Scope git history to current diagram by default

- History panel defaults to "This diagram" / "All" toggle
- "This diagram" filters git log to commits that touched only that
  diagram's JSON file (git log -- diagrams/0001_*.json)
- Automatically switches to "All" when no diagram is open
- Restore flow still works per-commit, per-file

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

backend/app/routers/git_mgr.py

@@ -185,9 +185,13 @@ def git_status():
 
 
 @router.get("/log")
-def git_log():
+def git_log(diagram_id: Optional[int] = None):
     repo_root = _repo_root()
-    r = _run("log", "--pretty=format:%H|%h|%s|%an|%ai", "-30", cwd=repo_root)
+    cmd = ["log", "--pretty=format:%H|%h|%s|%an|%ai", "--follow", "-50"]
+    if diagram_id is not None:
+        # Filter to commits that touched this diagram's file (glob by id prefix)
+        cmd += ["--", f"diagrams/{diagram_id:04d}_*.json"]
+    r = _run(*cmd, cwd=repo_root)
     if r.returncode != 0:
         return []
     entries = []

frontend/css/main.css

@@ -326,6 +326,14 @@ button:active { background: #1a1a3a; }
 .git-hash { font-family: monospace; color: #6688cc; font-size: 11px; }
 .git-msg  { color: #bbc; font-size: 11px; white-space: nowrap; overflow: hidden; text-overflow: ellipsis; }
 .git-date { color: #445; font-size: 10px; text-align: right; }
+.git-scope-btn {
+  font-size: 10px; padding: 2px 8px;
+  background: #111122; border: 1px solid #2a2a44; color: #445566; cursor: pointer;
+}
+.git-scope-btn:first-of-type { border-radius: 3px 0 0 3px; }
+.git-scope-btn:last-of-type  { border-radius: 0 3px 3px 0; border-left: none; }
+.git-scope-btn.active { background: #1a2840; border-color: #334466; color: #88aadd; }
+.git-scope-btn:disabled { opacity: 0.35; cursor: default; }
 .git-restore-btn {
   font-size: 10px; padding: 2px 6px;
   background: #1a2840; border: 1px solid #334466; border-radius: 3px;

frontend/index.html

@@ -449,8 +449,14 @@
 
       <!-- History section -->
       <div class="git-section" style="flex:1">
-        <label class="git-section-title">Commit history</label>
-        <div id="git-log-list" style="max-height:320px;overflow-y:auto;font-size:11px;display:flex;flex-direction:column;gap:1px"></div>
+        <div style="display:flex;align-items:center;justify-content:space-between">
+          <label class="git-section-title" id="git-log-title">Commit history</label>
+          <div style="display:flex;gap:2px">
+            <button id="btn-git-log-diagram" class="git-scope-btn active" title="Show commits for current diagram only">This diagram</button>
+            <button id="btn-git-log-all"     class="git-scope-btn"        title="Show all commits">All</button>
+          </div>
+        </div>
+        <div id="git-log-list" style="max-height:300px;overflow-y:auto;font-size:11px;display:flex;flex-direction:column;gap:1px"></div>
       </div>
 
     </div>

frontend/js/api.js

@@ -62,7 +62,7 @@ const api = {
   },
   git: {
     status:  ()                             => apiFetch("/git/status"),
-    log:     ()                             => apiFetch("/git/log"),
+    log:     (diagram_id)                   => apiFetch(diagram_id != null ? `/git/log?diagram_id=${diagram_id}` : "/git/log"),
     commit:  (message, diagram_id)          => apiFetch("/git/commit",  { method: "POST", headers: { "Content-Type": "application/json" }, body: JSON.stringify({ message, diagram_id: diagram_id ?? null }) }),
     push:    ()                             => apiFetch("/git/push",    { method: "POST" }),
     history: (hash)                         => apiFetch(`/git/history/${hash}`),

frontend/js/app.js

@@ -2024,8 +2024,26 @@ class WiringApp {
       commitBtn._gitBound = true;
       commitBtn.addEventListener("click", () => this._gitCommit());
       document.getElementById("btn-git-push").addEventListener("click", () => this._gitPush());
+
+      // History scope toggle
+      const btnDiagram = document.getElementById("btn-git-log-diagram");
+      const btnAll     = document.getElementById("btn-git-log-all");
+      btnDiagram.addEventListener("click", () => {
+        btnDiagram.classList.add("active"); btnAll.classList.remove("active");
+        this._gitLoadLog();
+      });
+      btnAll.addEventListener("click", () => {
+        btnAll.classList.add("active"); btnDiagram.classList.remove("active");
+        this._gitLoadLog();
+      });
     }
 
+    // Default scope: "this diagram" if one is open, else "all"
+    const hasDiagram = !!this.diagramId;
+    document.getElementById("btn-git-log-diagram").classList.toggle("active", hasDiagram);
+    document.getElementById("btn-git-log-all").classList.toggle("active", !hasDiagram);
+    document.getElementById("btn-git-log-diagram").disabled = !hasDiagram;
+
     await this._gitRefresh();
   }
 
@@ -2051,9 +2069,13 @@ class WiringApp {
   async _gitLoadLog() {
     const list = document.getElementById("git-log-list");
     if (!list) return;
+    const diagramScope = document.getElementById("btn-git-log-diagram")?.classList.contains("active");
+    const diagramId = diagramScope && this.diagramId ? this.diagramId : null;
+    const title = document.getElementById("git-log-title");
+    if (title) title.textContent = diagramId ? "History — this diagram" : "History — all commits";
     list.innerHTML = '<div style="color:#556;padding:4px">Loading…</div>';
     try {
-      const entries = await api.git.log();
+      const entries = await api.git.log(diagramId);
       if (!entries.length) {
         list.innerHTML = '<div style="color:#556;padding:4px">No commits yet</div>';
         return;