diff --git a/CHANGELOG.md b/CHANGELOG.md
index 5be565265..1d82af3a7 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -10,6 +10,7 @@ Format follows [Keep a Changelog](https://keepachangelog.com/en/1.1.0/).
 - **`/gsd-ingest-docs` command** — Scan a repo containing mixed ADRs, PRDs, SPECs, and DOCs and bootstrap or merge the full `.planning/` setup from them in a single pass. Parallel classification (`gsd-doc-classifier`), synthesis with precedence rules and cycle detection (`gsd-doc-synthesizer`), three-bucket conflicts report (`INGEST-CONFLICTS.md`: auto-resolved, competing-variants, unresolved-blockers), and hard-block on LOCKED-vs-LOCKED ADR contradictions in both new and merge modes. Supports directory-convention discovery and `--manifest <file>` YAML override with per-doc precedence. v1 caps at 50 docs per invocation; `--resolve interactive` is reserved. Extracts shared conflict-detection contract into `references/doc-conflict-engine.md` which `/gsd-import` now also consumes (#2387)
 
 ### Fixed
+- **SDK `checkAgentsInstalled` is now runtime-aware** — `sdk/src/query/init.ts::checkAgentsInstalled` only knew where Claude Code put agents (`~/.claude/agents`). Users running GSD on Codex, OpenCode, Gemini, Kilo, Copilot, Antigravity, Cursor, Windsurf, Augment, Trae, Qwen, CodeBuddy, or Cline got `agents_installed: false` even with a complete install, which hard-blocked any workflow that gates subagent spawning on that flag. `sdk/src/query/helpers.ts` now resolves the right directory via three-tier detection (`GSD_RUNTIME` env → `config.runtime` → `claude` fallback) and mirrors `bin/install.js::getGlobalDir()` for all 14 runtimes. `GSD_AGENTS_DIR` still short-circuits the chain. `init-runner.ts` stays Claude-only by design (#2402)
 - **`init` query agents-installed check looks at the correct directory** — `checkAgentsInstalled` in `sdk/src/query/init.ts` defaulted to `~/.claude/get-shit-done/agents/`, but the installer writes GSD agents to `~/.claude/agents/`. Every init query therefore reported `agents_installed: false` on clean installs, which made workflows refuse to spawn `gsd-executor` and other parallel subagents. The default now matches `sdk/src/init-runner.ts` and the installer (#2400)
 - **Installer now installs `@gsd-build/sdk` automatically** so `gsd-sdk` lands on PATH. Resolves `command not found: gsd-sdk` errors that affected every `/gsd-*` command after a fresh install or `/gsd-update` to 1.36+. Adds `--no-sdk` to opt out and `--sdk` to force reinstall. Implements the `--sdk` flag that was previously documented in README but never wired up (#2385)
 
diff --git a/sdk/src/query/helpers.test.ts b/sdk/src/query/helpers.test.ts
index 320971dc1..8d8a86952 100644
--- a/sdk/src/query/helpers.test.ts
+++ b/sdk/src/query/helpers.test.ts
@@ -18,7 +18,13 @@ import {
   planningPaths,
   normalizeMd,
   resolvePathUnderProject,
+  resolveAgentsDir,
+  getRuntimeConfigDir,
+  detectRuntime,
+  SUPPORTED_RUNTIMES,
+  type Runtime,
 } from './helpers.js';
+import { homedir } from 'node:os';
 
 // ─── escapeRegex ────────────────────────────────────────────────────────────
 
@@ -252,3 +258,156 @@ describe('resolvePathUnderProject', () => {
     await expect(resolvePathUnderProject(tmpDir, '../../etc/passwd')).rejects.toThrow(GSDError);
   });
 });
+
+// ─── Runtime-aware agents dir resolution (#2402) ───────────────────────────
