feat(cue): enable cross-directory pipelines for subdirectory agents

src/__tests__/main/cue/cue-completion-chains.test.ts

@@ -27,6 +27,7 @@ vi.mock('../../../main/cue/cue-yaml-loader', () => ({
 			: { ok: false as const, reason: 'missing' as const };
 	},
 	watchCueYaml: (...args: unknown[]) => mockWatchCueYaml(args[0] as string, args[1] as () => void),
+	findAncestorCueConfigRoot: () => null,
 }));
 
 // Mock the file watcher

src/__tests__/main/cue/cue-concurrency.test.ts

@@ -26,6 +26,7 @@ vi.mock('../../../main/cue/cue-yaml-loader', () => ({
 			: { ok: false as const, reason: 'missing' as const };
 	},
 	watchCueYaml: (...args: unknown[]) => mockWatchCueYaml(args[0] as string, args[1] as () => void),
+	findAncestorCueConfigRoot: () => null,
 }));
 
 // Mock the file watcher

src/__tests__/main/cue/cue-engine.test.ts

@@ -29,6 +29,7 @@ vi.mock('../../../main/cue/cue-yaml-loader', () => ({
 	loadCueConfig: (...args: unknown[]) => mockLoadCueConfig(args[0] as string),
 	loadCueConfigDetailed: (...args: unknown[]) => mockLoadCueConfigDetailed(args[0] as string),
 	watchCueYaml: (...args: unknown[]) => mockWatchCueYaml(args[0] as string, args[1] as () => void),
+	findAncestorCueConfigRoot: () => null,
 }));
 
 // Mock the file watcher

src/__tests__/main/cue/cue-ipc-handlers.test.ts

@@ -44,6 +44,7 @@ vi.mock('../../../main/utils/ipcHandler', () => ({
 
 vi.mock('../../../main/cue/cue-yaml-loader', () => ({
 	validateCueConfig: vi.fn(),
+	findAncestorCueConfigRoot: () => null,
 }));
 
 vi.mock('../../../main/cue/config/cue-config-repository', () => ({

src/__tests__/main/cue/cue-multi-hop-chains.test.ts

@@ -25,6 +25,7 @@ vi.mock('../../../main/cue/cue-yaml-loader', () => ({
 			: { ok: false as const, reason: 'missing' as const };
 	},
 	watchCueYaml: (...args: unknown[]) => mockWatchCueYaml(args[0] as string, args[1] as () => void),
+	findAncestorCueConfigRoot: () => null,
 }));
 
 // Mock the file watcher

src/__tests__/main/cue/cue-session-lifecycle.test.ts

@@ -25,6 +25,7 @@ vi.mock('../../../main/cue/cue-yaml-loader', () => ({
 			: { ok: false as const, reason: 'missing' as const };
 	},
 	watchCueYaml: (...args: unknown[]) => mockWatchCueYaml(args[0] as string, args[1] as () => void),
+	findAncestorCueConfigRoot: () => null,
 }));
 
 // Mock the file watcher

src/__tests__/main/cue/cue-sleep-prevention.test.ts

@@ -23,6 +23,7 @@ vi.mock('../../../main/cue/cue-yaml-loader', () => ({
 			: { ok: false as const, reason: 'missing' as const };
 	},
 	watchCueYaml: (...args: unknown[]) => mockWatchCueYaml(args[0] as string, args[1] as () => void),
+	findAncestorCueConfigRoot: () => null,
 }));
 
 // Mock the file watcher

src/__tests__/main/cue/cue-sleep-wake.test.ts

@@ -49,6 +49,7 @@ vi.mock('../../../main/cue/cue-yaml-loader', () => ({
 			: { ok: false as const, reason: 'missing' as const };
 	},
 	watchCueYaml: (...args: unknown[]) => mockWatchCueYaml(args[0] as string, args[1] as () => void),
+	findAncestorCueConfigRoot: () => null,
 }));
 
