diff --git a/CHANGELOG.md b/CHANGELOG.md
index a9b27059..95553115 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -3,6 +3,12 @@
 
 ## [Unreleased]
 
+## [v0.51.633] — 2026-06-24 — Release WN (collapsed tool cards preview the result, not the call args)
+
+### Fixed
+
+- **A completed tool card's collapsed header now previews the tool's result instead of its call arguments.** For a finished tool, the one-line header showed the call args (e.g. `path=src/`) rather than what actually happened (e.g. `Found 3 matches`). Completed tools now surface a one-line result preview (from the tool's preview/snippet), suppressing JSON object/array blobs and capping length, while running tools and the args-preview fallback are unchanged. The preview is escaped on render (no XSS). Thanks @rodboev. (#4851, closes #4752)
+
 ## [v0.51.632] — 2026-06-24 — Release WM (new conversations use your configured default model)
 
 ### Fixed
diff --git a/static/ui.js b/static/ui.js
index 56f9f888..45252c98 100644
--- a/static/ui.js
+++ b/static/ui.js
@@ -12903,9 +12903,21 @@ function _formatToolArgPreview(args){
   const out=parts.join(' · ');
   return out.length>180?`${out.slice(0,177)}…`:out;
 }
+function _toolResultOneLiner(preview){
+  if(!preview) return '';
+  const first=preview.split('\n').find(l=>l.trim())||'';
+  const trimmed=first.trim();
+  if(!trimmed) return '';
+  if(trimmed[0]==='{') return '';
+  if(trimmed[0]==='['){try{JSON.parse(trimmed);return '';}catch(e){/* not JSON */}}
+  return trimmed.length>180?trimmed.slice(0,177)+'…':trimmed;
+}
 function _toolCardPreviewText(tc, displaySnippet){
   const explicitPreview=String(tc&&tc.preview||'').trim();
   if(tc&&tc.done===false&&explicitPreview) return explicitPreview;
+  const resultSource=explicitPreview||String(tc&&tc.snippet||'').trim();
+  const resultLine=_toolResultOneLiner(resultSource);
+  if(tc&&tc.done!==false&&resultLine) return resultLine;
   const argPreview=_formatToolArgPreview(tc&&tc.args);
   if(argPreview) return argPreview;
   if(tc&&tc.done===false) return 'Running';
diff --git a/tests/test_issue1824_cli_patch_diff_rendering.py b/tests/test_issue1824_cli_patch_diff_rendering.py
index 7e51d750..ad6051a2 100644
--- a/tests/test_issue1824_cli_patch_diff_rendering.py
+++ b/tests/test_issue1824_cli_patch_diff_rendering.py
@@ -112,6 +112,7 @@ def test_rendered_apply_patch_tool_card_html_contains_diff_lines():
         "_toolArgPreviewValue",
         "_toolArgPreviewKeyIsHidden",
         "_formatToolArgPreview",
+        "_toolResultOneLiner",
         "_toolCardPreviewText",
         # #3336: buildToolCard now wraps diff snippets via these helpers.
         "_snippetLooksLikeDiff",
diff --git a/tests/test_issue4658_transparent_collapsed_preview.py b/tests/test_issue4658_transparent_collapsed_preview.py
index c0aa224c..5401ef50 100644
--- a/tests/test_issue4658_transparent_collapsed_preview.py
+++ b/tests/test_issue4658_transparent_collapsed_preview.py
@@ -23,6 +23,7 @@ shims, and runs the same render path live streaming and persisted reload share
 (both go through _decorateTransparentEventRow(buildToolCard(tc))).
 """
 import json
+import re
 import shutil
 import subprocess
 from pathlib import Path
@@ -35,11 +36,77 @@ UI_JS_PATH = REPO_ROOT / "static" / "ui.js"
 NODE = shutil.which("node")
 pytestmark = pytest.mark.skipif(NODE is None, reason="node not on PATH")
 
+_FN_NAMES = [
+    '_toolDisplayName', '_toolActionKind', '_toolKindIcon', '_toolPathBasename',
+    '_decodeToolLabelEntities', '_redactToolTargetLabel', '_shortToolLabel', '_toolI18n',
+    '_toolTargetLabel', '_toolVisibleTargetLabel', '_toolCommandTitle', '_toolQueryTitle',
+    '_toolActionLabelText', '_toolArgPreviewValue', '_toolArgPreviewKeyIsHidden',
+    '_formatToolArgPreview', '_toolResultOneLiner', '_toolCardPreviewText', '_toolCardAllowsDetail',
+    '_toolDetailLeadLabel', '_toolDetailLeadText', '_toolShortName', '_transparentEventPreview',
+    '_transparentToolStatus', '_transparentToolSummary',
+    '_isMemorySave', '_isSkillUpdate', '_tcAction',
+    'buildToolCard', '_decorateTransparentEventRow',
+]
 
