diff --git a/.opencode/README.md b/.opencode/README.md
index 6fe4657f53..e8c845fcff 100644
--- a/.opencode/README.md
+++ b/.opencode/README.md
@@ -57,6 +57,19 @@ cd ECC
 opencode
 ```
 
+If you also want to apply the ECC home install
+(`node scripts/install-apply.js --target opencode --profile full`), build the
+plugin first so the compiled payload at `.opencode/dist/` exists:
+
+```bash
+node scripts/build-opencode.js   # or: npm run build:opencode
+node scripts/install-apply.js --target opencode --profile full
+```
+
+Without `.opencode/dist/index.js`, OpenCode will detect the slash commands
+but silently skip plugin hooks and tools. The installer now fails fast with
+a pointer to this command if the build step is missing.
+
 ## Features
 
 ### Agents (12)
diff --git a/scripts/lib/install-targets/opencode-home.js b/scripts/lib/install-targets/opencode-home.js
index c8e629e47b..56880235c5 100644
--- a/scripts/lib/install-targets/opencode-home.js
+++ b/scripts/lib/install-targets/opencode-home.js
@@ -1,4 +1,83 @@
-const { createInstallTargetAdapter } = require('./helpers');
+const fs = require('fs');
+const os = require('os');
+const path = require('path');
+
+const {
+  buildValidationIssue,
+  createInstallTargetAdapter,
+} = require('./helpers');
+
+const COMPILED_PLUGIN_DIST_DIR = path.join('.opencode', 'dist');
+const REQUIRED_COMPILED_ARTEFACTS = Object.freeze([
+  { relativePath: path.join(COMPILED_PLUGIN_DIST_DIR, 'index.js'), expectedType: 'file' },
+  { relativePath: path.join(COMPILED_PLUGIN_DIST_DIR, 'plugins'), expectedType: 'directory' },
+  { relativePath: path.join(COMPILED_PLUGIN_DIST_DIR, 'tools'), expectedType: 'directory' },
+]);
+const BUILD_COMMAND_HINT = 'node scripts/build-opencode.js (or: npm run build:opencode)';
+
+// Errors that mean "this artefact does not exist at the expected path / type".
+// Anything else (EACCES, EIO, ...) is a genuine system fault we surface to the
+// caller rather than masking as a missing artefact.
+const MISSING_ARTEFACT_ERROR_CODES = new Set(['ENOENT', 'ENOTDIR']);
+
+function isExpectedType(absolutePath, expectedType) {
+  let stat;
+  try {
+    stat = fs.statSync(absolutePath);
+  } catch (error) {
+    if (error && MISSING_ARTEFACT_ERROR_CODES.has(error.code)) {
+      return false;
+    }
+    throw error;
+  }
+  return expectedType === 'file' ? stat.isFile() : stat.isDirectory();
+}
+
+function defaultValidateOpencodeHome(input = {}) {
+  if (!input.homeDir && !os.homedir()) {
+    return [
+      buildValidationIssue(
+        'error',
+        'missing-home-dir',
+        'homeDir is required for home install targets'
+      ),
+    ];
+  }
+
+  if (!input.repoRoot) {
+    return [];
+  }
+
+  const missingPaths = REQUIRED_COMPILED_ARTEFACTS
+    .map(artefact => ({
+      relativePath: artefact.relativePath,
+      absolutePath: path.join(input.repoRoot, artefact.relativePath),
+      expectedType: artefact.expectedType,
+    }))
+    .filter(entry => !isExpectedType(entry.absolutePath, entry.expectedType));
+
+  if (missingPaths.length > 0) {
+    const missingList = missingPaths.map(entry => entry.relativePath).join(', ');
+    return [
+      buildValidationIssue(
+        'error',
+        'opencode-plugin-not-built',
+        'OpenCode install requires the compiled plugin payload under '
+          + `${COMPILED_PLUGIN_DIST_DIR}, but the following artefact(s) were `
+          + `missing or had the wrong type: ${missingList}. Run `
+          + `${BUILD_COMMAND_HINT} from the repo root before re-running the `
+          + 'installer.',
+        {
+          missingPaths: missingPaths.map(entry => entry.absolutePath),
+          missingRelativePaths: missingPaths.map(entry => entry.relativePath),
+          expectedTypes: missingPaths.map(entry => entry.expectedType),
+        }
+      ),
+    ];
+  }
+
+  return [];
+}
 
 module.exports = createInstallTargetAdapter({
   id: 'opencode-home',
@@ -7,4 +86,5 @@ module.exports = createInstallTargetAdapter({
   rootSegments: ['.opencode'],
   installStatePathSegments: ['ecc-install-state.json'],
   nativeRootRelativePath: '.opencode',
+  validate: defaultValidateOpencodeHome,
 });