 // Mock the file watcher

src/__tests__/main/cue/cue-startup.test.ts

@@ -32,6 +32,7 @@ vi.mock('../../../main/cue/cue-yaml-loader', () => ({
 			: { ok: false as const, reason: 'missing' as const };
 	},
 	watchCueYaml: (...args: unknown[]) => mockWatchCueYaml(args[0] as string, args[1] as () => void),
+	findAncestorCueConfigRoot: () => null,
 }));
 
 // Mock the file watcher

src/__tests__/main/cue/cue-yaml-loader.test.ts

@@ -31,6 +31,7 @@ vi.mock('fs', () => ({
 
 // Must import after mocks
 import {
+	findAncestorCueConfigRoot,
 	loadCueConfig,
 	loadCueConfigDetailed,
 	watchCueYaml,
@@ -1704,4 +1705,59 @@ subscriptions:
 			);
 		});
 	});
+
+	describe('findAncestorCueConfigRoot', () => {
+		it('returns null when no ancestor has a cue config', () => {
+			mockExistsSync.mockReturnValue(false);
+			const result = findAncestorCueConfigRoot('/projects/parent/child');
+			expect(result).toBeNull();
+		});
+
+		it('finds a parent directory with .maestro/cue.yaml', () => {
+			mockExistsSync.mockImplementation((p: string) => {
+				const s = String(p);
+				// Parent has .maestro/cue.yaml, child does not
+				return s === '/projects/parent/.maestro/cue.yaml';
+			});
+			const result = findAncestorCueConfigRoot('/projects/parent/child');
+			expect(result).toBe('/projects/parent');
+		});
+
+		it('does not return the input directory itself', () => {
+			// Even if the input dir has a cue.yaml, it should only look at ancestors
+			mockExistsSync.mockImplementation((p: string) => {
+				return String(p) === '/projects/parent/child/.maestro/cue.yaml';
+			});
+			const result = findAncestorCueConfigRoot('/projects/parent/child');
+			expect(result).toBeNull();
+		});
+
+		it('finds grandparent config when parent has none', () => {
+			mockExistsSync.mockImplementation((p: string) => {
+				return String(p) === '/projects/.maestro/cue.yaml';
+			});
+			const result = findAncestorCueConfigRoot('/projects/parent/child');
+			expect(result).toBe('/projects');
+		});
+
+		it('stops after depth limit even if ancestor exists further up', () => {
+			// Place cue.yaml 6 levels up — beyond the 5-level search depth
+			mockExistsSync.mockImplementation((p: string) => {
+				return String(p) === '/a/.maestro/cue.yaml';
+			});
+			const result = findAncestorCueConfigRoot('/a/b/c/d/e/f/g');
+			// /a is 6 levels up from /a/b/c/d/e/f/g — should not be found
+			expect(result).toBeNull();
+		});
+
+		it('finds ancestor with legacy maestro-cue.yaml', () => {
+			mockExistsSync.mockImplementation((p: string) => {
+				const s = String(p);
+				// No canonical, but legacy exists at parent
+				return s === '/projects/parent/maestro-cue.yaml';
+			});
+			const result = findAncestorCueConfigRoot('/projects/parent/child');
+			expect(result).toBe('/projects/parent');
+		});
+	});
 });