-_DRIVER_SRC = r"""
-const fs = require('fs');
-const src = fs.readFileSync(process.argv[2], 'utf8');
 
+def _function_source(src: str, name: str) -> str:
+    match = re.search(rf"function\s+{re.escape(name)}\s*\(", src)
+    if not match:
+        return ""
+    brace = src.find("{", match.end())
+    assert brace != -1, f"{name}() has no body"
+    depth = 1
+    i = brace + 1
+    in_string = None
+    escaped = False
+    in_line_comment = False
+    in_block_comment = False
+    while i < len(src) and depth:
+        ch = src[i]
+        nxt = src[i + 1] if i + 1 < len(src) else ""
+        if in_line_comment:
+            if ch == "\n":
+                in_line_comment = False
+            i += 1
+            continue
+        if in_block_comment:
+            if ch == "*" and nxt == "/":
+                in_block_comment = False
+                i += 2
+                continue
+            i += 1
+            continue
+        if in_string:
+            if escaped:
+                escaped = False
+            elif ch == "\\":
+                escaped = True
+            elif ch == in_string:
+                in_string = None
+            i += 1
+            continue
+        if ch == "/" and nxt == "/":
+            in_line_comment = True
+            i += 2
+            continue
+        if ch == "/" and nxt == "*":
+            in_block_comment = True
+            i += 2
+            continue
+        if ch in "'\"`":
+            in_string = ch
+            i += 1
+            continue
+        if ch == "{":
+            depth += 1
+        elif ch == "}":
+            depth -= 1
+        i += 1
+    assert depth == 0, f"{name}() body did not close"
+    return src[match.start():i]
+
+
+_DRIVER_TEMPLATE = r"""
 // ── Minimal DOM shims (enough for buildToolCard + _decorateTransparentEventRow)
 function makeEl(tag){
   const el = {
@@ -61,7 +128,6 @@ function makeEl(tag){
     get innerHTML(){return el._html;},
     set innerHTML(v){
       el._html=String(v);
-      // Parse just the spans we assert on out of the template buildToolCard emits.
       el.children=[];
       const mk=(cls,text)=>{const c=makeEl('span'); c._classes=new Set(cls.split(' ').filter(Boolean)); c.textContent=text; c.parentNode=el; el.children.push(c);};
       const grab=(cls)=>{const re=new RegExp('<span class="'+cls.replace(/[-]/g,'\\-')+'">([\\s\\S]*?)<\\/span>'); const m=el._html.match(re); return m?m[1]:null;};
@@ -70,7 +136,6 @@ function makeEl(tag){
       const preview=grab('tool-card-preview');
       if(preview!==null) mk('tool-card-preview', preview);
       const header=makeEl('div'); header._classes=new Set(['tool-card-header']);
-      // re-home the parsed spans under a header element so querySelector('.tool-card-header') works
       header.children=el.children.slice(); header.children.forEach(c=>c.parentNode=header);
       const card=makeEl('div'); card._classes=new Set(['tool-card']); card.appendChild(header);
       el.children=[card]; el.firstChild=card;
@@ -87,8 +152,8 @@ function makeEl(tag){
   return el;
 }
 
-global.document = { createElement: (t)=>makeEl(t), querySelectorAll:()=>[], querySelector:()=>null };
-global.window = {};
+global.document = { createElement: (t)=>makeEl(t), querySelectorAll:()=>[], querySelector:()=>null, addEventListener:()=>{}, removeEventListener:()=>{} };
+global.window = { addEventListener:()=>{}, removeEventListener:()=>{} };
 global.CSS = { escape: s=>s };
 global.t = undefined;
 global.li = () => '<svg></svg>';
@@ -100,36 +165,10 @@ global._attachCopyButton = () => {};
 global._attachProgressBar = () => {};
 global._wireTransparentHeaderToggle = () => {};
 global._transparentToolDetailHtml = () => '<div class="tool-card-detail"></div>';
-// _toolDisclosureIdentity pulls in worklog hashing helpers irrelevant to the
-// collapsed-preview assertion; stub it (only feeds a data- attribute).
 global._toolDisclosureIdentity = () => '';
 
