diff --git a/packages/web/server/lib/opencode/env-runtime.js b/packages/web/server/lib/opencode/env-runtime.js
index fabfa0a4..7e4cf9d6 100644
--- a/packages/web/server/lib/opencode/env-runtime.js
+++ b/packages/web/server/lib/opencode/env-runtime.js
@@ -11,6 +11,7 @@ export const createOpenCodeEnvRuntime = (deps) => {
     readSettingsFromDiskMigrated,
   } = deps;
   const runSpawnSync = typeof deps.spawnSync === 'function' ? deps.spawnSync : spawnSync;
+  const resolveHomeDir = typeof deps.homedir === 'function' ? deps.homedir : () => os.homedir();
 
   const parseNullSeparatedEnvSnapshot = (raw) => {
     if (typeof raw !== 'string' || raw.length === 0) {
@@ -301,6 +302,14 @@ export const createOpenCodeEnvRuntime = (deps) => {
     return null;
   };
 
+  const bundledOpenCodeCliFallback = () => {
+    const bundled = resolveBundledOpenCodeCliPath();
+    if (!bundled) return null;
+    clearWslOpencodeResolution();
+    state.resolvedOpencodeBinarySource = 'bundled';
+    return bundled;
+  };
+
   const clearWslOpencodeResolution = () => {
     state.useWslForOpencode = false;
     state.resolvedWslBinary = null;
@@ -326,13 +335,9 @@ export const createOpenCodeEnvRuntime = (deps) => {
       }
     }
 
-    const bundled = resolveBundledOpenCodeCliPath();
-    if (bundled) {
-      clearWslOpencodeResolution();
-      state.resolvedOpencodeBinarySource = 'bundled';
-      return bundled;
-    }
-
+    // The bundled CLI is the LAST resort (see bundledOpenCodeCliFallback at the
+    // exit points below): a user's own OpenCode install — PATH, known install
+    // locations, or shell-resolved — must win over the pinned bundled copy.
     const resolvedFromPath = searchPathFor('opencode');
     if (resolvedFromPath) {
       clearWslOpencodeResolution();
@@ -340,7 +345,7 @@ export const createOpenCodeEnvRuntime = (deps) => {
       return resolvedFromPath;
     }
 
-    const home = os.homedir();
+    const home = resolveHomeDir();
     const unixFallbacks = [
       path.join(home, '.opencode', 'bin', 'opencode'),
       path.join(home, '.bun', 'bin', 'opencode'),
@@ -403,7 +408,7 @@ export const createOpenCodeEnvRuntime = (deps) => {
       // Do not auto-detect OpenCode from WSL. OpenCode sessions are keyed by
       // server-visible directories, and mixing Windows paths with WSL paths
       // creates duplicate/missing project state in the desktop app.
-      return null;
+      return bundledOpenCodeCliFallback();
     }
 
     const shells = [process.env.SHELL, '/bin/zsh', '/bin/bash', '/bin/sh'].filter(Boolean);
@@ -427,7 +432,7 @@ export const createOpenCodeEnvRuntime = (deps) => {
       }
     }
 
-    return null;
+    return bundledOpenCodeCliFallback();
   };
 
   const resolveNodeCliPath = () => {
diff --git a/packages/web/server/lib/opencode/env-runtime.test.js b/packages/web/server/lib/opencode/env-runtime.test.js
index f5c5c7c5..8f61b515 100644
--- a/packages/web/server/lib/opencode/env-runtime.test.js
+++ b/packages/web/server/lib/opencode/env-runtime.test.js
@@ -111,6 +111,7 @@ const createRuntime = (settings, options = {}) => {
     normalizeDirectoryPath: (value) => value,
     readSettingsFromDiskMigrated: async () => settings,
     spawnSync: options.spawnSync,
+    homedir: options.homedir,
   });
 
   return { runtime, state };
@@ -149,7 +150,7 @@ describe('OpenCode env runtime', () => {
     expect(state.resolvedOpencodeBinarySource).toBe('settings');
   });
 
-  it('resolves bundled OpenCode CLI before PATH lookup', () => {
+  it('prefers a user-installed OpenCode from PATH over the bundled CLI', () => {
     const bundledDir = createTempDir('openchamber-bundled-opencode-');
     const bundledBinary = path.join(bundledDir, process.platform === 'win32' ? 'opencode.exe' : 'opencode');
     const pathDir = createTempDir('openchamber-path-opencode-');
@@ -165,8 +166,8 @@ describe('OpenCode env runtime', () => {
     delete process.env.OPENCODE_BINARY;
     const { runtime, state } = createRuntime({});
 
-    expect(runtime.resolveOpencodeCliPath()).toBe(bundledBinary);
-    expect(state.resolvedOpencodeBinarySource).toBe('bundled');
+    expect(runtime.resolveOpencodeCliPath()).toBe(pathBinary);
+    expect(state.resolvedOpencodeBinarySource).toBe('path');
   });
 
   it('keeps explicit OpenCode binary ahead of bundled CLI', () => {
@@ -188,7 +189,7 @@ describe('OpenCode env runtime', () => {
     expect(state.resolvedOpencodeBinarySource).toBe('env');
   });
 
-  it('resolves bundled OpenCode CLI from Electron resourcesPath', () => {
+  it('falls back to the bundled OpenCode CLI from Electron resourcesPath when nothing else is installed', () => {
     const resourcesPath = createTempDir('openchamber-resources-');
     const bundledDir = path.join(resourcesPath, 'opencode-cli');
     const bundledBinary = path.join(bundledDir, process.platform === 'win32' ? 'opencode.exe' : 'opencode');
@@ -204,7 +205,13 @@ describe('OpenCode env runtime', () => {
     process.env.PATH = createTempDir('openchamber-empty-path-');
     delete process.env.OPENCHAMBER_BUNDLED_OPENCODE_CLI_DIR;
     delete process.env.OPENCODE_BINARY;
-    const { runtime, state } = createRuntime({});
+    // The bundled CLI is the LAST resort now — hide the machine's own installs
+    // from the home-directory fallbacks and shell discovery.
+    const emptyHome = createTempDir('openchamber-empty-home-');
+    const { runtime, state } = createRuntime({}, {
+      spawnSync: () => ({ status: 1, stdout: '', stderr: '' }),
+      homedir: () => emptyHome,
+    });
 
     expect(runtime.resolveOpencodeCliPath()).toBe(bundledBinary);
     expect(state.resolvedOpencodeBinarySource).toBe('bundled');