diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index 2ebff406..b88818ea 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -58,7 +58,7 @@ jobs:
           - platform: windows-latest
             kind: rust
             task: test
-            timeout-minutes: 30
+            timeout-minutes: 45
 
     name: ${{ matrix.kind }} / ${{ matrix.task }} / ${{ matrix.platform }}
     runs-on: ${{ matrix.platform }}
diff --git a/src-tauri/src/binary_paths.rs b/src-tauri/src/binary_paths.rs
index a3e9dfc2..4bd7ecf2 100644
--- a/src-tauri/src/binary_paths.rs
+++ b/src-tauri/src/binary_paths.rs
@@ -9,6 +9,27 @@ static BINARY_PATHS_CACHE: OnceLock<HashMap<String, String>> = OnceLock::new();
 pub fn get_extended_path() -> String {
   let current_path = env::var("PATH").unwrap_or_default();
 
+  if cfg!(windows) {
+    // The extra locations and `:` joiner below are Unix-specific (Homebrew,
+    // /usr/bin, etc.) and would clobber the inherited PATH — which includes
+    // System32 and PowerShell's own directory — with a broken value. Just
+    // append the running exe's directory, using the Windows `;` separator.
+    let mut all_paths: Vec<String> = current_path
+      .split(';')
+      .filter(|p| !p.is_empty())
+      .map(String::from)
+      .collect();
+    if let Ok(exe_path) = std::env::current_exe() {
+      if let Some(exe_dir) = exe_path.parent() {
+        let exe_dir_str = exe_dir.to_string_lossy().to_string();
+        if !exe_dir_str.is_empty() && !all_paths.contains(&exe_dir_str) {
+          all_paths.push(exe_dir_str);
+        }
+      }
+    }
+    return all_paths.join(";");
+  }
+
   // Common binary locations to add
   let additional_paths = vec![
     "/opt/homebrew/bin", // macOS ARM Homebrew
@@ -64,8 +85,25 @@ pub fn get_exe_dir() -> Option<String> {
   }
 }
 
-/// Detect binary path using `which` command with extended PATH
+/// Detect binary path using `which` (Unix) or `where` (Windows) with extended PATH
 pub fn detect_binary(name: &str) -> Option<String> {
+  if cfg!(windows) {
+    // `which` isn't available by default on Windows, and `get_extended_path`
+    // joins entries with `:` (a Unix path separator), so neither applies here.
+    // `where` uses the process's own PATH and is present on all supported Windows versions.
+    let output = Command::new("where").arg(name).output().ok()?;
+
+    if output.status.success() {
+      let stdout = String::from_utf8(output.stdout).ok()?;
+      let path = stdout.lines().next().unwrap_or("").trim().to_string();
+      if !path.is_empty() {
+        return Some(path);
+      }
+    }
+
+    return None;
+  }
+
   let extended_path = get_extended_path();
 
   // Try using `which` with extended PATH
diff --git a/src-tauri/src/core/agent_cli.rs b/src-tauri/src/core/agent_cli.rs
index d74299f1..6693dec3 100644
--- a/src-tauri/src/core/agent_cli.rs
+++ b/src-tauri/src/core/agent_cli.rs
@@ -230,7 +230,10 @@ mod tests {
 
     let settings_path = files.settings_path.expect("settings path");
     let settings = fs::read_to_string(&settings_path).expect("read settings");
-    assert!(settings.contains(&files.skill_dir));
+    // skill_dir may contain backslashes (Windows), which JSON escapes as `\\`;
+    // compare against the JSON-encoded form rather than the raw path string.
+    let skill_dir_json = serde_json::to_string(&files.skill_dir).expect("encode skill_dir");
+    assert!(settings.contains(skill_dir_json.trim_matches('"')));
     assert!(settings.contains("/ws"));
     assert!(!settings.contains("sandbox"));
     let value: Value = serde_json::from_str(&settings).expect("parse settings");
@@ -292,7 +295,15 @@ mod tests {
 
   #[test]
   fn cleanup_refuses_paths_outside_temp_prefix() {
-    let result = cleanup_agent_cli_files(&["/etc/passwd".to_string()]);
+    // Must exist on every platform: canonicalize() only rejects paths that don't
+    // resolve; /etc/passwd doesn't exist on Windows, so it would be silently
+    // skipped instead of exercising the temp-prefix check. The running test
+    // binary always exists and is never under the treq-agent temp prefix.
+    let outside_path = std::env::current_exe()
+      .expect("current_exe")
+      .to_string_lossy()
+      .into_owned();
+    let result = cleanup_agent_cli_files(&[outside_path]);
     assert!(result.is_err());
   }
 
@@ -377,6 +388,10 @@ mod tests {
     cleanup_agent_cli_files(&[files.prompt_path, files.skill_dir]).expect("cleanup");
   }
 