+
+const RUNTIME_ENV_VARS = [
+  'GSD_AGENTS_DIR', 'GSD_RUNTIME', 'CLAUDE_CONFIG_DIR', 'OPENCODE_CONFIG_DIR',
+  'OPENCODE_CONFIG', 'KILO_CONFIG_DIR', 'KILO_CONFIG', 'XDG_CONFIG_HOME',
+  'GEMINI_CONFIG_DIR', 'CODEX_HOME', 'COPILOT_CONFIG_DIR', 'ANTIGRAVITY_CONFIG_DIR',
+  'CURSOR_CONFIG_DIR', 'WINDSURF_CONFIG_DIR', 'AUGMENT_CONFIG_DIR', 'TRAE_CONFIG_DIR',
+  'QWEN_CONFIG_DIR', 'CODEBUDDY_CONFIG_DIR', 'CLINE_CONFIG_DIR',
+] as const;
+
+describe('getRuntimeConfigDir', () => {
+  const saved: Record<string, string | undefined> = {};
+  beforeEach(() => {
+    for (const k of RUNTIME_ENV_VARS) { saved[k] = process.env[k]; delete process.env[k]; }
+  });
+  afterEach(() => {
+    for (const k of RUNTIME_ENV_VARS) {
+      if (saved[k] === undefined) delete process.env[k];
+      else process.env[k] = saved[k];
+    }
+  });
+
+  const defaults: Record<Runtime, string> = {
+    claude: join(homedir(), '.claude'),
+    opencode: join(homedir(), '.config', 'opencode'),
+    kilo: join(homedir(), '.config', 'kilo'),
+    gemini: join(homedir(), '.gemini'),
+    codex: join(homedir(), '.codex'),
+    copilot: join(homedir(), '.copilot'),
+    antigravity: join(homedir(), '.gemini', 'antigravity'),
+    cursor: join(homedir(), '.cursor'),
+    windsurf: join(homedir(), '.codeium', 'windsurf'),
+    augment: join(homedir(), '.augment'),
+    trae: join(homedir(), '.trae'),
+    qwen: join(homedir(), '.qwen'),
+    codebuddy: join(homedir(), '.codebuddy'),
+    cline: join(homedir(), '.cline'),
+  };
+
+  for (const runtime of SUPPORTED_RUNTIMES) {
+    it(`resolves default path for ${runtime}`, () => {
+      expect(getRuntimeConfigDir(runtime)).toBe(defaults[runtime]);
+    });
+  }
+
+  const envOverrides: Array<[Runtime, string, string]> = [
+    ['claude', 'CLAUDE_CONFIG_DIR', '/x/claude'],
+    ['gemini', 'GEMINI_CONFIG_DIR', '/x/gemini'],
+    ['codex', 'CODEX_HOME', '/x/codex'],
+    ['copilot', 'COPILOT_CONFIG_DIR', '/x/copilot'],
+    ['antigravity', 'ANTIGRAVITY_CONFIG_DIR', '/x/antigravity'],
+    ['cursor', 'CURSOR_CONFIG_DIR', '/x/cursor'],
+    ['windsurf', 'WINDSURF_CONFIG_DIR', '/x/windsurf'],
+    ['augment', 'AUGMENT_CONFIG_DIR', '/x/augment'],
+    ['trae', 'TRAE_CONFIG_DIR', '/x/trae'],
+    ['qwen', 'QWEN_CONFIG_DIR', '/x/qwen'],
+    ['codebuddy', 'CODEBUDDY_CONFIG_DIR', '/x/codebuddy'],
+    ['cline', 'CLINE_CONFIG_DIR', '/x/cline'],
+    ['opencode', 'OPENCODE_CONFIG_DIR', '/x/opencode'],
+    ['kilo', 'KILO_CONFIG_DIR', '/x/kilo'],
+  ];
+  for (const [runtime, envVar, value] of envOverrides) {
+    it(`${runtime} honors ${envVar}`, () => {
+      process.env[envVar] = value;
+      expect(getRuntimeConfigDir(runtime)).toBe(value);
+    });
+  }
+
+  it('opencode uses XDG_CONFIG_HOME when direct vars unset', () => {
+    process.env.XDG_CONFIG_HOME = '/xdg';
+    expect(getRuntimeConfigDir('opencode')).toBe(join('/xdg', 'opencode'));
+  });
+
+  it('opencode OPENCODE_CONFIG uses dirname', () => {
+    process.env.OPENCODE_CONFIG = '/cfg/opencode.json';
+    expect(getRuntimeConfigDir('opencode')).toBe('/cfg');
+  });
+
+  it('kilo uses XDG_CONFIG_HOME when direct vars unset', () => {
+    process.env.XDG_CONFIG_HOME = '/xdg';
+    expect(getRuntimeConfigDir('kilo')).toBe(join('/xdg', 'kilo'));
+  });
+});
+
+describe('detectRuntime', () => {
+  const saved: Record<string, string | undefined> = {};
