diff --git a/CHANGELOG.md b/CHANGELOG.md
index 8d8ab6f79..042d33f39 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -19,6 +19,8 @@ and adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0.html).
 
 - GitHub Copilot is now a supported agent: `codegraph install` can configure Copilot Chat in VS Code (`copilot-vscode`), the GitHub Copilot CLI (`copilot-cli`), and the Copilot plugin in JetBrains IDEs (`copilot-jetbrains`). Installed Copilot surfaces are auto-detected like every other agent, existing MCP server entries in their config files are preserved, and `codegraph uninstall` reverses the setup cleanly. Restart VS Code or your JetBrains IDE after installing so Copilot picks up the server.
 
+- Codex CLI can now be set up per project instead of only user-wide: `codegraph install --location=local` writes `./.codex/config.toml` and the CodeGraph block in your project's `AGENTS.md`, so CodeGraph is wired into that repo only rather than every Codex session on the machine. `codegraph uninstall --location=local` reverses it, and the global install is untouched either way. Codex only applies a project's config once you've marked the project trusted, so the installer says so after a local install. (#1531)
+
 ### Fixes
 
 - C, C++, Objective-C and Rust unions are now indexed as first-class `union` nodes. A `union` declaration previously produced no symbol at all, so it never appeared in search or `codegraph_explore`, and anything attached to it disappeared with it — in Rust, every `impl SomeTrait for MyUnion` lost its edge, the methods from that impl were left pointing at a type the graph did not contain, and asking which types implement a trait quietly skipped the union ones. A union-shaped dispatch table in C now resolves its function pointers like a struct-shaped one. A `typedef union { … } Name;` in C keeps the typedef's name and is no longer mistaken for a plain type alias. Thanks @ctype-lab. Re-index after upgrading to pick up unions in existing projects. (#1515)
diff --git a/__tests__/installer-targets.test.ts b/__tests__/installer-targets.test.ts
index 0d185a9d8..4ec3e5903 100644
--- a/__tests__/installer-targets.test.ts
+++ b/__tests__/installer-targets.test.ts
@@ -240,6 +240,42 @@ describe('Installer targets — partial-state idempotency', () => {
     expect(mdEntry?.action).toBe('updated');
   });
 
