:\n${answerFile}\nThat file is the ONLY channel by which your answer is captured. Write it exactly once, at the very end. Do NOT skip it.`;
 }
 
 /**
  * Read the authoritative answer a one-shot claude wrote to the channel file. Returns '' when the file is absent/empty (caller falls back to the scrape). Accepts raw markdown (file mode, native Write) OR a {text} JSON envelope (mcp mode, DeliverAnswer) transparently.
  */
-// @kern-source: adapter-helpers:386
+// @kern-source: adapter-helpers:391
 export function readAnswerChannelFile(answerFile: string): string {
   try {
     if (!existsSync(answerFile)) return '';
@@ -455,7 +460,7 @@ export function readAnswerChannelFile(answerFile: string): string {
 /**
  * Create a fresh temp dir + answer file for file-mode delivery and append the delivery instruction to the composed prompt. Returns the augmented prompt, the answer file path to read after the turn, and the dir to remove afterwards.
  */
-// @kern-source: adapter-helpers:404
+// @kern-source: adapter-helpers:409
 export function setupFileAnswerChannel(composed: string): { prompt:string, answerFile:string, dir:string } {
   const dir = mkdtempSync(join(tmpdir(), 'agon-ac-'));
   const answerFile = join(dir, 'answer.md');
@@ -465,7 +470,7 @@ export function setupFileAnswerChannel(composed: string): { prompt:string, answe
 /**
  * Drive interactive `claude` under a pty so the subscription billing path is used. Lazy-imports @kernlang/agon-engines — runs a python3 daemon (kern_engines.cli.daemon) over stdio JSON-RPC, no native node deps. cwd is plumbed through so worktree dispatches land in the right repo; systemPrompt is prepended to the prompt; extraArgv (model/effort launch flags) is forwarded to the engine exec. When AGON_CLAUDE_ANSWER_CHANNEL=file and mode is exec OR agent, claude is asked to Write its answer to a temp file we read as the AUTHORITATIVE result (clean — no TUI scrape), falling back to the scrape if the file is absent. Never throws — returns unavailable:true on any unexpected failure so kern callers can fall through to legacy paths with a simple !result.unavailable check.
  */
-// @kern-source: adapter-helpers:412
+// @kern-source: adapter-helpers:417
 export async function runClaudePtyDispatch(prompt: string, timeoutSec: number, signal?: AbortSignal, mode?: 'exec'|'agent', cwd?: string, systemPrompt?: string, env?: Record<string,string>, extraArgv?: string[]): Promise<{exitCode:number,stdout:string,stderr:string,durationMs:number,timedOut:boolean,unavailable?:boolean}> {
   const start = Date.now();
   try {

packages/adapter-cli/src/generated/adapter.ts

@@ -90,7 +90,7 @@ export class CliAdapter implements EngineAdapter {
     }
     // Try companion protocol (JSONRPC app-server) first — faster, more stable
     if (options.engine.companion) {
-      const companionResult = await companionDispatch({ config: options.engine.companion, binaryPath: binaryPath, prompt: options.prompt, cwd: options.cwd, timeout: options.timeout, mode: (options.mode === 'agent') ? 'agent' : ((options.mode === 'review') ? 'review' : 'exec'), model: resolveModel(options.engine, options.cwd) ?? undefined, signal: options.signal, systemPrompt: options.systemPrompt, env: iso.env });
+      const companionResult = await companionDispatch({ config: options.engine.companion, binaryPath: binaryPath, prompt: options.prompt, cwd: options.cwd, timeout: options.timeout, mode: (options.mode === 'agent') ? 'agent' : ((options.mode === 'review') ? 'review' : 'exec'), model: resolveModel(options.engine, options.cwd) ?? undefined, signal: options.signal, systemPrompt: options.systemPrompt, textOnly: options.textOnly, env: iso.env });
       // Exit code 2 = companion not available, fall through to CLI spawn
       // Also fall through if companion returned empty output (stream-json capture failure)
       if (companionResult.exitCode !== 2 && companionResult.stdout.trim()) {

packages/adapter-cli/src/kern/adapter-helpers.kern

@@ -295,10 +295,11 @@ fn name=resolveAgentArgs params="engine:EngineDefinition, permissionLevel:'full'
   >>>
 
 fn name=stripStreamJson params="stdout:string" returns=string
-  doc "Extract text content from Claude stream-json NDJSON output. Returns plain text with system/hook messages removed."
+  doc "Extract text content from Claude stream-json NDJSON output. The final result event is the authoritative answer when present — concatenating it with the assistant text blocks duplicates the answer, and in multi-turn tool runs the early assistant texts are tool preambles ('I'll quickly verify...'), not the answer. Assistant texts remain the fallback for streams the result never closed (timeout kill, max-tokens is_error)."
   handler <<<
     const lines = stdout.split('\n');
-    const textParts: string[] = [];
+    const assistantParts: string[] = [];
+    let resultText = '';
 