+  // Windows' read-only directory attribute doesn't block creating files inside
+  // the directory (unlike Unix's write-permission bit), so this test's simulated
+  // permission denial is a no-op there and the skip path never triggers.
+  #[cfg(not(windows))]
   #[test]
   fn skips_project_skills_when_cwd_is_not_writable() {
     let cwd = tempfile::TempDir::new().expect("cwd");
diff --git a/src-tauri/src/core/checks.rs b/src-tauri/src/core/checks.rs
index 0543408c..ac14672c 100644
--- a/src-tauri/src/core/checks.rs
+++ b/src-tauri/src/core/checks.rs
@@ -88,7 +88,9 @@ fn validate_filename(filename: &str) -> Result<(), String> {
 }
 
 fn validate_working_directory(wd: &str) -> Result<(), String> {
-  if Path::new(wd).is_absolute() {
+  // `Path::is_absolute()` only recognizes drive-rooted paths on Windows (e.g. `C:\foo`),
+  // so a Unix-style `/foo` slips past it there. Reject a leading separator explicitly.
+  if Path::new(wd).is_absolute() || wd.starts_with('/') || wd.starts_with('\\') {
     return Err(format!(
       "working-directory must be a relative path, got: '{}'",
       wd
diff --git a/src-tauri/src/core/mod.rs b/src-tauri/src/core/mod.rs
index eb4710f6..69290bf1 100644
--- a/src-tauri/src/core/mod.rs
+++ b/src-tauri/src/core/mod.rs
@@ -95,7 +95,8 @@ mod tests {
     std::env::set_var("TREQ_APP_DATA_DIR", "/tmp/app-data");
 
     let resolved = resolve_app_db_path("/repo/path");
-    assert_eq!(resolved.to_string_lossy(), "/tmp/app-data/treq.db");
+    let expected = std::path::Path::new("/tmp/app-data").join("treq.db");
+    assert_eq!(resolved, expected);
 
     std::env::remove_var("TREQ_APP_DATA_DIR");
   }
diff --git a/src-tauri/src/core/workspaces.rs b/src-tauri/src/core/workspaces.rs
index eea5941f..28ce6357 100644
--- a/src-tauri/src/core/workspaces.rs
+++ b/src-tauri/src/core/workspaces.rs
@@ -1206,6 +1206,17 @@ mod tests {
       .status()
       .expect("jj init");
     assert!(status.success());
+    // get_default_branch() falls back to git's init.defaultBranch config once no
+    // "main"/"master" branch ref exists yet (true here: no commit has been made,
+    // so the colocated repo has no real git branch ref at all). That config
+    // depends on the runner's git version/settings (observed "master" on the
+    // Windows CI image); pin it to "main" so resolution is deterministic.
+    let status = Command::new("git")
+      .current_dir(temp.path())
+      .args(["config", "init.defaultBranch", "main"])
+      .status()
+      .expect("git config init.defaultBranch");
+    assert!(status.success());
     let repo_path = temp.path().to_str().expect("utf8 path").to_string();
     crate::jj::jj_set_bookmark(&repo_path, "main", "@").expect("set main bookmark");
     repo_path
diff --git a/src-tauri/src/pty.rs b/src-tauri/src/pty.rs
index 77016267..e4acf869 100644
--- a/src-tauri/src/pty.rs
+++ b/src-tauri/src/pty.rs
@@ -78,9 +78,31 @@ pub struct PtySession {
   auto_command: Arc<Mutex<Option<String>>>,
 }
 
+/// Windows shells (PowerShell/cmd) submit a line on carriage return; a bare `\n`
+/// with no preceding `\r` is inserted into PSReadLine's buffer instead of
+/// submitting it, so callers on Windows never see command output. Insert the
+/// missing `\r` before any bare `\n`, leaving existing `\r\n` untouched.
+fn translate_line_endings_for_windows(data: &[u8]) -> Vec<u8> {
+  let mut out = Vec::with_capacity(data.len());
+  let mut prev = 0u8;
+  for &b in data {
+    if b == b'\n' && prev != b'\r' {
+      out.push(b'\r');
+    }
+    out.push(b);
+    prev = b;
+  }
+  out
+}
+
 impl PtySession {
   pub fn write(&mut self, data: &[u8]) -> std::io::Result<()> {
-    self.writer.write_all(data)?;
+    if cfg!(windows) {
+      let translated = translate_line_endings_for_windows(data);
+      self.writer.write_all(&translated)?;
+    } else {
+      self.writer.write_all(data)?;
+    }
     self.writer.flush()
   }
 
@@ -293,11 +315,29 @@ impl PtyManager {
             break;
           }
           Ok(n) => {
-            let data = process_utf8_chunk(&mut pending_bytes, &buffer[..n]);
+            let mut data = process_utf8_chunk(&mut pending_bytes, &buffer[..n]);
             if data.is_empty() {
               continue;
             }
 
