feat: shell integration channel (OSC 9001) for color, git, title

CLAUDE.md

@@ -155,6 +155,31 @@ When any override is set, `LaunchSessionAsync` calls `bridge.ApplyProfileOverrid
 
 **Once stamped, profile overrides are independent.** A session keeps its appearance even if the user later edits or deletes the source profile in Windows Terminal.
 
+## Shell Integration (OSC 9001)
+
+Programs running inside a terminal can push session state up to CSM by emitting a custom OSC sequence — useful for SSH overlays (e.g. `nexus`) where CSM cannot inspect the remote repo locally.
+
+> **Integrator-facing reference:** [`docs/shell-integration.md`](docs/shell-integration.md) (wire format + bash/PowerShell/Python/Node/Rust/Go snippets). The notes below are CSM-internal.
+
+**Wire format:** `ESC ] 9001 ; key=value ; key=value … ST`
+
+ST may be `BEL` (`\x07`) or `ESC \\` — xterm.js accepts both.
+
+**Recognised keys:**
+
+| Key | Effect |
+|---|---|
+| `color` | Override the session accent (`#rrggbb` / `#rgb` / `#rrggbbaa`). Repaints sidebar stripe + active ring. 8-digit values use alpha-last (`#rrggbbaa`); CSM converts to WPF's `#aarrggbb` internally. |
+| `git-branch` | Set `SessionViewModel.GitBranch` directly, bypassing `GitService`. |
+| `git-dirty` | `1`/`true` → dirty-marker shown; `0`/anything else → clean. |
+| `title` | Renames the session (calls `vm.Rename`). |
+
+Unknown keys are ignored. Multiple keys can be sent in a single sequence.
+
+**Pipeline:** `terminal-init.js` registers an OSC handler via `term.parser.registerOscHandler(9001, …)` (requires `allowProposedApi: true`, already set). It posts `{type: "shellIntegration", fields: {…}}` to WPF. `TerminalBridge` parses it and raises `ShellIntegrationReceived`. `MainWindow.LaunchSessionAsync` subscribes and calls `vm.ApplyShellIntegration(fields)` on the dispatcher, then `SaveStateAsync` so changes persist.
+
+The OSC handler returns `true` so xterm consumes the sequence and it doesn't render.
+
 ## Sleep / Wake (Dormant Sessions)
 
 Sessions can be put to sleep instead of closed — the PTY is torn down but the `ShellSession` is kept in `state.json` (`IsDormant = true`) so it can be relaunched from the sidebar later. Useful when you have many long-running projects but only need a few live at once.

README.md

@@ -21,6 +21,7 @@ Built with WPF + [xterm.js](https://xtermjs.org/) + Windows ConPTY for full pseu
 - **Alert detection** — detects when Claude is waiting for input or tool approval; green/orange dot indicators
 - **Git status** — shows branch and dirty state in the sidebar per session
 - **Session rename** — double-click any session name or click ✏ to rename inline
+- **Shell integration** — programs running in a session can push their accent color, git branch / dirty state, and tab title to CSM via OSC 9001 (handy for SSH overlays). See [`docs/shell-integration.md`](docs/shell-integration.md).
 - **Auto-resume** — automatically resumes the last Claude Code session when restoring on startup (`--resume <id>`); toggleable in Settings
 - **SSH remote sessions** — connect to remote hosts using your existing SSH config; sessions persist across restarts
 - **Session history** — clicking a search result from a closed session offers to relaunch it