diff --git a/tests/lib/install-targets.test.js b/tests/lib/install-targets.test.js
index d74d95aa28..f59afd8edc 100644
--- a/tests/lib/install-targets.test.js
+++ b/tests/lib/install-targets.test.js
@@ -3,6 +3,8 @@
  */
 
 const assert = require('assert');
+const fs = require('fs');
+const os = require('os');
 const path = require('path');
 
 const {
@@ -966,6 +968,132 @@ function runTests() {
     );
   })) passed++; else failed++;
 
+  if (test('resolves opencode adapter root and install-state path from home dir', () => {
+    const adapter = getInstallTargetAdapter('opencode');
+    const homeDir = '/Users/example';
+    const root = adapter.resolveRoot({ homeDir });
+    const statePath = adapter.getInstallStatePath({ homeDir });
+
+    assert.strictEqual(adapter.id, 'opencode-home');
+    assert.strictEqual(adapter.target, 'opencode');
+    assert.strictEqual(adapter.kind, 'home');
+    assert.strictEqual(root, path.join(homeDir, '.opencode'));
+    assert.strictEqual(statePath, path.join(homeDir, '.opencode', 'ecc-install-state.json'));
+  })) passed++; else failed++;
+
+  if (test('opencode adapter validate reports an error when compiled plugin is missing', () => {
+    const adapter = getInstallTargetAdapter('opencode');
+    const repoRoot = fs.mkdtempSync(path.join(os.tmpdir(), 'install-targets-opencode-missing-'));
+    try {
+      const issues = adapter.validate({ homeDir: '/Users/example', repoRoot });
+      assert.strictEqual(issues.length, 1, 'Should surface exactly one validation issue');
+      assert.strictEqual(issues[0].severity, 'error');
+      assert.strictEqual(issues[0].code, 'opencode-plugin-not-built');
+      assert.ok(
+        issues[0].message.includes('.opencode/dist') || issues[0].message.includes('.opencode\\dist'),
+        'Validation message should reference the .opencode/dist payload location'
+      );
+      assert.ok(
+        issues[0].message.includes('build-opencode.js') || issues[0].message.includes('build:opencode'),
+        'Validation message should hint at the build command'
+      );
+      assert.ok(Array.isArray(issues[0].missingRelativePaths) && issues[0].missingRelativePaths.length >= 1,
+        'Validation issue should expose the list of missing artefacts as metadata');
+    } finally {
+      fs.rmSync(repoRoot, { recursive: true, force: true });
+    }
+  })) passed++; else failed++;
+
+  if (test('opencode adapter validate reports a partial build (entry present, runtime dirs absent)', () => {
+    const adapter = getInstallTargetAdapter('opencode');
+    const repoRoot = fs.mkdtempSync(path.join(os.tmpdir(), 'install-targets-opencode-partial-'));
+    try {
+      const distDir = path.join(repoRoot, '.opencode', 'dist');
+      fs.mkdirSync(distDir, { recursive: true });
+      fs.writeFileSync(path.join(distDir, 'index.js'), '// stub\n');
+      // Intentionally omit dist/plugins and dist/tools.
+
+      const issues = adapter.validate({ homeDir: '/Users/example', repoRoot });
+      assert.strictEqual(issues.length, 1, 'Should surface a single validation issue for partial builds');
+      assert.strictEqual(issues[0].code, 'opencode-plugin-not-built');
+      const missing = issues[0].missingRelativePaths.map(p => p.replace(/\\/g, '/'));
+      assert.ok(missing.includes('.opencode/dist/plugins'), 'Missing list should include dist/plugins');
+      assert.ok(missing.includes('.opencode/dist/tools'), 'Missing list should include dist/tools');
+      assert.ok(!missing.includes('.opencode/dist/index.js'), 'Missing list should not include the present entry');
+    } finally {
+      fs.rmSync(repoRoot, { recursive: true, force: true });
+    }
+  })) passed++; else failed++;
+
+  if (test('opencode adapter validate rejects wrong artefact type (file where directory expected)', () => {
+    const adapter = getInstallTargetAdapter('opencode');
+    const repoRoot = fs.mkdtempSync(path.join(os.tmpdir(), 'install-targets-opencode-wrongtype-'));
+    try {
+      const distDir = path.join(repoRoot, '.opencode', 'dist');
+      fs.mkdirSync(distDir, { recursive: true });
+      fs.writeFileSync(path.join(distDir, 'index.js'), '// stub\n');
+      // Materialize plugins/tools as files instead of directories.