-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);
-}
-// helpers buildToolCard / decorate depend on — eval'd at TOP LEVEL (a function
-// declaration eval'd inside a callback would be scoped to that callback and
-// lost, so collect all sources and eval them once here).
-var _FN_NAMES=[
- '_toolDisplayName','_toolActionKind','_toolKindIcon','_toolPathBasename',
- '_decodeToolLabelEntities','_redactToolTargetLabel','_shortToolLabel','_toolI18n',
- '_toolTargetLabel','_toolVisibleTargetLabel','_toolCommandTitle','_toolQueryTitle',
- '_toolActionLabelText','_toolArgPreviewValue','_toolArgPreviewKeyIsHidden',
- '_formatToolArgPreview','_toolCardPreviewText','_toolCardAllowsDetail',
- '_toolDetailLeadLabel','_toolDetailLeadText','_toolShortName','_transparentEventPreview',
- '_transparentToolStatus','_transparentToolSummary',
- '_isMemorySave','_isSkillUpdate','_tcAction',
- 'buildToolCard','_decorateTransparentEventRow',
-];
-var _FN_SRC='';
-for(var _i=0;_i<_FN_NAMES.length;_i++){
-  try{ _FN_SRC+=extractFunc(_FN_NAMES[_i])+'\n'; }catch(e){ /* optional helper absent */ }
-}
-eval(_FN_SRC);
+// ── EXTRACTED_FUNCTIONS placeholder (replaced by Python) ──
+%%EXTRACTED_FUNCTIONS%%
 
 function previewFor(tc){
   const row=_decorateTransparentEventRow(buildToolCard(tc),{
@@ -142,7 +181,7 @@ function previewFor(tc){
   return { preview: preview?preview.textContent:null, name: name?name.textContent:null };
 }
 
-const cases = JSON.parse(process.argv[3]);
+const cases = JSON.parse(process.argv[2]);
 const out = {};
 for(const [key,tc] of Object.entries(cases)) out[key]=previewFor(tc);
 process.stdout.write(JSON.stringify(out));
@@ -162,10 +201,16 @@ CASES = {
 