+  beforeEach(() => {
+    for (const k of RUNTIME_ENV_VARS) { saved[k] = process.env[k]; delete process.env[k]; }
+  });
+  afterEach(() => {
+    for (const k of RUNTIME_ENV_VARS) {
+      if (saved[k] === undefined) delete process.env[k];
+      else process.env[k] = saved[k];
+    }
+  });
+
+  it('defaults to claude with no signals', () => {
+    expect(detectRuntime()).toBe('claude');
+  });
+
+  it('uses GSD_RUNTIME when set to a known runtime', () => {
+    process.env.GSD_RUNTIME = 'codex';
+    expect(detectRuntime()).toBe('codex');
+  });
+
+  it('falls back to config.runtime when GSD_RUNTIME unset', () => {
+    expect(detectRuntime({ runtime: 'gemini' })).toBe('gemini');
+  });
+
+  it('GSD_RUNTIME wins over config.runtime', () => {
+    process.env.GSD_RUNTIME = 'codex';
+    expect(detectRuntime({ runtime: 'gemini' })).toBe('codex');
+  });
+
+  it('unknown GSD_RUNTIME falls through to config then claude', () => {
+    process.env.GSD_RUNTIME = 'bogus';
+    expect(detectRuntime({ runtime: 'gemini' })).toBe('gemini');
+    expect(detectRuntime()).toBe('claude');
+  });
+
+  it('unknown config.runtime falls through to claude', () => {
+    expect(detectRuntime({ runtime: 'bogus' })).toBe('claude');
+  });
+});
+
+describe('resolveAgentsDir (runtime-aware)', () => {
+  const saved: Record<string, string | undefined> = {};
+  beforeEach(() => {
+    for (const k of RUNTIME_ENV_VARS) { saved[k] = process.env[k]; delete process.env[k]; }
+  });
+  afterEach(() => {
+    for (const k of RUNTIME_ENV_VARS) {
+      if (saved[k] === undefined) delete process.env[k];
+      else process.env[k] = saved[k];
+    }
+  });
+
+  it('defaults to Claude agents dir with no args', () => {
+    expect(resolveAgentsDir()).toBe(join(homedir(), '.claude', 'agents'));
+  });
+
+  it('GSD_AGENTS_DIR short-circuits regardless of runtime', () => {
+    process.env.GSD_AGENTS_DIR = '/explicit/agents';
+    expect(resolveAgentsDir('codex')).toBe('/explicit/agents');
+    expect(resolveAgentsDir('claude')).toBe('/explicit/agents');
+  });
+
+  it('appends /agents to the per-runtime config dir', () => {
+    process.env.CODEX_HOME = '/codex';
+    expect(resolveAgentsDir('codex')).toBe(join('/codex', 'agents'));
+  });
+});
diff --git a/sdk/src/query/helpers.ts b/sdk/src/query/helpers.ts
index 6ff012175..2246a3116 100644
--- a/sdk/src/query/helpers.ts
+++ b/sdk/src/query/helpers.ts
@@ -17,27 +17,106 @@
  * ```
  */
 
-import { join, relative, resolve, isAbsolute, normalize } from 'node:path';
+import { join, dirname, relative, resolve, isAbsolute, normalize } from 'node:path';
 import { realpath } from 'node:fs/promises';
 import { homedir } from 'node:os';
 import { GSDError, ErrorClassification } from '../errors.js';
 
-// ─── resolveAgentsDir ──────────────────────────────────────────────────────
+// ─── Runtime-aware agents directory resolution ─────────────────────────────
 
 /**
- * Resolve the Claude Code agents directory using the same precedence as the
- * installer (`bin/install.js` getGlobalDir for Claude):
- *   1. GSD_AGENTS_DIR   — explicit SDK override
- *   2. CLAUDE_CONFIG_DIR/agents — matches installer's --config-dir / env
- *   3. ~/.claude/agents — default
- *
- * Must mirror `bin/install.js:389-396` for Claude. Used by both
- * `query/init.ts:checkAgentsInstalled` and `init-runner.ts`.
