diff --git a/static/css/cookbook-research-memory-settings.css b/static/css/cookbook-research-memory-settings.css
index 67f425dae..9f6df2679 100644
--- a/static/css/cookbook-research-memory-settings.css
+++ b/static/css/cookbook-research-memory-settings.css
@@ -1171,6 +1171,38 @@ details.hwfit-serve-advanced label:has(.hwfit-sf[data-field="vllm_kv_cache_dtype
   overflow-y: auto;
   overflow-x: hidden;
 }
+/* Build provenance at the bottom of the sidebar. The nav above it takes the
+   free space, so this needs no absolute positioning to sit at the bottom.
+   `[hidden]` needs restating: an author `display` rule outranks the UA
+   stylesheet's [hidden] rule, so the attribute alone would not hide it. */
+.settings-sidebar-build {
+  display: flex;
+  min-width: 0;
+  flex: 0 0 auto;
+  flex-direction: column;
+  gap: 1px;
+  margin-top: 8px;
+  padding: 4px 12px 2px;
+  border-top: 1px solid var(--border);
+  font-size: 9px;
+  color: color-mix(in srgb, var(--fg) 45%, transparent);
+}
+.settings-sidebar-build[hidden] {
+  display: none;
+}
+/* Same treatment as the "Admin" group label this sits under. */
+.settings-sidebar-build-version {
+  font-weight: 600;
+  letter-spacing: 1px;
+  text-transform: uppercase;
+}
+.settings-sidebar-build-commit {
+  overflow: hidden;
+  font-variant-numeric: tabular-nums;
+  text-overflow: ellipsis;
+  white-space: nowrap;
+  opacity: 0.75;
+}
 .settings-nav-search-wrap {
   position: relative;
   margin: 0 0 8px;
@@ -1326,6 +1358,9 @@ body.settings-sidebar-resize-active {
 .settings-sidebar.settings-sidebar-collapsed .settings-sidebar-content {
   display: none;
 }
+.settings-sidebar.settings-sidebar-collapsed .settings-sidebar-build {
+  display: none;
+}
 .settings-sidebar.settings-sidebar-collapsed .settings-sidebar-resize-handle {
   display: none;
 }
@@ -1356,7 +1391,8 @@ body.settings-sidebar-resize-active {
 
   .settings-nav-search-wrap,
   .settings-sidebar-resize-handle,
-  .settings-sidebar-toggle {
+  .settings-sidebar-toggle,
+  .settings-sidebar-build {
     display: none;
   }
 
@@ -1384,7 +1420,8 @@ body.settings-sidebar-resize-active {
 
   .settings-nav-search-wrap,
   .settings-sidebar-resize-handle,
-  .settings-sidebar-toggle {
+  .settings-sidebar-toggle,
+  .settings-sidebar-build {
     display: none;
   }
 }
diff --git a/static/index.html b/static/index.html
index dcae7008b..9e537d027 100644
--- a/static/index.html
+++ b/static/index.html
@@ -1532,6 +1532,15 @@
             <span>System</span>
           </button>
           </div>
+
+          <!-- Build provenance, pinned below the scrolling nav so it stays at
+               the bottom-left of the panel: the version this build registers
+               and the commit the running process actually loaded. Populated
+               from /api/version; stays hidden until that answers. -->
+          <div class="settings-sidebar-build admin-only" id="settings-sidebar-build" hidden>
+            <span class="settings-sidebar-build-version" id="settings-sidebar-build-version"></span>
+            <span class="settings-sidebar-build-commit" id="settings-sidebar-build-commit"></span>
+          </div>
         </div>
         <div class="settings-panels">
 
diff --git a/static/js/settings/sidebar.js b/static/js/settings/sidebar.js
index 7e1a34aeb..f4787a40f 100644
--- a/static/js/settings/sidebar.js
+++ b/static/js/settings/sidebar.js
@@ -121,10 +121,88 @@ export function setSettingsSidebarWidth(modalEl, width, options = {}) {
   return next;
 }
 