 @pytest.fixture(scope="module")
 def results(tmp_path_factory):
+    ui_src = UI_JS_PATH.read_text(encoding="utf-8")
+    extracted = "\n".join(
+        _function_source(ui_src, name) for name in _FN_NAMES
+        if _function_source(ui_src, name)
+    )
+    driver_src = _DRIVER_TEMPLATE.replace("%%EXTRACTED_FUNCTIONS%%", extracted)
     driver = tmp_path_factory.mktemp("t4658") / "driver.js"
-    driver.write_text(_DRIVER_SRC, encoding="utf-8")
+    driver.write_text(driver_src, encoding="utf-8")
     proc = subprocess.run(
-        [NODE, str(driver), str(UI_JS_PATH), json.dumps(CASES)],
+        [NODE, str(driver), json.dumps(CASES)],
         capture_output=True, text=True, timeout=30,
     )
     if proc.returncode != 0:
diff --git a/tests/test_issue4752_collapsed_card_shows_result.py b/tests/test_issue4752_collapsed_card_shows_result.py
new file mode 100644
index 00000000..c1ec8e9d
--- /dev/null
+++ b/tests/test_issue4752_collapsed_card_shows_result.py
@@ -0,0 +1,203 @@
+"""Regression tests for issue #4752 — collapsed tool card shows call result, not args.
+
+Extracts _toolResultOneLiner, _toolCardPreviewText, and _formatToolArgPreview from
+static/ui.js by line range and runs them via Node.js to verify the fix.
+
+Before the fix, _toolCardPreviewText always fell through to argPreview for completed
+tools, so 'Found 3 matches' would show as 'path=src/' in the collapsed header.
+"""
+import json
+import os
+import re
+import shutil
+import subprocess
+import tempfile
+
+import pytest
+
+NODE = shutil.which("node")
+pytestmark = pytest.mark.skipif(NODE is None, reason="node not on PATH")
+
+UI_JS = os.path.join(os.path.dirname(__file__), '..', 'static', 'ui.js')
+
+
+def _extract_js_block():
+    """Extract the tool-card preview functions from ui.js by finding their definition range."""
+    lines = open(UI_JS, encoding='utf-8').readlines()
+
+    # Find start line of _toolArgPreviewValue (the earliest dependency)
+    start_line = None
+    for i, line in enumerate(lines):
+        if re.search(r'^function _toolArgPreviewValue\(', line):
+            start_line = i
+            break
+    if start_line is None:
+        raise AssertionError("_toolArgPreviewValue not found in ui.js")
+
+    # Find end line of _toolCardPreviewText (the last function we need)
+    # It ends at the function _toolCardAllowsDetail that follows it
+    end_line = None
+    for i in range(start_line, len(lines)):
+        if re.search(r'^function _toolCardAllowsDetail\(', lines[i]):
+            end_line = i
+            break
+    if end_line is None:
+        raise AssertionError("_toolCardAllowsDetail (end sentinel) not found in ui.js")
+
+    return "".join(lines[start_line:end_line])
+
+
+def _run_js(js_body, *args):
+    """Run a Node.js snippet with optional JSON arguments, return stdout."""
+    fn_defs = _extract_js_block()
+    js_code = fn_defs + "\n" + js_body
+    tf = tempfile.NamedTemporaryFile(mode='w', suffix='.js', delete=False, encoding='utf-8')
+    tf.write(js_code)
+    tf.close()
+    try:
+        result = subprocess.run(
+            [NODE, tf.name] + [json.dumps(a) for a in args],
+            capture_output=True, text=True, timeout=30
+        )
+        if result.returncode != 0:
+            raise RuntimeError(f"node error: {result.stderr}")
+        return result.stdout
+    finally:
+        os.unlink(tf.name)
+
+
+def _preview_text(tc):
+    """Call _toolCardPreviewText(tc) via Node.js."""
+    return _run_js(
+        "var tc=JSON.parse(process.argv[2]);\n"
+        "process.stdout.write(String(_toolCardPreviewText(tc)));\n",
+        tc
+    )
+
+
+def _result_one_liner(preview):
+    """Call _toolResultOneLiner(preview) via Node.js."""
+    return _run_js(
+        "var p=JSON.parse(process.argv[2]);\n"
+        "process.stdout.write(String(_toolResultOneLiner(p)));\n",
+        preview
+    )
+
+
+class TestToolResultOneLiner:
+    """Unit tests for the _toolResultOneLiner helper."""
+
+    def test_empty_string_returns_empty(self):
+        assert _result_one_liner("") == ""
+
+    def test_plain_text_returned(self):
+        assert _result_one_liner("Found 3 matches") == "Found 3 matches"
+
+    def test_json_object_suppressed(self):
+        assert _result_one_liner('{"key":"val"}') == ""
+
+    def test_json_array_suppressed(self):
+        assert _result_one_liner('[1,2,3]') == ""
+
+    def test_bracket_prefixed_non_json_shown(self):
+        assert _result_one_liner('[INFO] 3 files created') == "[INFO] 3 files created"
+
+    def test_multiline_collapses_to_first_nonempty_line(self):
+        assert _result_one_liner("Line 1\nLine 2\nLine 3") == "Line 1"
+
+    def test_leading_blank_lines_skipped(self):
+        assert _result_one_liner("\n\nActual result") == "Actual result"
+
+    def test_truncation_at_180_chars(self):
+        long_line = "x" * 200
+        result = _result_one_liner(long_line)
+        assert result.endswith("…")
+        # 177 ASCII chars + 1 ellipsis character = 178 chars total
+        assert len(result) == 178
+
+    def test_short_line_not_truncated(self):
+        line = "x" * 180
