Allow configuring mach6 skill agent models via settings with TUI ranking

packages/agent/src/agent.ts

@@ -128,7 +128,7 @@ export interface AgentOptions {
 export class Agent {
 	private _state: AgentState = {
 		systemPrompt: "",
-		model: getModel("google", "gemini-2.5-flash-lite-preview-06-17"),
+		model: getModel("google", "gemini-2.5-flash-lite"),
 		thinkingLevel: "off",
 		tools: [],
 		messages: [],

packages/coding-agent/docs/mach6-models.md

@@ -0,0 +1,61 @@
+# Mach6 Model Settings
+
+Configure per-agent model overrides for mach6 skill agents via settings.
+
+## What it does
+
+The `agentModels.models` setting lets you override the default model used by each subagent type (e.g., Explore, Sandbox) without modifying the agent definition files. You can specify an ordered fallback list — the first available model is used.
+
+## Configuration
+
+Add to your `~/.dreb/settings.json`:
+
+```json
+{
+  "agentModels": {
+    "models": {
+      "Explore": ["openai/gpt-4o", "anthropic/claude-sonnet-4-20250514"],
+      "Sandbox": ["anthropic/claude-haiku-3-20250422"]
+    }
+  }
+}
+```
+
+Each key is an agent type name, and the value is an ordered list of model IDs (in `provider/model` format).
+
+## Resolution Order
+
+When a subagent is launched, models are resolved in this priority:
+
+1. **Per-invocation `model` override** — highest priority, set explicitly in the subagent tool call
+2. **`agentModels.models` setting** — from your settings.json, per agent type
+3. **Agent definition `model` field** — from the `.md` agent file's frontmatter
+
+If the mach6 models list is empty or undefined for a given agent, it falls through to the agent definition's model.
+
+## TUI Usage
+
+Open `/settings` and scroll to the ⚡ items. Each discovered agent type gets its own entry where you can:
+
+- **Reorder** models (move up/down to set priority)
+- **Add** new models from the available model list
+- **Remove** models from the fallback list
+
+Changes are saved to your global settings immediately.
+
+## Example
+
+```json
+{
+  "agentModels": {
+    "models": {
+      "Explore": [
+        "openai/gpt-4o-mini",
+        "anthropic/claude-haiku-3-20250422"
+      ]
+    }
+  }
+}
+```
+
+This configures the Explore agent to prefer `gpt-4o-mini`, falling back to `claude-haiku` if the first isn't available. All other agents use their default models.

packages/coding-agent/src/core/agent-session.ts

@@ -2761,6 +2761,7 @@ export class AgentSession {
 						parentProvider: () => this.model?.provider,
 						parentModel: () => this.model?.id,
 						modelRegistry: this._modelRegistry,
+						getAgentModelsForAgent: (name: string) => this.settingsManager?.getAgentModelsForAgent(name),
 						onBackgroundStart: (agentId, agentType, taskSummary) => {
 							this._emit({ type: "background_agent_start", agentId, agentType, taskSummary });
 						},

packages/coding-agent/src/core/settings-manager.ts

@@ -44,6 +44,10 @@ export interface MarkdownSettings {
 	codeBlockIndent?: string; // default: "  "
 }
 
+export interface AgentModelsSettings {
+	models?: Record<string, string[]>;
+}
+
 export type TransportSetting = Transport;
 
 /**
@@ -99,6 +103,7 @@ export interface Settings {
 	forbiddenCommands?: string[]; // Regex patterns for commands blocked by the forbidden-commands guard
 	sensitiveFilePaths?: string[]; // Additional glob patterns for sensitive file paths blocked by the read/bash guard
 	secretOutputPatterns?: { name: string; pattern: string }[]; // Additional regex patterns for secret scrubbing in tool output
+	agentModels?: AgentModelsSettings;
 	dream?: {
 		archivePath?: string; // Custom archive location for dream backups (default: ~/.dreb/memory-archive/)
 	};
@@ -972,4 +977,33 @@ export class SettingsManager {
 		this.markModified("dream", "archivePath");
 		this.save();
 	}
+
+	getAgentModels(): Record<string, string[]> {
+		return this.settings.agentModels?.models ? { ...this.settings.agentModels.models } : {};
+	}
+
+	getAgentModelsForAgent(agentName: string): string[] | undefined {
+		const models = this.settings.agentModels?.models?.[agentName];
+		return models && models.length > 0 ? [...models] : undefined;
+	}
+
+	setAgentModelsForAgent(agentName: string, models: string[]): void {
+		if (!this.globalSettings.agentModels) {
+			this.globalSettings.agentModels = {};
+		}
+		if (!this.globalSettings.agentModels.models) {
+			this.globalSettings.agentModels.models = {};
+		}
+		this.globalSettings.agentModels.models[agentName] = [...models];
+		this.markModified("agentModels", "models");
+		this.save();
+	}
+
+	removeAgentModelsForAgent(agentName: string): void {
+		if (this.globalSettings.agentModels?.models) {
+			delete this.globalSettings.agentModels.models[agentName];
+			this.markModified("agentModels", "models");
+			this.save();
+		}
+	}
 }

packages/coding-agent/src/core/tools/subagent.ts

@@ -88,7 +88,7 @@ export function parseAgentFrontmatter(
 	};
 }
 
-function discoverAgentTypes(cwd: string): Map<string, AgentTypeConfig> {
+export function discoverAgentTypes(cwd: string): Map<string, AgentTypeConfig> {
 	const agents = new Map<string, AgentTypeConfig>();
 
