diff --git a/tests/test_issue4622_tool_card_restore_guard.py b/tests/test_issue4622_tool_card_restore_guard.py
new file mode 100644
index 00000000..299e4450
--- /dev/null
+++ b/tests/test_issue4622_tool_card_restore_guard.py
@@ -0,0 +1,191 @@
+"""Behavioural regression guard for issue #4622: in the Transparent Stream /
+Worklog view, restored (settled / reloaded) tool-call cards must keep showing
+the FULL terminal output with a working expand control, and patch/edit cards
+must still render their diff body.
+
+This drives the ACTUAL ``buildToolCard`` and ``_anchorSceneToolCallFromRow``
+from ``static/ui.js`` via node (not a regex over the source). The reload path
+rebuilds a tool card from a persisted ``activity_scene_v1`` row through
+``_anchorSceneToolCallFromRow`` and then ``buildToolCard``; this pins that the
+reconstructed card:
+
+  * produces a "Show more" expand button for output over the 800-char cap, with
+    the FULL output carried in ``data-full=`` (so the inline ``_toggleToolDiff``
+    expand handler can reveal it), and
+  * renders a ``diff-block`` for patch/edit snippets.
+
+#4622 was reported as a regression after the v0.51.547-.560 wave (which actually
+*restored* this activity via #4539/#4587). Independent reproduction on master was
+negative; this test is the permanent guard so the restore path cannot silently
+lose full output / expand / diff again.
+"""
+import json
+import shutil
+import subprocess
+from pathlib import Path
+
+import pytest
+
+REPO_ROOT = Path(__file__).parent.parent.resolve()
+UI_JS_PATH = REPO_ROOT / "static" / "ui.js"
+
+NODE = shutil.which("node")
+pytestmark = pytest.mark.skipif(NODE is None, reason="node not on PATH")
+
+
+_DRIVER_SRC = r"""
+const fs = require('fs');
+const src = fs.readFileSync(process.argv[2], 'utf8');
+
+function extractFunc(name) {
+  const re = new RegExp('function\\s+' + name + '\\s*\\(');
+  const start = src.search(re);
+  if (start < 0) throw new Error(name + ' not found');
+  let i = src.indexOf('{', start);
+  let depth = 1; i++;
+  while (depth > 0 && i < src.length) {
+    if (src[i] === '{') depth++;
+    else if (src[i] === '}') depth--;
+    i++;
+  }
+  return src.slice(start, i);
+}
+
+// Minimal DOM stub. buildToolCard does createElement('div') then assigns
+// row.innerHTML = `...` as a string; we capture that string and assert on it.
+function makeEl() {
+  return {
+    _class: '', innerHTML: '', _attrs: {},
+    get className(){return this._class;}, set className(v){this._class=v;},
+    dataset: {},
+    setAttribute(k,v){this._attrs[k]=String(v);},
+    getAttribute(k){return this._attrs[k];},
+    removeAttribute(k){delete this._attrs[k];},
+    appendChild(){}, querySelector(){return null;}, closest(){return null;},
+  };
+}
+global.document = { createElement: () => makeEl() };
+global.window = {};
+
+// Escaping + trivial label/icon helpers that buildToolCard references but which
+// are orthogonal to the output/diff behaviour under test.
+global.esc = (s)=>String(s==null?'':s).replace(/&/g,'&amp;').replace(/</g,'&lt;').replace(/>/g,'&gt;').replace(/"/g,'&quot;');
+global.li = (n)=>'<i data-lucide="'+n+'"></i>';
+global.toolIcon = ()=>'<i></i>';
+global._toolActionLabelText = (tc)=>String(tc&&tc.name||'tool');
+global._toolDisplayName = (tc)=>String(tc&&tc.name||'tool');
+global._toolDisclosureIdentity = ()=>'';
+global._toolCardPreviewText = ()=>'';
+global._formatToolArgPreview = ()=>'';
+global._toolDetailLeadText = ()=>'';
+global._toolDetailLeadLabel = ()=>'Shell';
+global._isMemorySave = ()=>false;
+global._isSkillUpdate = ()=>false;
+
+// Real functions under test (extracted from the live source):
+for (const fn of ['_snippetLooksLikeDiff','_colorDiffLines','_toolActionKind',
+                  '_toolCardAllowsDetail','buildToolCard','_anchorSceneToolCallFromRow']) {
+  eval(extractFunc(fn));
+}
+
+const mode = process.argv[3];
+const payload = JSON.parse(process.argv[4]);
+let html;
+if (mode === 'direct') {
+  // Build a card directly from a live tool-call object.