docs/shell-integration.md

@@ -0,0 +1,161 @@
+# CodeShellManager Shell Integration
+
+Programs running inside a CodeShellManager terminal can push session state up to the host UI by emitting a custom OSC (Operating System Command) escape sequence. This is the recommended way for tools like SSH overlays, REPLs, and TUI apps to keep CSM's accent color, git status, and tab title in sync with whatever the program actually represents — even when CSM cannot inspect that state locally.
+
+## Wire format
+
+```
+ESC ] 9001 ; key=value ; key=value … ST
+```
+
+- `ESC` is `\x1b` (`0o33`, `27`).
+- `9001` is the CSM-namespaced OSC identifier.
+- `ST` ("string terminator") is either `BEL` (`\x07`) or `ESC \` (`\x1b\x5c`). Both are accepted.
+- Keys and values are separated by `=`. Multiple fields are separated by `;`.
+- Whitespace around keys/values is trimmed.
+- Unknown keys are silently ignored — safe to emit forward-compatibly.
+- The whole sequence is consumed by xterm and never rendered.
+
+## Recognised keys
+
+| Key          | Value format            | Effect |
+|--------------|-------------------------|--------|
+| `color`      | `#rgb`, `#rrggbb`, `#rrggbbaa` | Override the session accent. Repaints the sidebar stripe and the active-pane ring immediately. 8-digit values use **alpha-last** (`#rrggbbaa`) — CSM converts them internally to WPF's `#aarrggbb` format. |
+| `git-branch` | string                  | Set the branch label shown in the sidebar. Bypasses CSM's local `git` polling — useful for SSH/remote sessions. |
+| `git-dirty`  | `0`/`1` (or `false`/`true`) | Toggle the dirty marker (`*`) shown next to the branch. |
+| `title`      | string                  | Rename the session (same as double-clicking the sidebar entry). Persisted to `state.json`. |
+
+Multiple keys can be sent in a single sequence; CSM applies them atomically and saves state once.
+
+## Examples
+
+All examples below emit `color=#a6e3a1`, `git-branch=feat/foo`, `git-dirty=1`, `title=my-repo` in a single sequence. Adapt to your needs.
+
+### bash / zsh / sh
+
+```bash
+printf '\e]9001;color=#a6e3a1;git-branch=feat/foo;git-dirty=1;title=my-repo\e\\'
+```
+
+To refresh on every prompt, drop this into your shell init:
+
+```bash
+__csm_update() {
+  local branch dirty
+  branch=$(git symbolic-ref --short HEAD 2>/dev/null) || branch=""
+  [ -n "$(git status --porcelain 2>/dev/null)" ] && dirty=1 || dirty=0
+  printf '\e]9001;git-branch=%s;git-dirty=%s\e\\' "$branch" "$dirty"
+}
+PROMPT_COMMAND='__csm_update'    # bash
+# precmd_functions+=(__csm_update)  # zsh
+```
+
+### PowerShell
+
+```powershell
+$esc = [char]27
+"$esc]9001;color=#a6e3a1;git-branch=feat/foo;git-dirty=1;title=my-repo$esc\" | Write-Host -NoNewline
+```
+
+In a `prompt` function:
+
+```powershell
+function prompt {
+    $esc = [char]27
+    $branch = (git symbolic-ref --short HEAD 2>$null)
+    $dirty  = if ((git status --porcelain 2>$null)) { 1 } else { 0 }
+    Write-Host -NoNewline "$esc]9001;git-branch=$branch;git-dirty=$dirty$esc\"
+    "PS $($executionContext.SessionState.Path.CurrentLocation)> "
+}
+```
+
+### Python
+
+```python
+import sys
+
+def csm_update(**fields):
+    payload = ";".join(f"{k}={v}" for k, v in fields.items())
+    sys.stdout.write(f"\x1b]9001;{payload}\x1b\\")
+    sys.stdout.flush()
+
+csm_update(color="#a6e3a1", **{"git-branch": "feat/foo", "git-dirty": "1"}, title="my-repo")
+```
+
+### Node.js
+
+```js
+function csmUpdate(fields) {
+  const payload = Object.entries(fields).map(([k, v]) => `${k}=${v}`).join(';');
+  process.stdout.write(`\x1b]9001;${payload}\x1b\\`);
+}
+
+csmUpdate({ color: '#a6e3a1', 'git-branch': 'feat/foo', 'git-dirty': '1', title: 'my-repo' });
+```
+
+### Rust
+
+```rust
+fn csm_update(fields: &[(&str, &str)]) {
+    let payload: String = fields.iter()
+        .map(|(k, v)| format!("{k}={v}"))
+        .collect::<Vec<_>>()
+        .join(";");
+    print!("\x1b]9001;{payload}\x1b\\");
+    use std::io::Write;
+    let _ = std::io::stdout().flush();
+}
+
+csm_update(&[
+    ("color", "#a6e3a1"),
+    ("git-branch", "feat/foo"),
+    ("git-dirty", "1"),
+    ("title", "my-repo"),
+]);
+```
+
+### Go
+
+```go
+package main
+
+import (
+    "fmt"
+    "strings"
+)
+
+func csmUpdate(fields map[string]string) {
+    parts := make([]string, 0, len(fields))
+    for k, v := range fields {
+        parts = append(parts, k+"="+v)
+    }
+    fmt.Printf("\x1b]9001;%s\x1b\\", strings.Join(parts, ";"))
+}
+```
+
+## Patterns
+
+**Update on every prompt.** Cheap, predictable, and handles `cd` / branch switches automatically. Use the shell snippets above.
+
+**Update on relevant events only.** If a prompt-hook is too coarse — e.g. inside a long-running TUI like `nexus` — call your update function whenever your internal state changes (new repo selected, dirty state changes, branch checked out, etc.).
+
+**Reset on exit.** If your program owns the session's accent for its lifetime, restore the default before exiting:
+
+```bash
+# Clearing color sends the empty string, which CSM treats as "use the default hash"
+# (only true if you've also chosen to clear ColorOverride; currently CSM keeps the
+# last value. To restore the original hash, leave the color key out entirely.)
+```
+
+In the current build, an emitted `color=` is sticky and persists in `state.json` across restarts. If you want it to revert when your program exits, emit nothing extra — but if a different program later runs in the same session, it will inherit your color until it sets its own.
+
+## Limitations
+
+- The protocol is one-way: CSM does not respond to OSC 9001 sequences with any data.
+- There's no acknowledgement that a sequence was parsed. Validate your output with the inspector if you want to be sure (DevTools is enabled in WebView2; press `F12` inside a terminal pane).
+- Color values must be valid CSS hex (`#rgb` / `#rrggbb` / `#rrggbbaa`). Named colors and `rgb()` syntax are rejected.
+- The terminating byte should be `BEL` or `ESC \`. xterm.js will eventually time out an unterminated OSC, but until then your text appears swallowed.
+
+## Pipeline (for CSM contributors)
+
+`terminal-init.js` registers the OSC handler via `term.parser.registerOscHandler(9001, …)`. The handler parses the payload, posts `{type: "shellIntegration", fields: {…}}` over the WebView2 message channel, and returns `true` so xterm consumes the sequence. `TerminalBridge.OnWebMessageReceived` raises `ShellIntegrationReceived`. `MainWindow.LaunchSessionAsync` subscribes and dispatches to `SessionViewModel.ApplyShellIntegration(fields)`, then triggers `SaveStateAsync`. Color/title changes propagate through `INotifyPropertyChanged` to repaint the sidebar stripe and active ring; git fields update `GitBranch` / `GitIsDirty`.