+  it('codex: local install writes ./.codex/config.toml and the project-root ./AGENTS.md block (#1531)', () => {
+    const codex = getTarget('codex')!;
+    const result = codex.install('local', { autoAllow: false });
+    const paths = result.files.map((f) => f.path.replace(/\\/g, '/'));
+    // macOS realpath shenanigans (/var vs /private/var) — suffix match.
+    expect(paths.some((p) => p.endsWith('/.codex/config.toml'))).toBe(true);
+    // AGENTS.md sits at the project root, NOT under .codex/ — that's the
+    // file Codex reads for repo instructions.
+    expect(paths.some((p) => p.endsWith('/AGENTS.md') && !p.includes('/.codex/'))).toBe(true);
+
+    const toml = fs.readFileSync(path.join(process.cwd(), '.codex', 'config.toml'), 'utf-8');
+    expect(toml).toContain('[mcp_servers.codegraph]');
+    expect(fs.readFileSync(path.join(process.cwd(), 'AGENTS.md'), 'utf-8')).toContain('codegraph explore');
+
+    // The project layer is only applied in a trusted project, so say so
+    // instead of reporting a silent success.
+    expect(result.notes?.join(' ')).toMatch(/trusted/);
+
+    // Global config is untouched by a local install.
+    expect(fs.existsSync(path.join(tmpHome, '.codex', 'config.toml'))).toBe(false);
+  });
+
+  it('codex: local uninstall reverses the local install and leaves the global entry alone (#1531)', () => {
+    const codex = getTarget('codex')!;
+    codex.install('global', { autoAllow: false });
+    codex.install('local', { autoAllow: false });
+    expect(codex.detect('local').alreadyConfigured).toBe(true);
+
+    codex.uninstall('local');
+
+    expect(codex.detect('local').alreadyConfigured).toBe(false);
+    expect(codex.detect('global').alreadyConfigured).toBe(true);
+    expect(fs.readFileSync(path.join(tmpHome, '.codex', 'config.toml'), 'utf-8'))
+      .toContain('[mcp_servers.codegraph]');
+  });
+
   it('opencode: prefers .jsonc when both .json and .jsonc exist', () => {
     const opencode = getTarget('opencode')!;
     const dir = path.join(tmpHome, '.config', 'opencode');
diff --git a/src/installer/index.ts b/src/installer/index.ts
index edeb4ac94..9a99ffe34 100644
--- a/src/installer/index.ts
+++ b/src/installer/index.ts
@@ -137,7 +137,7 @@ export async function runInstallerWithOptions(opts: RunInstallerOptions): Promis
   } else if (useDefaults) {
     location = 'global';
   } else {
-    // If every selected target is global-only (e.g. Codex), skip the
+    // If every selected target is global-only (e.g. the Copilot CLI), skip the
     // prompt and force user-wide — project-local would just produce
     // skip warnings.
     const allGlobalOnly = targets.every((t) => !t.supportsLocation('local'));
@@ -328,8 +328,8 @@ export type UninstallStatus = 'removed' | 'not-configured' | 'unsupported';
  * Per-target outcome of an uninstall sweep. `removed` means we deleted
  * at least one thing; `not-configured` means the agent had no codegraph
  * config at this location (nothing to do); `unsupported` means the
- * agent has no config concept for this location (e.g. Codex is
- * global-only, so a `local` uninstall skips it).
+ * agent has no config concept for this location (e.g. the Copilot CLI
+ * is global-only, so a `local` uninstall skips it).
  */
 export interface UninstallReport {
   id: TargetId;
diff --git a/src/installer/targets/codex.ts b/src/installer/targets/codex.ts
index 0a2b8c9c8..d5e361ce3 100644
--- a/src/installer/targets/codex.ts
+++ b/src/installer/targets/codex.ts
@@ -1,15 +1,29 @@
 /**
  * OpenAI Codex CLI target.
  *
- *   - MCP server entry to `~/.codex/config.toml` as the dotted-key
- *     table `[mcp_servers.codegraph]`. TOML — not JSON — handled by
- *     the narrow serializer in `./toml.ts`.
- *   - Instructions to `~/.codex/AGENTS.md`.
+ *   - MCP server entry to `config.toml` as the dotted-key table
+ *     `[mcp_servers.codegraph]`. TOML — not JSON — handled by the
+ *     narrow serializer in `./toml.ts`.
+ *   - Instructions to `AGENTS.md`.
  *
- * Codex CLI as of 2026-05 has no project-local config concept —
- * everything lives under `~/.codex/`. `supportsLocation('local')`
- * returns false; the orchestrator skips Codex when the user picks
- * the local install location.
+ * Both locations are supported (#1531):
+ *   - global: `~/.codex/config.toml` + `~/.codex/AGENTS.md`
+ *   - local:  `<cwd>/.codex/config.toml` + `<cwd>/AGENTS.md`
+ *
+ * Codex has a first-class project config layer: `.codex/config.toml`
+ * is layer 4 of the loader's stack, above the user config (layer 6),
+ * merged recursively top-over-bottom
+ * (`codex-rs/config/src/loader/README.md` in openai/codex). It landed
+ * in openai/codex#8354 (2025-12-22), so the "Codex has no
+ * project-local config" note this file used to carry was never
+ * accurate. The project layer strips a denylist of settings that
+ * repo contents shouldn't get to choose (base URLs, model providers,
+ * `notify`, profiles, otel — `loader/mod.rs`), and `mcp_servers` is
+ * NOT on it, so a project-scoped `[mcp_servers.codegraph]` is honored.
+ *
+ * Caveat surfaced as an install note: project layers are "loaded but
+ * disabled when untrusted," so a local install only takes effect in a
+ * project the user has marked trusted.
  *
  * No permissions concept.
  */
@@ -38,14 +52,31 @@ import { buildTomlTable, removeTomlTable, upsertTomlTable } from './toml';
 
 const TOML_HEADER = 'mcp_servers.codegraph';
 