+ * Supported GSD runtimes. Kept in sync with `bin/install.js:getGlobalDir()`.
  */
-export function resolveAgentsDir(): string {
+export const SUPPORTED_RUNTIMES = [
+  'claude', 'opencode', 'kilo', 'gemini', 'codex', 'copilot', 'antigravity',
+  'cursor', 'windsurf', 'augment', 'trae', 'qwen', 'codebuddy', 'cline',
+] as const;
+
+export type Runtime = (typeof SUPPORTED_RUNTIMES)[number];
+
+function expandTilde(p: string): string {
+  return p.startsWith('~/') || p === '~' ? join(homedir(), p.slice(1)) : p;
+}
+
+/**
+ * Resolve the per-runtime config directory, mirroring
+ * `bin/install.js:getGlobalDir()`. Agents live at `<configDir>/agents`.
+ */
+export function getRuntimeConfigDir(runtime: Runtime): string {
+  switch (runtime) {
+    case 'claude':
+      return process.env.CLAUDE_CONFIG_DIR
+        ? expandTilde(process.env.CLAUDE_CONFIG_DIR)
+        : join(homedir(), '.claude');
+    case 'opencode':
+      if (process.env.OPENCODE_CONFIG_DIR) return expandTilde(process.env.OPENCODE_CONFIG_DIR);
+      if (process.env.OPENCODE_CONFIG) return dirname(expandTilde(process.env.OPENCODE_CONFIG));
+      if (process.env.XDG_CONFIG_HOME) return join(expandTilde(process.env.XDG_CONFIG_HOME), 'opencode');
+      return join(homedir(), '.config', 'opencode');
+    case 'kilo':
+      if (process.env.KILO_CONFIG_DIR) return expandTilde(process.env.KILO_CONFIG_DIR);
+      if (process.env.KILO_CONFIG) return dirname(expandTilde(process.env.KILO_CONFIG));
+      if (process.env.XDG_CONFIG_HOME) return join(expandTilde(process.env.XDG_CONFIG_HOME), 'kilo');
+      return join(homedir(), '.config', 'kilo');
+    case 'gemini':
+      return process.env.GEMINI_CONFIG_DIR ? expandTilde(process.env.GEMINI_CONFIG_DIR) : join(homedir(), '.gemini');
+    case 'codex':
+      return process.env.CODEX_HOME ? expandTilde(process.env.CODEX_HOME) : join(homedir(), '.codex');
+    case 'copilot':
+      return process.env.COPILOT_CONFIG_DIR ? expandTilde(process.env.COPILOT_CONFIG_DIR) : join(homedir(), '.copilot');
+    case 'antigravity':
+      return process.env.ANTIGRAVITY_CONFIG_DIR ? expandTilde(process.env.ANTIGRAVITY_CONFIG_DIR) : join(homedir(), '.gemini', 'antigravity');
+    case 'cursor':
+      return process.env.CURSOR_CONFIG_DIR ? expandTilde(process.env.CURSOR_CONFIG_DIR) : join(homedir(), '.cursor');
+    case 'windsurf':
+      return process.env.WINDSURF_CONFIG_DIR ? expandTilde(process.env.WINDSURF_CONFIG_DIR) : join(homedir(), '.codeium', 'windsurf');
+    case 'augment':
+      return process.env.AUGMENT_CONFIG_DIR ? expandTilde(process.env.AUGMENT_CONFIG_DIR) : join(homedir(), '.augment');
+    case 'trae':
+      return process.env.TRAE_CONFIG_DIR ? expandTilde(process.env.TRAE_CONFIG_DIR) : join(homedir(), '.trae');
+    case 'qwen':
+      return process.env.QWEN_CONFIG_DIR ? expandTilde(process.env.QWEN_CONFIG_DIR) : join(homedir(), '.qwen');
+    case 'codebuddy':
+      return process.env.CODEBUDDY_CONFIG_DIR ? expandTilde(process.env.CODEBUDDY_CONFIG_DIR) : join(homedir(), '.codebuddy');
+    case 'cline':
+      return process.env.CLINE_CONFIG_DIR ? expandTilde(process.env.CLINE_CONFIG_DIR) : join(homedir(), '.cline');
+  }
+}
+
+/**
+ * Detect the invoking runtime using issue #2402 precedence:
+ *   1. `GSD_RUNTIME` env var
+ *   2. `config.runtime` field (from `.planning/config.json` when loaded)
+ *   3. Fallback to `'claude'`
+ *
+ * Unknown values fall through to the next tier rather than throwing, so
+ * stale env values don't hard-block workflows.
