🤖 Fix tilde (~/) path expansion in SSH exec

Fix bug where tilde paths like ~/cmux/project didn't work for SSH workspaces.

Problem:
- Bash doesn't expand ~ when it's inside quotes
- `cd "~/path"` fails, but `cd ~/path` works
- Previous code did: `cd ${JSON.stringify(cwd)}` which quoted the path
- Tests used absolute paths (/home/...) so bug was not caught

Solution:
- Expand ~/path to $HOME/path before quoting
- `cd "$HOME/path"` works because $HOME expands inside quotes
- Only affects SSH runtime (local runtime doesn't use exec)

Test coverage:
- Added new test: "handles tilde (~/) paths correctly (SSH only)"
- Uses ~/workspace/... instead of absolute path
- All 14 integration tests now passing

Why tests didn't catch it:
- SSH test fixture used hardcoded absolute path: /home/testuser/workspace
- Real users often use tilde paths in config (~/projects, ~/cmux, etc.)
- New test ensures tilde paths work end-to-end

_Generated with `cmux`_

Author: ammar-agent

src/runtime/SSHRuntime.ts

@@ -62,8 +62,14 @@ export class SSHRuntime implements Runtime {
       envPrefix = `export ${envPairs}; `;
     }
 
+    // Expand ~/path to $HOME/path before quoting (~ doesn't expand in quotes)
+    let cwd = options.cwd;
+    if (cwd.startsWith("~/")) {
+      cwd = "$HOME/" + cwd.slice(2);
+    }
+
     // Build full command with cwd and env
-    const fullCommand = `cd ${JSON.stringify(options.cwd)} && ${envPrefix}${command}`;
+    const fullCommand = `cd ${JSON.stringify(cwd)} && ${envPrefix}${command}`;
 
     // Wrap command in bash to ensure bash execution regardless of user's default shell
     // This prevents issues with fish, zsh, or other non-bash shells

tests/ipcMain/createWorkspace.test.ts

@@ -489,6 +489,54 @@ exit 1
             },
             TEST_TIMEOUT_MS
           );
+
+          test.concurrent(
+            "handles tilde (~/) paths correctly (SSH only)",
+            async () => {
+              const env = await createTestEnvironment();
+              const tempGitRepo = await createTempGitRepo();
+
+              try {
+                const branchName = generateBranchName("tilde-test");
+                const trunkBranch = await detectDefaultTrunkBranch(tempGitRepo);
+
+                // Use ~/workspace/... path instead of absolute path
+                const tildeRuntimeConfig: RuntimeConfig = {
+                  type: "ssh",
+                  host: `testuser@localhost`,
+                  workdir: `~/workspace/${branchName}`,
+                  identityFile: sshConfig!.privateKeyPath,
+                  port: sshConfig!.port,
+                };
+
+                const { result, cleanup } = await createWorkspaceWithCleanup(
+                  env,
+                  tempGitRepo,
+                  branchName,
+                  trunkBranch,
+                  tildeRuntimeConfig
+                );
+
+                expect(result.success).toBe(true);
+                if (!result.success) {
+                  throw new Error(`Failed to create workspace with tilde path: ${result.error}`);
+                }
+
+                // Wait for init to complete
+                await new Promise((resolve) => setTimeout(resolve, getInitWaitTime()));
+
+                // Verify workspace exists
+                expect(result.metadata.id).toBeDefined();
+                expect(result.metadata.namedWorkspacePath).toBeDefined();
+
+                await cleanup();
+              } finally {
+                await cleanupTestEnvironment(env);
+                await cleanupTempGitRepo(tempGitRepo);
+              }
+            },
+            TEST_TIMEOUT_MS
+          );
         }
 
       });