+            // Windows console apps running under ConPTY (e.g. PowerShell/PSReadLine
+            // at startup) query the cursor position via a VT100 Device Status Report
+            // and block on the pty until something answers. The app's real terminal
+            // (xterm.js) answers this itself; this raw reader has no such emulator
+            // attached, so answer it here with a fixed position to unblock the child.
+            const CURSOR_POS_QUERY: &str = "\x1b[6n";
+            if cfg!(windows) && data.contains(CURSOR_POS_QUERY) {
+              let mut sessions = reader_sessions.lock().unwrap();
+              if let Some(session) = sessions.get_mut(&reader_session_id) {
+                let _ = session.write(b"\x1b[1;1R");
+              }
+              drop(sessions);
+              data = data.replace(CURSOR_POS_QUERY, "");
+              if data.is_empty() {
+                continue;
+              }
+            }
+
             // Check if filtering is active
             let filter_cmd = {
               let guard = auto_command_reader.lock().unwrap();
@@ -536,7 +576,14 @@ mod tests {
       )
       .unwrap();
 
-    let deadline = Instant::now() + Duration::from_secs(2);
+    // PowerShell's cold-start time on CI Windows runners can exceed 2s on its own,
+    // before it even processes the queued "exit" — give it more headroom there.
+    let timeout = if cfg!(windows) {
+      Duration::from_secs(10)
+    } else {
+      Duration::from_secs(2)
+    };
+    let deadline = Instant::now() + timeout;
     while manager.session_exists("eof") && Instant::now() < deadline {
       thread::sleep(Duration::from_millis(10));
     }
@@ -565,12 +612,22 @@ mod tests {
   fn echo_suppression_releases_output_after_bounded_buffer() {
     let manager = PtyManager::new();
     let (tx, rx) = mpsc::channel();
+    // `yes`/`head` aren't available under PowerShell; emit the same >32KB of
+    // filler in one shot so the filter's MAX_FILTER_BUFFER release path is
+    // exercised the same way on both platforms.
+    let command = if cfg!(windows) {
+      // Many small writes flush through ConPTY more reliably than one very long
+      // line, which can sit behind console line-wrap handling before it's sent.
+      "for($i=0;$i -lt 1000;$i++){Write-Output ('x' * 50)}".to_string()
+    } else {
+      "yes x | head -c 40000".to_string()
+    };
     manager
       .create_session(
         "bounded-filter".into(),
         None,
         shell(),
-        Some("yes x | head -c 40000".into()),
+        Some(command),
         Some("echo-that-will-never-appear-0123456789".into()),
         Box::new(move |chunk| {
           let _ = tx.send(chunk);
@@ -578,7 +635,14 @@ mod tests {
       )
       .unwrap();
 
-    assert!(rx.recv_timeout(Duration::from_secs(2)).is_ok());
+    // Windows CI runs this alongside ~300 other tests contending for CPU/IO, on
+    // top of PowerShell's own slower cold-start; give it much more headroom.
+    let timeout = if cfg!(windows) {
+      Duration::from_secs(30)
+    } else {
+      Duration::from_secs(2)
+    };
+    assert!(rx.recv_timeout(timeout).is_ok());
     manager.close_session("bounded-filter").unwrap();
   }
 }
diff --git a/src-tauri/tests/core_workspaces_sparse_checkout_test.rs b/src-tauri/tests/core_workspaces_sparse_checkout_test.rs
index 709c943d..70c01277 100644
--- a/src-tauri/tests/core_workspaces_sparse_checkout_test.rs
+++ b/src-tauri/tests/core_workspaces_sparse_checkout_test.rs
@@ -352,12 +352,16 @@ fn files_outside_sparse_patterns_are_not_snapshotted() {
   let tree_files = TestRepo::run_jj(ws_str, &["file", "list", "-r", "feat/sparse-snapshot"])
     .expect("Failed to list files at branch");
   assert!(
-    tree_files.lines().any(|l| l.trim() == "src/new.rs"),
+    tree_files
+      .lines()
+      .any(|l| l.trim().replace('\\', "/") == "src/new.rs"),
     "committed tree should contain src/new.rs, got: {}",
     tree_files
   );
   assert!(
-    !tree_files.lines().any(|l| l.trim() == "docs/new.md"),
+    !tree_files
+      .lines()
+      .any(|l| l.trim().replace('\\', "/") == "docs/new.md"),
     "committed tree should not contain docs/new.md, got: {}",
     tree_files
   );
diff --git a/src-tauri/tests/e2e_test_helpers.rs b/src-tauri/tests/e2e_test_helpers.rs
index 6dba8588..b7e348f2 100644
--- a/src-tauri/tests/e2e_test_helpers.rs
+++ b/src-tauri/tests/e2e_test_helpers.rs
@@ -77,6 +77,10 @@ impl TestRepo {
     Self::run_git(&repo_path, &["config", "user.email", "test@example.com"])?;
     Self::run_git(&repo_path, &["config", "user.name", "Test User"])?;
 
+    // Tests assert on exact file bytes; without this, Windows git installs
+    // that default to core.autocrlf=true rewrite LF to CRLF on checkout.
+    Self::run_git(&repo_path, &["config", "core.autocrlf", "false"])?;
+
     let default_branch = random_default_branch_name();
     Self::run_git(&repo_path, &["branch", "-M", &default_branch])
       .map_err(|e| format!("Failed to create default branch: {}", e))?;