+ */
+export function detectRuntime(config?: { runtime?: unknown }): Runtime {
+  const envValue = process.env.GSD_RUNTIME;
+  if (envValue && (SUPPORTED_RUNTIMES as readonly string[]).includes(envValue)) {
+    return envValue as Runtime;
+  }
+  const configValue = config?.runtime;
+  if (typeof configValue === 'string' && (SUPPORTED_RUNTIMES as readonly string[]).includes(configValue)) {
+    return configValue as Runtime;
+  }
+  return 'claude';
+}
+
+/**
+ * Resolve the GSD agents directory for a given runtime.
+ *
+ * Precedence:
+ *   1. `GSD_AGENTS_DIR` — explicit SDK override (wins over runtime selection)
+ *   2. `<getRuntimeConfigDir(runtime)>/agents` — installer-parity default
+ *
+ * Defaults to Claude when no runtime is passed, matching prior behavior
+ * (see `init-runner.ts`, which is Claude-only by design).
+ */
+export function resolveAgentsDir(runtime: Runtime = 'claude'): string {
   if (process.env.GSD_AGENTS_DIR) return process.env.GSD_AGENTS_DIR;
-  if (process.env.CLAUDE_CONFIG_DIR) return join(process.env.CLAUDE_CONFIG_DIR, 'agents');
-  return join(homedir(), '.claude', 'agents');
+  return join(getRuntimeConfigDir(runtime), 'agents');
 }
 
 // ─── Types ──────────────────────────────────────────────────────────────────
diff --git a/sdk/src/query/init-complex.ts b/sdk/src/query/init-complex.ts
index 3438e98cf..a15112ad7 100644
--- a/sdk/src/query/init-complex.ts
+++ b/sdk/src/query/init-complex.ts
@@ -162,7 +162,7 @@ export const initNewProject: QueryHandler = async (_args, projectDir) => {
     project_path: '.planning/PROJECT.md',
   };
 
-  return { data: withProjectRoot(projectDir, result) };
+  return { data: withProjectRoot(projectDir, result, config as Record<string, unknown>) };
 };
 
 // ─── initProgress ─────────────────────────────────────────────────────────
@@ -309,7 +309,7 @@ export const initProgress: QueryHandler = async (_args, projectDir) => {
     config_path: toPosixPath(relative(projectDir, paths.config)),
   };
 
-  return { data: withProjectRoot(projectDir, result) };
+  return { data: withProjectRoot(projectDir, result, config as Record<string, unknown>) };
 };
 
 // ─── initManager ─────────────────────────────────────────────────────────
@@ -574,5 +574,5 @@ export const initManager: QueryHandler = async (_args, projectDir) => {
     manager_flags: managerFlags,
   };
 
-  return { data: withProjectRoot(projectDir, result) };
+  return { data: withProjectRoot(projectDir, result, config as Record<string, unknown>) };
 };
diff --git a/sdk/src/query/init.test.ts b/sdk/src/query/init.test.ts
index 427c34b85..06d6610c8 100644
--- a/sdk/src/query/init.test.ts
+++ b/sdk/src/query/init.test.ts
@@ -181,6 +181,109 @@ describe('withProjectRoot', () => {
     }
   });
 
+  // #2402 — runtime-aware resolution: GSD_RUNTIME selects which runtime's
+  // config-dir env chain to consult, so non-Claude installs stop
+  // false-negating.