 	// Package-bundled agents (shipped with dreb — the canonical source of truth for built-in agents)
@@ -819,6 +819,7 @@ export async function executeSingle(
 	registry?: ModelRegistry,
 	sessionDir?: string,
 	parentModel?: string,
+	agentModels?: string[],
 ): Promise<SubagentResult> {
 	const name = agentName || DEFAULT_AGENT;
 	const config = agents.get(name);
@@ -843,9 +844,9 @@ export async function executeSingle(
 			errorMessage: `Task prompt too long (${task.length} chars, max ${MAX_TASK_LENGTH}). Shorten the prompt.`,
 		};
 	}
-	// Per-invocation model override takes precedence over agent definition model.
-	// Override is always a single string; agent config may be a string or fallback list.
-	const modelSpec = modelOverride || config.model;
+	// Per-invocation model override takes precedence over agent settings, which take precedence over agent definition model.
+	// Override is always a single string; agentModels and agent config may be arrays.
+	const modelSpec = modelOverride || (agentModels && agentModels.length > 0 ? agentModels : undefined) || config.model;
 	let effectiveConfig: AgentTypeConfig = modelOverride ? { ...config, model: modelOverride } : config;
 	let resolvedProvider = parentProvider;
 	let warning: string | undefined;
@@ -878,13 +879,10 @@ export async function executeSingle(
 		warning = resolved.warning;
 	}
 
-	onProgress?.(`Running ${name} agent...`);
+	const usedModel = effectiveConfig.model?.toString();
+	onProgress?.(`Running ${name} agent${usedModel ? ` (${usedModel})` : ""}...`);
 	const result = await spawnSubagent(effectiveConfig, task, cwd, signal, onProgress, resolvedProvider, sessionDir);
-	result.output = prependModelFallbackSummary(
-		result.output,
-		skippedModels,
-		result.model ?? effectiveConfig.model?.toString(),
-	);
+	result.output = prependModelFallbackSummary(result.output, skippedModels, result.model ?? usedModel);
 	if (warning) {
 		result.output = `[WARNING: ${warning}]\n\n${result.output}`;
 	}
@@ -903,6 +901,7 @@ async function executeChain(
 	defaultAgent?: string,
 	defaultModel?: string,
 	parentModel?: string,
+	getAgentModelsForAgentFn?: (name: string) => string[] | undefined,
 ): Promise<SubagentResult[]> {
 	const results: SubagentResult[] = [];
 	let previousOutput = "";
@@ -941,6 +940,8 @@ async function executeChain(
 
 		// Each chain step gets its own session subdirectory
 		const stepSessionDir = sessionBaseDir ? join(sessionBaseDir, `step-${i + 1}`) : undefined;
+		const stepAgentName = step.agent || defaultAgent || DEFAULT_AGENT;
+		const stepMach6Models = getAgentModelsForAgentFn?.(stepAgentName);
 		const result = await executeSingle(
 			agents,
 			step.agent || defaultAgent,
@@ -953,6 +954,7 @@ async function executeChain(
 			registry,
 			stepSessionDir,
 			parentModel,
+			stepMach6Models,
 		);
 		results.push(result);
 
@@ -1032,6 +1034,8 @@ export interface SubagentToolOptions {
 	parentModel?: () => string | undefined;
 	/** Model registry for validating model names before spawning child processes. */
 	modelRegistry?: ModelRegistry;
+	/** Settings-based model override getter for mach6.models. */
+	getAgentModelsForAgent?: (agentName: string) => string[] | undefined;
 }
 
 // ---------------------------------------------------------------------------
@@ -1191,6 +1195,7 @@ export function createSubagentToolDefinition(
 	const getParentProvider = options?.parentProvider ?? (() => undefined);
 	const getParentModel = options?.parentModel ?? (() => undefined);
 	const modelRegistry = options?.modelRegistry;
+	const getAgentModelsForAgent = options?.getAgentModelsForAgent;
 
 	// Discover agents at definition time to build the prompt guidelines.
 	// This is cheap (reads .md files) and the same call happens on every execute().
@@ -1368,6 +1373,7 @@ export function createSubagentToolDefinition(
 					// Each background agent gets its own session subdirectory
 					const sessionId = generateAgentId();
 					const sessionDir = join(subagentSessionsBase, sessionId);
+					const agentModels = getAgentModelsForAgent?.(agentName || DEFAULT_AGENT);
 					return launchBackgroundLifecycle(agentName, taskLabel, (signal) =>
 						executeSingle(
 							agents,
@@ -1381,6 +1387,7 @@ export function createSubagentToolDefinition(
 							modelRegistry,
 							sessionDir,
 							getParentModel(),
+							agentModels,
 						),
 					);
 				};
@@ -1471,6 +1478,7 @@ export function createSubagentToolDefinition(
 							params.agent,
 							params.model,
 							getParentModel(),
+							getAgentModelsForAgent,
 						);
 						const resultText = results
 							.map((r, i) => `### Step ${i + 1}\n${formatSingleResult(r)}`)