src/__tests__/shared/cue-path-utils.test.ts

@@ -0,0 +1,76 @@
+import { describe, it, expect } from 'vitest';
+import { computeCommonAncestorPath, isDescendantOrEqual } from '../../shared/cue-path-utils';
+
+describe('computeCommonAncestorPath', () => {
+	it('returns null for empty input', () => {
+		expect(computeCommonAncestorPath([])).toBeNull();
+	});
+
+	it('returns the path itself for a single-element array', () => {
+		expect(computeCommonAncestorPath(['/a/b/c'])).toBe('/a/b/c');
+	});
+
+	it('returns the common parent for sibling directories', () => {
+		expect(computeCommonAncestorPath(['/a/b/c', '/a/b/d'])).toBe('/a/b');
+	});
+
+	it('returns the parent when one path is a child of the other', () => {
+		expect(computeCommonAncestorPath(['/project', '/project/sub'])).toBe('/project');
+	});
+
+	it('returns the parent for deeply nested children', () => {
+		expect(computeCommonAncestorPath(['/project', '/project/sub/deep', '/project/other'])).toBe(
+			'/project'
+		);
+	});
+
+	it('returns filesystem root for completely unrelated paths', () => {
+		expect(computeCommonAncestorPath(['/a/b', '/c/d'])).toBe('/');
+	});
+
+	it('handles identical paths', () => {
+		expect(computeCommonAncestorPath(['/a/b', '/a/b'])).toBe('/a/b');
+	});
+
+	it('handles three paths with a shared prefix', () => {
+		expect(
+			computeCommonAncestorPath([
+				'/home/user/project/A',
+				'/home/user/project/B',
+				'/home/user/project/C',
+			])
+		).toBe('/home/user/project');
+	});
+});
+
+describe('isDescendantOrEqual', () => {
+	it('returns true when paths are identical', () => {
+		expect(isDescendantOrEqual('/a/b', '/a/b')).toBe(true);
+	});
+
+	it('returns true when child is a subdirectory of parent', () => {
+		expect(isDescendantOrEqual('/a/b/c', '/a/b')).toBe(true);
+	});
+
+	it('returns true for deeply nested descendant', () => {
+		expect(isDescendantOrEqual('/project/sub/deep/nested', '/project')).toBe(true);
+	});
+
+	it('returns false when child is not under parent', () => {
+		expect(isDescendantOrEqual('/a/b', '/c/d')).toBe(false);
+	});
+
+	it('returns false when parent is a subdirectory of child (reversed)', () => {
+		expect(isDescendantOrEqual('/a', '/a/b')).toBe(false);
+	});
+
+	it('returns false for partial prefix match that is not a directory boundary', () => {
+		// /a/bar is NOT a descendant of /a/b — the prefix match is not at a separator
+		expect(isDescendantOrEqual('/a/bar', '/a/b')).toBe(false);
+	});
+
+	it('handles trailing separators via normalization', () => {
+		expect(isDescendantOrEqual('/a/b/c', '/a/b/')).toBe(true);
+		expect(isDescendantOrEqual('/a/b/', '/a/b')).toBe(true);
+	});
+});

src/main/cue/cue-session-runtime-service.ts

@@ -1,10 +1,11 @@
 import type { MainLogLevel } from '../../shared/logger-types';
 import type { SessionInfo } from '../../shared/types';
-import { loadCueConfigDetailed, watchCueYaml } from './cue-yaml-loader';
+import { findAncestorCueConfigRoot, loadCueConfigDetailed, watchCueYaml } from './cue-yaml-loader';
 import { createCueEvent, type CueEvent, type CueSubscription } from './cue-types';
 import {
 	countActiveSubscriptions,
 	hasTimeBasedSubscriptions,
+	isSubscriptionParticipant,
 	type SessionState,
 } from './cue-session-state';
 import type { CueSessionRegistry } from './cue-session-registry';
@@ -97,7 +98,42 @@ export function createCueSessionRuntimeService(
 			registry.unregister(session.id);
 		}
 