-function configDir(): string {
-  return path.join(os.homedir(), '.codex');
+function configDir(loc: Location): string {
+  return loc === 'global'
+    ? path.join(os.homedir(), '.codex')
+    : path.join(process.cwd(), '.codex');
+}
+function tomlConfigPath(loc: Location): string {
+  return path.join(configDir(loc), 'config.toml');
 }
-function tomlConfigPath(): string {
-  return path.join(configDir(), 'config.toml');
+function instructionsPath(loc: Location): string {
+  // Global AGENTS.md lives under ~/.codex/; project-local AGENTS.md
+  // lives at the project root (NOT under .codex/) — that's the file
+  // Codex reads for repo instructions, and it matches the local
+  // layout the opencode and gemini targets already use.
+  return loc === 'global'
+    ? path.join(configDir('global'), 'AGENTS.md')
+    : path.join(process.cwd(), 'AGENTS.md');
 }
-function instructionsPath(): string {
-  return path.join(configDir(), 'AGENTS.md');
+
+/**
+ * Project layers are "loaded but disabled when untrusted" (openai/codex
+ * `loader/mod.rs`), so a local install can be written correctly and
+ * still do nothing. Say so rather than reporting silent success.
+ */
+function trustNote(): string {
+  return `Codex applies ${tomlConfigPath('local')} only in a project marked trusted — otherwise the layer is loaded but disabled. Trust this project in Codex to activate it.`;
 }
 
 class CodexTarget implements AgentTarget {
@@ -53,15 +84,12 @@ class CodexTarget implements AgentTarget {
   readonly displayName = 'Codex CLI';
   readonly docsUrl = 'https://github.com/openai/codex';
 
-  supportsLocation(loc: Location): boolean {
-    return loc === 'global';
+  supportsLocation(_loc: Location): boolean {
+    return true;
   }
 
   detect(loc: Location): DetectionResult {
-    if (loc !== 'global') {
-      return { installed: false, alreadyConfigured: false };
-    }
-    const tomlPath = tomlConfigPath();
+    const tomlPath = tomlConfigPath(loc);
     let alreadyConfigured = false;
     if (fs.existsSync(tomlPath)) {
       try {
@@ -69,34 +97,30 @@ class CodexTarget implements AgentTarget {
         alreadyConfigured = content.includes(`[${TOML_HEADER}]`);
       } catch { /* ignore */ }
     }
-    const installed = fs.existsSync(configDir());
+    // Global: ~/.codex/ existing means Codex has run here. Local: the
+    // project only counts as "Codex-enabled" once it actually has a
+    // .codex/ dir or config file of its own.
+    const installed = fs.existsSync(configDir(loc)) || fs.existsSync(tomlPath);
     return { installed, alreadyConfigured, configPath: tomlPath };
   }
 
   install(loc: Location, _opts: InstallOptions): WriteResult {
-    if (loc !== 'global') {
-      return {
-        files: [],
-        notes: ['Codex CLI has no project-local config — re-run with --location=global to install.'],
-      };
-    }
     const files: WriteResult['files'] = [];
 
-    files.push(writeMcpEntry());
+    files.push(writeMcpEntry(loc));
 
     // AGENTS.md gets the short marker-fenced CodeGraph block (#704):
     // subagents and non-MCP harnesses read AGENTS.md but never the MCP
     // initialize instructions. Upsert self-heals a stale pre-#529 block.
-    files.push(upsertInstructionsEntry(instructionsPath()));
+    files.push(upsertInstructionsEntry(instructionsPath(loc)));
 