     for (const line of lines) {
       const trimmed = line.trim();
@@ -308,21 +309,25 @@ fn name=stripStreamJson params="stdout:string" returns=string
         // assistant message → extract text blocks
         if (msg.type === 'assistant' && msg.message?.content) {
           for (const block of msg.message.content) {
-            if (block.type === 'text' && block.text) textParts.push(block.text);
+            if (block.type === 'text' && block.text) assistantParts.push(block.text);
           }
         }
-        // result → extract result text
+        // result → the final answer (last one wins if several appear). Only a
+        // string result is authoritative; non-string payloads (objects) keep
+        // the old stringify-into-parts behavior instead of masking the
+        // assistant text with '{}'.
         else if (msg.type === 'result' && msg.result && !msg.is_error) {
-          textParts.push(typeof msg.result === 'string' ? msg.result : JSON.stringify(msg.result));
+          if (typeof msg.result === 'string') resultText = msg.result;
+          else assistantParts.push(JSON.stringify(msg.result));
         }
         // system, hook, etc. → skip
       } catch {
         // Not JSON — raw text from non-Claude engines, keep as-is
-        textParts.push(trimmed);
+        assistantParts.push(trimmed);
       }
     }
 
-    return textParts.join('\n');
+    return resultText.trim() ? resultText : assistantParts.join('\n');
   >>>
 
 fn name=usesStreamJson params="engine:EngineDefinition" returns=boolean

packages/adapter-cli/src/kern/adapter.kern

@@ -75,7 +75,7 @@ service name=CliAdapter implements=EngineAdapter
           return value="ptyResult"
       comment raw="// Try companion protocol (JSONRPC app-server) first — faster, more stable"
       if cond="options.engine.companion"
-        let name=companionResult value="await companionDispatch({ config: options.engine.companion, binaryPath, prompt: options.prompt, cwd: options.cwd, timeout: options.timeout, mode: options.mode === 'agent' ? 'agent' : options.mode === 'review' ? 'review' : 'exec', model: resolveModel(options.engine, options.cwd) ?? undefined, signal: options.signal, systemPrompt: options.systemPrompt, env: iso.env, })"
+        let name=companionResult value="await companionDispatch({ config: options.engine.companion, binaryPath, prompt: options.prompt, cwd: options.cwd, timeout: options.timeout, mode: options.mode === 'agent' ? 'agent' : options.mode === 'review' ? 'review' : 'exec', model: resolveModel(options.engine, options.cwd) ?? undefined, signal: options.signal, systemPrompt: options.systemPrompt, textOnly: options.textOnly, env: iso.env, })"
         comment raw="// Exit code 2 = companion not available, fall through to CLI spawn"
         comment raw="// Also fall through if companion returned empty output (stream-json capture failure)"
         if cond="companionResult.exitCode !== 2 && companionResult.stdout.trim()"

packages/cli/src/commands/brainstorm.ts

@@ -32,6 +32,11 @@ export const brainstormCommand = defineCommand({
       description: 'Timeout in seconds',
       default: '120',
     },
+    style: {
+      type: 'string',
+      description: "'divergent' (default: seats get distinct stances, synthesis keeps 2-3 directions) or 'grounded' (convergent, file-path-anchored single answer)",
+      default: 'divergent',
+    },
     label: {
       type: 'string',
       description: 'Human-readable suffix baked into the run dir name (orchestrators: distinguish parallel runs without grep).',
@@ -53,6 +58,10 @@ export const brainstormCommand = defineCommand({
       ? args.engines.split(',').map((s) => s.trim())
       : filterDefaultOrchestrationEngines(registry.activeIds(config));
 
+    if (args.style !== 'divergent' && args.style !== 'grounded') {
+      throw new Error(`Unknown --style "${args.style}" — use 'divergent' or 'grounded'.`);
+    }
+
     if (args.quiet) process.env.AGON_QUIET = '1';
     const startedAt = new Date().toISOString();
     const { path: outputDir } = createRunDir({
@@ -64,6 +73,7 @@ export const brainstormCommand = defineCommand({
     if (!quiet) {
       header(`Brainstorm: ${args.question}`);
       info(`Engines: ${available.join(', ')}`);
+      info(`Style: ${args.style}`);
     }
 
     const seatState = new Map<string, { ok: boolean; detail: string }>();
@@ -72,6 +82,7 @@ export const brainstormCommand = defineCommand({
       result = await runBrainstorm({
         question: args.question,
         engines: available,
+        style: args.style,
         registry,
         adapter,
         timeout: parseInt(args.timeout, 10),