-		const loadResult = loadCueConfigDetailed(session.projectRoot);
+		let loadResult = loadCueConfigDetailed(session.projectRoot);
+		let ancestorRoot: string | undefined;
+
+		// When the session's own directory has no cue.yaml, check ancestor
+		// directories. This enables sub-agents (e.g. project/Digest) to
+		// participate in pipelines defined at a parent root (e.g. project/).
+		if (!loadResult.ok && loadResult.reason === 'missing') {
+			const ancestor = findAncestorCueConfigRoot(session.projectRoot);
+			if (ancestor) {
+				const ancestorResult = loadCueConfigDetailed(ancestor);
+				if (ancestorResult.ok) {
+					// Only include subscriptions that explicitly target this
+					// session (via agent_id or fan_out). Unowned (shared)
+					// subscriptions belong to the ancestor's own session —
+					// including them here would duplicate trigger sources.
+					const targeted = ancestorResult.config.subscriptions.filter(
+						(sub) =>
+							sub.agent_id !== undefined && isSubscriptionParticipant(sub, session.id, session.name)
+					);
+
+					if (targeted.length > 0) {
+						loadResult = {
+							ok: true,
+							config: { ...ancestorResult.config, subscriptions: targeted },
+							warnings: ancestorResult.warnings,
+						};
+						ancestorRoot = ancestor;
+						deps.onLog(
+							'cue',
+							`[CUE] "${session.name}" using ancestor config from "${ancestor}" (${targeted.length} targeted subscription(s))`
+						);
+					}
+				}
+			}
+		}
+
 		if (!loadResult.ok) {
 			// Distinguish missing (silent) from parse / validation failures (loud).
 			if (loadResult.reason === 'parse-error') {
@@ -130,12 +166,15 @@ export function createCueSessionRuntimeService(
 
 		const state: SessionState = {
 			config,
+			configRoot: ancestorRoot,
 			triggerSources: [],
 			yamlWatcher: null,
 			sleepPrevented: false,
 		};
 
-		state.yamlWatcher = watchCueYaml(session.projectRoot, () => {
+		// Watch the cue.yaml at the config's actual location (ancestor or own root).
+		const watchRoot = ancestorRoot ?? session.projectRoot;
+		state.yamlWatcher = watchCueYaml(watchRoot, () => {
 			deps.onRefreshRequested(session.id, session.projectRoot);
 		});
 

src/main/cue/cue-session-state.ts

@@ -11,6 +11,10 @@ import type { CueTriggerSource } from './triggers/cue-trigger-source';
  */
 export interface SessionState {
 	config: CueConfig;
+	/** When the config was loaded from an ancestor directory (not the session's own
+	 *  projectRoot), this records the ancestor root so refreshes reload from the
+	 *  correct location. Undefined when the config lives at the session's own root. */
+	configRoot?: string;
 	triggerSources: CueTriggerSource[];
 	yamlWatcher: (() => void) | null;
 	sleepPrevented: boolean;

src/main/cue/cue-yaml-loader.ts

@@ -5,9 +5,14 @@
  * are implemented in responsibility-focused config modules.
  */
 
+import * as path from 'path';
 import * as yaml from 'js-yaml';
 import type { CueConfig } from './cue-types';
-import { readCueConfigFile, watchCueConfigFile } from './config/cue-config-repository';
+import {
+	readCueConfigFile,
+	resolveCueConfigPath,
+	watchCueConfigFile,
+} from './config/cue-config-repository';
 import { materializeCueConfig, parseCueConfigDocument } from './config/cue-config-normalizer';
 import {
 	partitionValidSubscriptions,
@@ -166,3 +171,29 @@ export function watchCueYaml(projectRoot: string, onChange: () => void): () => v
 export function validateCueConfig(config: unknown): { valid: boolean; errors: string[] } {
 	return validateCueConfigDocument(config);
 }
+
+/** Maximum number of parent directories to walk when searching for an ancestor config. */
+const ANCESTOR_SEARCH_DEPTH = 5;
+
+/**
+ * Walk parent directories from `projectRoot` looking for a cue.yaml.
+ * Returns the ancestor's project root if found, `null` otherwise.
+ *
+ * Stops at filesystem root or after {@link ANCESTOR_SEARCH_DEPTH} levels.
+ * Does NOT return `projectRoot` itself — only strict ancestors.
+ */
+export function findAncestorCueConfigRoot(projectRoot: string): string | null {
+	let current = path.resolve(projectRoot);
+
+	for (let depth = 0; depth < ANCESTOR_SEARCH_DEPTH; depth++) {
+		const parent = path.dirname(current);
+		if (parent === current) break; // reached filesystem root
+		current = parent;
+
+		if (resolveCueConfigPath(current) !== null) {
+			return current;
+		}
+	}
+
+	return null;
+}