src/CodeShellManager/Assets/terminal-init.js

@@ -32,6 +32,25 @@
   term.open(document.getElementById('terminal'));
   fitAddon.fit();
 
+  // ── Shell integration: OSC 9001;key=value;key=value;ST ─────────────────────
+  // A program inside the terminal can push session state up to CSM by emitting:
+  //   ESC ] 9001 ; color=#89b4fa ; git-branch=main ; git-dirty=1 ; title=foo  ST
+  // Recognised keys: color, git-branch, git-dirty (0/1), title.
+  // Returning true tells xterm we consumed the sequence so it isn't rendered.
+  term.parser.registerOscHandler(9001, data => {
+    try {
+      const fields = {};
+      for (const part of String(data).split(';')) {
+        const eq = part.indexOf('=');
+        if (eq > 0) fields[part.slice(0, eq).trim()] = part.slice(eq + 1).trim();
+      }
+      window.chrome.webview.postMessage(JSON.stringify({
+        type: 'shellIntegration', fields
+      }));
+    } catch {}
+    return true;
+  });
+
   // ── Input → PTY ────────────────────────────────────────────────────────────
   function sendInput(data) {
     window.chrome.webview.postMessage(JSON.stringify({ type: 'input', data }));

src/CodeShellManager/MainWindow.xaml.cs

@@ -346,6 +346,14 @@ private async Task LaunchSessionAsync(ShellSession session, bool restoring = fal
             bridge.RawOutputReceived += alertDetector.Feed;
         }
 