+  it('GSD_RUNTIME=codex resolves agents under CODEX_HOME/agents', async () => {
+    const { MODEL_PROFILES } = await import('./config-query.js');
+    const codexHome = join(tmpDir, 'codex-home');
+    const agentsDir = join(codexHome, 'agents');
+    await mkdir(agentsDir, { recursive: true });
+    for (const name of Object.keys(MODEL_PROFILES)) {
+      await writeFile(join(agentsDir, `${name}.md`), '# stub');
+    }
+    const prevAgents = process.env.GSD_AGENTS_DIR;
+    const prevRuntime = process.env.GSD_RUNTIME;
+    const prevCodex = process.env.CODEX_HOME;
+    delete process.env.GSD_AGENTS_DIR;
+    process.env.GSD_RUNTIME = 'codex';
+    process.env.CODEX_HOME = codexHome;
+    try {
+      const enriched = withProjectRoot(tmpDir, {}) as Record<string, unknown>;
+      expect(enriched.agents_installed).toBe(true);
+      expect(enriched.missing_agents).toEqual([]);
+    } finally {
+      if (prevAgents === undefined) delete process.env.GSD_AGENTS_DIR;
+      else process.env.GSD_AGENTS_DIR = prevAgents;
+      if (prevRuntime === undefined) delete process.env.GSD_RUNTIME;
+      else process.env.GSD_RUNTIME = prevRuntime;
+      if (prevCodex === undefined) delete process.env.CODEX_HOME;
+      else process.env.CODEX_HOME = prevCodex;
+    }
+  });
+
+  it('config.runtime drives detection when GSD_RUNTIME is unset', async () => {
+    const { MODEL_PROFILES } = await import('./config-query.js');
+    const geminiHome = join(tmpDir, 'gemini-home');
+    const agentsDir = join(geminiHome, 'agents');
+    await mkdir(agentsDir, { recursive: true });
+    for (const name of Object.keys(MODEL_PROFILES)) {
+      await writeFile(join(agentsDir, `${name}.md`), '# stub');
+    }
+    const prevAgents = process.env.GSD_AGENTS_DIR;
+    const prevRuntime = process.env.GSD_RUNTIME;
+    const prevGemini = process.env.GEMINI_CONFIG_DIR;
+    delete process.env.GSD_AGENTS_DIR;
+    delete process.env.GSD_RUNTIME;
+    process.env.GEMINI_CONFIG_DIR = geminiHome;
+    try {
+      const enriched = withProjectRoot(tmpDir, {}, { runtime: 'gemini' }) as Record<string, unknown>;
+      expect(enriched.agents_installed).toBe(true);
+    } finally {
+      if (prevAgents === undefined) delete process.env.GSD_AGENTS_DIR;
+      else process.env.GSD_AGENTS_DIR = prevAgents;
+      if (prevRuntime === undefined) delete process.env.GSD_RUNTIME;
+      else process.env.GSD_RUNTIME = prevRuntime;
+      if (prevGemini === undefined) delete process.env.GEMINI_CONFIG_DIR;
+      else process.env.GEMINI_CONFIG_DIR = prevGemini;
+    }
+  });
+
+  it('GSD_RUNTIME wins over config.runtime', async () => {
+    const { MODEL_PROFILES } = await import('./config-query.js');
+    const codexHome = join(tmpDir, 'codex-win');
+    const agentsDir = join(codexHome, 'agents');
+    await mkdir(agentsDir, { recursive: true });
+    for (const name of Object.keys(MODEL_PROFILES)) {
+      await writeFile(join(agentsDir, `${name}.md`), '# stub');
+    }
+    const prevAgents = process.env.GSD_AGENTS_DIR;
+    const prevRuntime = process.env.GSD_RUNTIME;
+    const prevCodex = process.env.CODEX_HOME;
+    delete process.env.GSD_AGENTS_DIR;
+    process.env.GSD_RUNTIME = 'codex';
+    process.env.CODEX_HOME = codexHome;
+    try {
+      // config says gemini, env says codex — codex should win and find agents.