+/* ── Build provenance ──
+   The bottom-left of the panel answers "which build am I actually looking
+   at": the version this build registers and the commit its process loaded.
+   Both come from /api/version, which resolves the commit once at import via
+   `git rev-parse HEAD` and reports the string "unknown" when it cannot — a
+   read-only Docker tree with no .git, for instance. */
+const BUILD_COMMIT_SHORT_LEN = 8;
+const BUILD_UNKNOWN = 'unknown';
+const BUILD_COMMIT_SHA = /^[0-9a-f]{7,64}$/i;
+
+function buildField(value) {
+  const text = String(value ?? '').trim();
+  return text && text.toLowerCase() !== BUILD_UNKNOWN ? text : '';
+}
+
+/** Turn an /api/version payload into the two sidebar lines, or null when it
+ *  carries nothing worth a footer. */
+export function formatSettingsBuildInfo(payload) {
+  const version = buildField(payload?.version);
+  const build = buildField(payload?.build);
+  const commit = buildField(payload?.source_commit);
+
+  const parts = [];
+  if (version) parts.push(`v${version}`);
+  // The preview harness versions itself separately from the public semver, so
+  // show both — but never the same number twice.
+  if (build && build !== version) parts.push(`build ${build}`);
+
+  // An ODYSSEUS_SOURCE_COMMIT override need not be a sha; leave those intact
+  // and let the CSS ellipsis deal with the width.
+  const commitLabel = BUILD_COMMIT_SHA.test(commit)
+    ? commit.slice(0, BUILD_COMMIT_SHORT_LEN).toLowerCase()
+    : commit;
+
+  if (!parts.length && !commitLabel) return null;
+
+  return {
+    versionLabel: parts.join(' \u00b7 '),
+    commitLabel,
+    commitTitle: commit,
+  };
+}
+
+function paintSettingsBuildInfo(modalEl, info) {
+  const host = modalEl?.querySelector('#settings-sidebar-build');
+  if (!host) return;
+
+  const versionEl = host.querySelector('#settings-sidebar-build-version');
+  const commitEl = host.querySelector('#settings-sidebar-build-commit');
+
+  if (!info) {
+    host.hidden = true;
+    return;
+  }
+
+  if (versionEl) versionEl.textContent = info.versionLabel;
+  if (commitEl) {
+    commitEl.textContent = info.commitLabel;
+    // The short hash is what fits; keep the full one reachable on hover.
+    if (info.commitTitle) commitEl.title = info.commitTitle;
+  }
+
+  host.hidden = false;
+}
+
+async function loadSettingsBuildInfo(modalEl) {
+  try {
+    const res = await fetch('/api/version', { credentials: 'same-origin' });
+    if (!res.ok) return;
+    paintSettingsBuildInfo(modalEl, formatSettingsBuildInfo(await res.json()));
+  } catch {
+    // Provenance is informational: a failed probe leaves the footer hidden
+    // rather than putting an error in the middle of the settings nav.
+  }
+}
+
 export function bindSettingsSidebar(modalEl) {
   if (!modalEl || _bound.has(modalEl)) return;
   _bound.add(modalEl);
 