+      fs.writeFileSync(path.join(distDir, 'plugins'), 'not-a-dir');
+      fs.writeFileSync(path.join(distDir, 'tools'), 'not-a-dir');
+
+      const issues = adapter.validate({ homeDir: '/Users/example', repoRoot });
+      assert.strictEqual(issues.length, 1, 'Wrong-type artefacts should still surface a validation issue');
+      assert.strictEqual(issues[0].code, 'opencode-plugin-not-built');
+      const missing = issues[0].missingRelativePaths.map(p => p.replace(/\\/g, '/'));
+      assert.ok(missing.includes('.opencode/dist/plugins'), 'Should flag plugins file as wrong type');
+      assert.ok(missing.includes('.opencode/dist/tools'), 'Should flag tools file as wrong type');
+      assert.ok(!missing.includes('.opencode/dist/index.js'), 'Should not flag index.js when it is correctly a file');
+    } finally {
+      fs.rmSync(repoRoot, { recursive: true, force: true });
+    }
+  })) passed++; else failed++;
+
+  if (test('opencode adapter validate handles ENOTDIR (intermediate path is a file) without throwing', () => {
+    const adapter = getInstallTargetAdapter('opencode');
+    const repoRoot = fs.mkdtempSync(path.join(os.tmpdir(), 'install-targets-opencode-enotdir-'));
+    try {
+      // Create `.opencode/dist` as a regular file. Stat'ing
+      // `.opencode/dist/index.js` then throws ENOTDIR (intermediate component
+      // is a file, not a directory). The validate gate must treat this as a
+      // missing artefact and surface the structured opencode-plugin-not-built
+      // issue, not propagate the raw fs error.
+      const opencodeDir = path.join(repoRoot, '.opencode');
+      fs.mkdirSync(opencodeDir, { recursive: true });
+      fs.writeFileSync(path.join(opencodeDir, 'dist'), 'not-a-dir');
+
+      let issues;
+      assert.doesNotThrow(
+        () => { issues = adapter.validate({ homeDir: '/Users/example', repoRoot }); },
+        'validate should swallow ENOTDIR and surface a structured issue'
+      );
+      assert.strictEqual(issues.length, 1, 'ENOTDIR case should produce exactly one validation issue');
+      assert.strictEqual(issues[0].severity, 'error');
+      assert.strictEqual(issues[0].code, 'opencode-plugin-not-built');
+      const missing = issues[0].missingRelativePaths.map(p => p.replace(/\\/g, '/'));
+      assert.ok(missing.includes('.opencode/dist/index.js'), 'ENOTDIR target should be reported as missing');
+      assert.ok(missing.includes('.opencode/dist/plugins'), 'Sibling artefacts under the bad path should be reported');
+      assert.ok(missing.includes('.opencode/dist/tools'), 'Sibling artefacts under the bad path should be reported');
+    } finally {
+      fs.rmSync(repoRoot, { recursive: true, force: true });
+    }
+  })) passed++; else failed++;
+
+  if (test('opencode adapter validate passes once compiled plugin payload exists', () => {
+    const adapter = getInstallTargetAdapter('opencode');
+    const repoRoot = fs.mkdtempSync(path.join(os.tmpdir(), 'install-targets-opencode-built-'));
+    try {
+      const distDir = path.join(repoRoot, '.opencode', 'dist');
+      fs.mkdirSync(path.join(distDir, 'plugins'), { recursive: true });
+      fs.mkdirSync(path.join(distDir, 'tools'), { recursive: true });
+      fs.writeFileSync(path.join(distDir, 'index.js'), '// stub\n');
+
+      const issues = adapter.validate({ homeDir: '/Users/example', repoRoot });
+      assert.deepStrictEqual(issues, [], 'Should not surface validation issues when plugin is built');
+    } finally {
+      fs.rmSync(repoRoot, { recursive: true, force: true });
+    }
+  })) passed++; else failed++;
+
   console.log(`\nResults: Passed: ${passed}, Failed: ${failed}`);
   process.exit(failed > 0 ? 1 : 0);
 }