+      const enriched = withProjectRoot(tmpDir, {}, { runtime: 'gemini' }) as Record<string, unknown>;
+      expect(enriched.agents_installed).toBe(true);
+    } finally {
+      if (prevAgents === undefined) delete process.env.GSD_AGENTS_DIR;
+      else process.env.GSD_AGENTS_DIR = prevAgents;
+      if (prevRuntime === undefined) delete process.env.GSD_RUNTIME;
+      else process.env.GSD_RUNTIME = prevRuntime;
+      if (prevCodex === undefined) delete process.env.CODEX_HOME;
+      else process.env.CODEX_HOME = prevCodex;
+    }
+  });
+
+  it('unknown GSD_RUNTIME falls through to config/Claude default', () => {
+    const prevAgents = process.env.GSD_AGENTS_DIR;
+    const prevRuntime = process.env.GSD_RUNTIME;
+    delete process.env.GSD_AGENTS_DIR;
+    process.env.GSD_RUNTIME = 'not-a-runtime';
+    try {
+      // Should not throw; falls back to Claude — missing_agents on a blank tmpDir.
+      const enriched = withProjectRoot(tmpDir, {}) as Record<string, unknown>;
+      expect(typeof enriched.agents_installed).toBe('boolean');
+    } finally {
+      if (prevAgents === undefined) delete process.env.GSD_AGENTS_DIR;
+      else process.env.GSD_AGENTS_DIR = prevAgents;
+      if (prevRuntime === undefined) delete process.env.GSD_RUNTIME;
+      else process.env.GSD_RUNTIME = prevRuntime;
+    }
+  });
+
   it('GSD_AGENTS_DIR takes precedence over CLAUDE_CONFIG_DIR', async () => {
     const { MODEL_PROFILES } = await import('./config-query.js');
     const winningDir = join(tmpDir, 'winning-agents');
diff --git a/sdk/src/query/init.ts b/sdk/src/query/init.ts
index 4a39ab783..ae829297b 100644
--- a/sdk/src/query/init.ts
+++ b/sdk/src/query/init.ts
@@ -27,7 +27,7 @@ import { loadConfig } from '../config.js';
 import { resolveModel, MODEL_PROFILES } from './config-query.js';
 import { findPhase } from './phase.js';
 import { roadmapGetPhase, getMilestoneInfo } from './roadmap.js';
-import { planningPaths, normalizePhaseName, toPosixPath, resolveAgentsDir } from './helpers.js';
+import { planningPaths, normalizePhaseName, toPosixPath, resolveAgentsDir, detectRuntime } from './helpers.js';
 import type { QueryHandler } from './utils.js';
 
 // ─── Internal helpers ──────────────────────────────────────────────────────
@@ -79,10 +79,16 @@ function getLatestCompletedMilestone(projectDir: string): { version: string; nam
 
 /**
  * Check which GSD agents are installed on disk.
+ *
+ * Runtime-aware per issue #2402: detects the invoking runtime
+ * (`GSD_RUNTIME` → `config.runtime` → 'claude') and probes that runtime's
+ * canonical `agents/` directory. `GSD_AGENTS_DIR` still short-circuits.
+ *
  * Port of checkAgentsInstalled from core.cjs lines 1274-1306.
  */
-function checkAgentsInstalled(): { agents_installed: boolean; missing_agents: string[] } {
-  const agentsDir = resolveAgentsDir();
+function checkAgentsInstalled(config?: { runtime?: unknown }): { agents_installed: boolean; missing_agents: string[] } {
+  const runtime = detectRuntime(config);
+  const agentsDir = resolveAgentsDir(runtime);
   const expectedAgents = Object.keys(MODEL_PROFILES);
 
   if (!existsSync(agentsDir)) {
@@ -171,7 +177,7 @@ export function withProjectRoot(
 ): Record<string, unknown> {
   result.project_root = projectDir;
 
-  const agentStatus = checkAgentsInstalled();
+  const agentStatus = checkAgentsInstalled(config);
   result.agents_installed = agentStatus.agents_installed;
   result.missing_agents = agentStatus.missing_agents;