-    return { files };
+    return loc === 'local' ? { files, notes: [trustNote()] } : { files };
   }
 
   uninstall(loc: Location): WriteResult {
-    if (loc !== 'global') return { files: [] };
     const files: WriteResult['files'] = [];
 
-    const tomlPath = tomlConfigPath();
+    const tomlPath = tomlConfigPath(loc);
     if (fs.existsSync(tomlPath)) {
       const content = fs.readFileSync(tomlPath, 'utf-8');
       const { content: nextContent, action } = removeTomlTable(content, TOML_HEADER);
@@ -114,22 +138,18 @@ class CodexTarget implements AgentTarget {
       files.push({ path: tomlPath, action: 'not-found' });
     }
 
-    files.push(removeInstructionsEntry());
+    files.push(removeInstructionsEntry(loc));
 
     return { files };
   }
 
   printConfig(loc: Location): string {
-    if (loc !== 'global') {
-      return '# Codex CLI has no project-local config — use --location=global.\n';
-    }
     const block = buildCodegraphBlock();
-    return `# Add to ${tomlConfigPath()}\n\n${block}\n`;
+    return `# Add to ${tomlConfigPath(loc)}\n\n${block}\n`;
   }
 
   describePaths(loc: Location): string[] {
-    if (loc !== 'global') return [];
-    return [tomlConfigPath(), instructionsPath()];
+    return [tomlConfigPath(loc), instructionsPath(loc)];
   }
 }
 
@@ -141,8 +161,8 @@ function buildCodegraphBlock(): string {
   });
 }
 
-function writeMcpEntry(): WriteResult['files'][number] {
-  const file = tomlConfigPath();
+function writeMcpEntry(loc: Location): WriteResult['files'][number] {
+  const file = tomlConfigPath(loc);
   const dir = path.dirname(file);
   if (!fs.existsSync(dir)) fs.mkdirSync(dir, { recursive: true });
 
@@ -162,12 +182,12 @@ function writeMcpEntry(): WriteResult['files'][number] {
 }
 
 /**
- * Strip the marker-delimited CodeGraph block from `~/.codex/AGENTS.md`
- * if a prior install wrote one. Used by both install (self-heal on
- * upgrade) and uninstall — see issue #529.
+ * Strip the marker-delimited CodeGraph block from this location's
+ * AGENTS.md if a prior install wrote one. Used by both install
+ * (self-heal on upgrade) and uninstall — see issue #529.
  */
-function removeInstructionsEntry(): WriteResult['files'][number] {
-  const file = instructionsPath();
+function removeInstructionsEntry(loc: Location): WriteResult['files'][number] {
+  const file = instructionsPath(loc);
   const action = removeMarkedSection(file, CODEGRAPH_SECTION_START, CODEGRAPH_SECTION_END);
   return { path: file, action };
 }
diff --git a/src/installer/targets/types.ts b/src/installer/targets/types.ts
index 022ab28e8..d93680573 100644
--- a/src/installer/targets/types.ts
+++ b/src/installer/targets/types.ts
@@ -87,10 +87,10 @@ export interface AgentTarget {
   /**
    * Whether this target supports the given install location.
    *
-   * Some agents (Codex CLI as of 2026-05) have no project-local
-   * config concept — only a single `~/.codex/` dir. Returning false
-   * for an unsupported (target, location) pair lets the orchestrator
-   * skip cleanly with a clear message.
+   * Some agents (GitHub Copilot CLI, the Copilot JetBrains plugin)
+   * have no project-local config concept — only a single per-user
+   * config dir. Returning false for an unsupported (target, location)
+   * pair lets the orchestrator skip cleanly with a clear message.
    */
   supportsLocation(loc: Location): boolean;
   detect(loc: Location): DetectionResult;