+        // Shell programs (e.g. nexus over SSH) push session state via OSC 9001;
+        // forward those payloads to the VM, then debounce-save so accent/title persist.
+        bridge.ShellIntegrationReceived += fields =>
+        {
+            Dispatcher.Invoke(() => vm.ApplyShellIntegration(fields));
+            _vm.SaveStateDebounced();
+        };
+
         string assetsDir = Path.Combine(AppContext.BaseDirectory, "Assets");
         bool wantTransparent = session.ProfileBackgroundOpacity is < 1.0;
         string htmlFile = wantTransparent ? "terminal-transparent.html" : "terminal.html";
@@ -768,6 +776,15 @@ static void UpdateGitText(TextBlock tb, SessionViewModel svm)
                     case nameof(SessionViewModel.GitInfoLoaded):
                         UpdateGitText(gitText, vm);
                         break;
+
+                    case nameof(SessionViewModel.AccentColor):
+                        try
+                        {
+                            stripe.Background = new SolidColorBrush(
+                                (Color)ColorConverter.ConvertFromString(vm.AccentColor));
+                        }
+                        catch { }
+                        break;
                 }
             });
         };
@@ -1304,6 +1321,21 @@ or nameof(SessionViewModel.IsWaitingForApproval))
                     }
                 });
             }
+            else if (args.PropertyName == nameof(SessionViewModel.AccentColor))
+            {
+                Dispatcher.Invoke(() =>
+                {
+                    try
+                    {
+                        var c = (Color)ColorConverter.ConvertFromString(vm.AccentColor);
+                        wrapper.BorderBrush = new SolidColorBrush(c);
+                        activeRing.Tag = vm.AccentColor;
+                        // If this session is active, re-apply the ring brush immediately
+                        if (vm.IsActive) activeRing.BorderBrush = new SolidColorBrush(c);
+                    }
+                    catch { }
+                });
+            }
         };
 
         return activeRing;

src/CodeShellManager/Services/StateService.cs

@@ -2,12 +2,13 @@
 using System.IO;
 using System.Text.Json;
 using System.Text.Json.Serialization;
+using System.Threading;
 using System.Threading.Tasks;
 using CodeShellManager.Models;
 
 namespace CodeShellManager.Services;
 
-public class StateService
+public class StateService : IDisposable
 {
     private static string StatePath =>
         Environment.GetEnvironmentVariable("CSM_STATE_PATH")
@@ -21,6 +22,8 @@ public class StateService
         DefaultIgnoreCondition = JsonIgnoreCondition.WhenWritingNull
     };
 
+    private readonly SemaphoreSlim _writeLock = new(1, 1);
+
     /// <summary>Returns the resolved state file path (respects CSM_STATE_PATH env var).</summary>
     public static string GetPath() => StatePath;
 
@@ -41,13 +44,25 @@ public async Task<AppState> LoadAsync()
 
     public async Task SaveAsync(AppState state)
     {
+        bool acquired = false;
         try
         {
+            await _writeLock.WaitAsync();
+            acquired = true;
             var path = StatePath;
             Directory.CreateDirectory(Path.GetDirectoryName(path)!);
             string json = JsonSerializer.Serialize(state, Options);
             await File.WriteAllTextAsync(path, json);
         }
-        catch { /* non-critical */ }
+        catch { /* non-critical: disk full, permissions, or serialization errors */ }
+        finally
+        {
+            if (acquired) _writeLock.Release();
+        }
+    }
+
+    public void Dispose()
+    {
+        _writeLock.Dispose();
     }
 }

src/CodeShellManager/Terminal/TerminalBridge.cs

@@ -30,6 +30,12 @@ public sealed class TerminalBridge : IDisposable
     public event Action<string>? RawOutputReceived;
     public event Action? UserInput;
 
+    /// <summary>
+    /// Fires when the running shell program emits OSC 9001 (CSM shell integration).
+    /// Carries the parsed key=value fields it included (color, git-branch, git-dirty, title, …).
+    /// </summary>
+    public event Action<System.Collections.Generic.IReadOnlyDictionary<string, string>>? ShellIntegrationReceived;
+
     /// <summary>
     /// Fires when the user presses a keyboard accelerator (Ctrl-combo, F-key, etc.)
     /// while the WebView2 has focus. Subscribers set <c>e.Handled = true</c> to prevent
@@ -230,6 +236,21 @@ private void OnWebMessageReceived(object? sender, CoreWebView2WebMessageReceived
                             WpfClipboard.SetText(copy));
                     break;
 
+                case "shellIntegration":
+                    if (root.TryGetProperty("fields", out var fieldsEl)
+                        && fieldsEl.ValueKind == JsonValueKind.Object)
+                    {
+                        var dict = new System.Collections.Generic.Dictionary<string, string>(StringComparer.OrdinalIgnoreCase);
+                        foreach (var prop in fieldsEl.EnumerateObject())
+                        {
+                            if (prop.Value.ValueKind == JsonValueKind.String)
+                                dict[prop.Name] = prop.Value.GetString() ?? "";
+                        }
+                        if (dict.Count > 0)
+                            ShellIntegrationReceived?.Invoke(dict);
+                    }
+                    break;
+
                 case "filesDropped":
                     // JS sends full paths via text/uri-list (file:// URIs from Explorer)
                     if (root.TryGetProperty("paths", out var pathsEl))