+  html = buildToolCard(payload).innerHTML;
+} else if (mode === 'restored') {
+  // Simulate the reload/settled path: reconstruct the tool call from a persisted
+  // activity_scene_v1 row, then build the card from THAT.
+  const tc = _anchorSceneToolCallFromRow(payload, {settled:true});
+  const card = buildToolCard(tc);
+  html = card.innerHTML;
+  process.stdout.write(JSON.stringify({
+    html,
+    snippet_len: (tc.snippet||'').length,
+  }));
+  return;
+} else {
+  throw new Error('unknown mode ' + mode);
+}
+process.stdout.write(JSON.stringify({ html, snippet_len: (payload.snippet||'').length }));
+"""
+
+
+@pytest.fixture(scope="module")
+def driver_path(tmp_path_factory):
+    p = tmp_path_factory.mktemp("tool_card_restore_driver") / "driver.js"
+    p.write_text(_DRIVER_SRC, encoding="utf-8")
+    return str(p)
+
+
+def _run(driver_path, mode, payload):
+    result = subprocess.run(
+        [NODE, driver_path, str(UI_JS_PATH), mode, json.dumps(payload)],
+        capture_output=True, text=True, timeout=30,
+    )
+    if result.returncode != 0:
+        raise RuntimeError(f"node driver failed: {result.stderr}")
+    return json.loads(result.stdout)
+
+
+# A terminal output well over buildToolCard's 800-char display cap.
+LONG_SHELL_OUTPUT = "result line {}\n".format("x" * 20) * 120  # ~> 800 chars
+DIFF_SNIPPET = "@@ -1,3 +1,4 @@\n context\n-old line\n+new line\n+added line\n"
+
+
+class TestRestoredToolCardKeepsFullOutputAndExpand:
+    """#4622 symptom 1: restored terminal cards must keep full output + expand."""
+
+    def test_long_output_direct_card_has_expand_with_full_snippet(self, driver_path):
+        tc = {"name": "terminal", "args": {"command": "ls -R /"},
+              "snippet": LONG_SHELL_OUTPUT, "done": True}
+        out = _run(driver_path, "direct", tc)
+        assert "tool-card-more" in out["html"], (
+            "a terminal output over the display cap must render a Show-more expand button"
+        )
+        # The inline _toggleToolDiff handler reveals data-full; it must be
+        # present (it carries the full output, not the truncated preview).
+        assert "data-full=" in out["html"]
+
+    def test_restored_scene_terminal_card_stays_expandable(self, driver_path):
+        """The reload/settled path reconstructs the card from a persisted scene
+        row; it must still be expandable with the full output recovered."""
+        scene_row = {
+            "role": "tool", "status": "completed",
+            "tool": {"name": "terminal", "args": {"command": "ls -R /"}},
+            "payload": {"output": LONG_SHELL_OUTPUT},
+        }
+        out = _run(driver_path, "restored", scene_row)
+        assert out["snippet_len"] >= len(LONG_SHELL_OUTPUT) - 4, (
+            "restored tool call must recover the FULL output snippet from the "
+            f"persisted scene row (got {out['snippet_len']} vs {len(LONG_SHELL_OUTPUT)})"
+        )
+        assert "tool-card-more" in out["html"], (
+            "restored terminal card must still render the Show-more expand control"
+        )
+
+
+class TestRestoredPatchCardRendersDiff:
+    """#4622 symptom 2: restored patch/edit cards must render the diff body."""
+
+    def test_direct_patch_card_renders_diff_block(self, driver_path):
+        tc = {"name": "patch", "args": {"path": "foo.py"},
+              "snippet": DIFF_SNIPPET, "is_diff": True, "done": True}
+        out = _run(driver_path, "direct", tc)
+        assert "diff-block" in out["html"]
+
+    def test_restored_scene_patch_card_renders_diff_block(self, driver_path):
+        scene_row = {
+            "role": "tool", "status": "completed",
+            "tool": {"name": "patch", "args": {"path": "foo.py"}},
+            "payload": {"output": DIFF_SNIPPET},
+        }
+        out = _run(driver_path, "restored", scene_row)
+        assert out["snippet_len"] >= len(DIFF_SNIPPET) - 4, (
+            "restored patch tool call must recover the full diff snippet"
+        )
+        assert "diff-block" in out["html"], (
+            "restored patch card must render the diff body (diff-block) from the "
+            "persisted scene snippet"
+        )