Fix --no-skills flag not preventing skills from loading

The --no-skills flag set options.skills = [] in main.ts, but the
interactive mode UI would rediscover skills anyway because it called
loadSkills() directly instead of using the already-loaded skills.

Changes:
- Add AgentSession.skills and AgentSession.skillWarnings properties
- discoverSkills() now returns { skills, warnings } instead of Skill[]
- Interactive mode uses session.skills instead of calling loadSkills()
- Update SDK docs and examples for new return type

Fixes #577

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

@@ -50,6 +50,7 @@ import type { ModelRegistry } from "./model-registry.js";
 import { expandPromptTemplate, type PromptTemplate } from "./prompt-templates.js";
 import type { BranchSummaryEntry, CompactionEntry, NewSessionOptions, SessionManager } from "./session-manager.js";
 import type { SettingsManager, SkillsSettings } from "./settings-manager.js";
+import type { Skill, SkillWarning } from "./skills.js";
 import type { BashOperations } from "./tools/bash.js";
 
 /** Session-specific events that extend the core AgentEvent */
@@ -77,6 +78,10 @@ export interface AgentSessionConfig {
 	promptTemplates?: PromptTemplate[];
 	/** Extension runner (created in sdk.ts with wrapped tools) */
 	extensionRunner?: ExtensionRunner;
+	/** Loaded skills (already discovered by SDK) */
+	skills?: Skill[];
+	/** Skill loading warnings (already captured by SDK) */
+	skillWarnings?: SkillWarning[];
 	skillsSettings?: Required<SkillsSettings>;
 	/** Model registry for API key resolution and model discovery */
 	modelRegistry: ModelRegistry;
@@ -177,6 +182,8 @@ export class AgentSession {
 	private _extensionRunner: ExtensionRunner | undefined = undefined;
 	private _turnIndex = 0;
 
+	private _skills: Skill[];
+	private _skillWarnings: SkillWarning[];
 	private _skillsSettings: Required<SkillsSettings> | undefined;
 
 	// Model registry for API key resolution
@@ -198,6 +205,8 @@ export class AgentSession {
 		this._scopedModels = config.scopedModels ?? [];
 		this._promptTemplates = config.promptTemplates ?? [];
 		this._extensionRunner = config.extensionRunner;
+		this._skills = config.skills ?? [];
+		this._skillWarnings = config.skillWarnings ?? [];
 		this._skillsSettings = config.skillsSettings;
 		this._modelRegistry = config.modelRegistry;
 		this._toolRegistry = config.toolRegistry ?? new Map();
@@ -870,6 +879,16 @@ export class AgentSession {
 		return this._skillsSettings;
 	}
 
+	/** Skills loaded by SDK (empty if --no-skills or skills: [] was passed) */
+	get skills(): readonly Skill[] {
+		return this._skills;
+	}
+
+	/** Skill loading warnings captured by SDK */
+	get skillWarnings(): readonly SkillWarning[] {
+		return this._skillWarnings;
+	}
+
 	/**
 	 * Abort current operation and wait for agent to become idle.
 	 */