+        result = _result_one_liner(line)
+        assert len(result) == 180
+        assert not result.endswith("…")
+
+
+class TestToolCardPreviewText:
+    """Integration tests for the updated _toolCardPreviewText function."""
+
+    def test_result_wins_on_completion(self):
+        """Completed tool with both preview and args returns the preview result."""
+        tc = {"done": True, "preview": "Found 3 matches", "args": {"path": "src/"}}
+        assert _preview_text(tc) == "Found 3 matches"
+
+    def test_args_fallback_when_no_preview(self):
+        """Completed tool without preview falls back to arg preview."""
+        tc = {"done": True, "preview": "", "args": {"path": "src/"}}
+        result = _preview_text(tc)
+        assert "path" in result
+        assert "src" in result
+
+    def test_json_preview_suppressed_falls_through_to_args(self):
+        """JSON body in preview is suppressed; falls back to arg preview."""
+        tc = {"done": True, "preview": '{"key":"val"}', "args": {"path": "src/"}}
+        result = _preview_text(tc)
+        # JSON suppressed, so falls through to arg preview
+        assert result != '{"key":"val"}'
+        assert "path" in result or "src" in result
+
+    def test_array_preview_suppressed_falls_through_to_args(self):
+        """Array body in preview is suppressed; falls back to arg preview."""
+        tc = {"done": True, "preview": "[1,2,3]", "args": {"path": "src/"}}
+        result = _preview_text(tc)
+        assert result != "[1,2,3]"
+        assert "path" in result or "src" in result
+
+    def test_multiline_preview_collapses_to_first_line(self):
+        """Multiline preview collapses to first non-empty line."""
+        tc = {"done": True, "preview": "Line 1\nLine 2\nLine 3", "args": {}}
+        assert _preview_text(tc) == "Line 1"
+
+    def test_running_preview_unchanged(self):
+        """Running tool (done===false) returns the explicit preview unchanged."""
+        tc = {"done": False, "preview": "Searching...", "args": {"path": "src/"}}
+        assert _preview_text(tc) == "Searching..."
+
+    def test_long_preview_truncated(self):
+        """Single-line preview >180 chars is truncated with ellipsis."""
+        long_preview = "x" * 200
+        tc = {"done": True, "preview": long_preview, "args": {}}
+        result = _preview_text(tc)
+        assert result.endswith("…")
+        assert len(result) == 178  # 177 chars + ellipsis
+
+    def test_no_args_no_preview_returns_completed(self):
+        """Completed tool with no args and no preview returns 'Completed'."""
+        tc = {"done": True, "preview": "", "args": {}}
+        assert _preview_text(tc) == "Completed"
+
+    def test_error_state_returns_failed(self):
+        """Error tool with no preview or args returns 'Failed'."""
+        tc = {"done": True, "is_error": True, "preview": "", "args": {}}
+        assert _preview_text(tc) == "Failed"
+
+    def test_running_no_preview_returns_running(self):
+        """Running tool with no preview returns 'Running'."""
+        tc = {"done": False, "preview": "", "args": {}}
+        assert _preview_text(tc) == "Running"
+
+    def test_snippet_fallback_on_cold_load(self):
+        """Cold-loaded tool with result in snippet (no preview) uses snippet."""
+        tc = {"done": True, "preview": "", "snippet": "Found 3 matches", "args": {"path": "src/"}}
+        assert _preview_text(tc) == "Found 3 matches"
+
+    def test_error_with_text_snippet_shows_message(self):
+        """Error tool with a plain-text snippet shows the error message, not 'Failed'."""
+        tc = {"done": True, "is_error": True, "preview": "", "snippet": "Permission denied", "args": {}}
+        assert _preview_text(tc) == "Permission denied"
+
+    def test_snippet_json_suppressed(self):
+        """Cold-loaded tool with JSON in snippet falls through to args."""
+        tc = {"done": True, "preview": "", "snippet": '{"key":"val"}', "args": {"path": "src/"}}
+        result = _preview_text(tc)
+        assert result != '{"key":"val"}'
+        assert "path" in result or "src" in result
diff --git a/tests/test_tool_card_preview_summary.py b/tests/test_tool_card_preview_summary.py
index ca9010b8..bb2aa307 100644
--- a/tests/test_tool_card_preview_summary.py
+++ b/tests/test_tool_card_preview_summary.py
@@ -21,24 +21,14 @@ 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);
+const lines = fs.readFileSync(process.argv[2], 'utf8').split('\n');
+let startIdx = -1, endIdx = lines.length;
+for (let i = 0; i < lines.length; i++) {
+  if (/^function _toolArgPreviewValue\(/.test(lines[i]) && startIdx < 0) startIdx = i;
+  if (/^function _toolCardAllowsDetail\(/.test(lines[i])) { endIdx = i; break; }
 }
-eval(extractFunc('_toolArgPreviewValue'));
-eval(extractFunc('_toolArgPreviewKeyIsHidden'));
-eval(extractFunc('_formatToolArgPreview'));
-eval(extractFunc('_toolCardPreviewText'));
+if (startIdx < 0) throw new Error('_toolArgPreviewValue not found');
+eval(lines.slice(startIdx, endIdx).join('\n'));
 let buf = '';
 process.stdin.on('data', c => { buf += c; });
 process.stdin.on('end', () => {