+  loadSettingsBuildInfo(modalEl);
+
   const sidebar = modalEl.querySelector('.settings-sidebar');
   const handle = modalEl.querySelector('#settings-sidebar-resize-handle');
   const toggle = modalEl.querySelector('#settings-sidebar-toggle');
diff --git a/tests/test_settings_sidebar_build_provenance.py b/tests/test_settings_sidebar_build_provenance.py
new file mode 100644
index 000000000..c360545c6
--- /dev/null
+++ b/tests/test_settings_sidebar_build_provenance.py
@@ -0,0 +1,232 @@
+"""The settings sidebar footer that names the running build.
+
+The admin panel had no way to answer "which build is this?" from the UI: the
+version and the source commit were only reachable by hand-querying
+``/api/version``. A footer pinned under the sidebar nav now shows the version
+the build registers plus the commit its process loaded.
+
+Three things can break independently, so each is covered on its own:
+
+* ``formatSettingsBuildInfo`` decides what the two lines say, including what
+  to do with the ``"unknown"`` the backend reports when it cannot resolve a
+  commit. That is real logic, so it is exercised in node against the shipped
+  module rather than asserted on as text.
+* the footer's *position* is the requirement — below the scrolling nav, inside
+  the sidebar. Only the markup's structure records that.
+* the layouts that have no bottom-left to write in (the collapsed rail, the
+  narrow tab rail) must hide it, and the ``[hidden]`` attribute only works
+  here because the CSS restates it against the element's own ``display`` rule.
+"""
+
+import json
+import re
+import shutil
+import subprocess
+from pathlib import Path
+
+import pytest
+
+
+ROOT = Path(__file__).resolve().parents[1]
+INDEX_HTML = (ROOT / "static" / "index.html").read_text(encoding="utf-8")
+SIDEBAR_CSS = (
+    ROOT / "static" / "css" / "cookbook-research-memory-settings.css"
+).read_text(encoding="utf-8")
+
+requires_node = pytest.mark.skipif(
+    not shutil.which("node"), reason="node binary not on PATH"
+)
+
+
+def _format_build_info(payload):
+    """Run the shipped formatter over one payload and return its result."""
+    source = (
+        "import { formatSettingsBuildInfo } from "
+        "'./static/js/settings/sidebar.js';\n"
+        f"console.log(JSON.stringify(formatSettingsBuildInfo({json.dumps(payload)})));\n"
+    )
+    result = subprocess.run(
+        ["node", "--input-type=module", "-e", source],
+        cwd=ROOT,
+        check=True,
+        capture_output=True,
+        text=True,
+    )
+    return json.loads(result.stdout)
+
+
+# ---------------------------------------------------------------------------
+# What the footer says
+# ---------------------------------------------------------------------------
+
+
+@requires_node
+def test_shows_registered_version_and_short_commit():
+    info = _format_build_info(
+        {
+            "version": "1.0.3",
+            "build": "0.20.19",
+            "source_commit": "8a28c5f9c0ffee1234567890abcdef1234567890",
+        }
+    )
+
+    assert info["versionLabel"] == "v1.0.3 · build 0.20.19"
+    assert info["commitLabel"] == "8a28c5f9"
+    # The short hash is what fits the sidebar; the full one stays on hover.
+    assert info["commitTitle"] == "8a28c5f9c0ffee1234567890abcdef1234567890"
+
+
+@requires_node
+def test_build_equal_to_version_is_not_printed_twice():
+    info = _format_build_info(
+        {"version": "1.0.3", "build": "1.0.3", "source_commit": "abcdef1234"}
+    )
+
+    assert info["versionLabel"] == "v1.0.3"
+
+
+@requires_node
+def test_unresolvable_commit_leaves_only_the_version():
+    """`/api/version` reports the string "unknown" when `git rev-parse` fails
+    — a read-only Docker tree with no `.git`. Printing it would be worse than
+    printing nothing."""
+    info = _format_build_info(
+        {"version": "1.0.3", "build": "unknown", "source_commit": "unknown"}
+    )
+
+    assert info["versionLabel"] == "v1.0.3"
+    assert info["commitLabel"] == ""
+    assert info["commitTitle"] == ""
+
+
+@requires_node
+def test_commit_only_build_still_gets_a_footer():
+    info = _format_build_info({"source_commit": "0123456789abcdef"})
+
+    assert info["versionLabel"] == ""
+    assert info["commitLabel"] == "01234567"
+
+
+@requires_node
+def test_non_sha_commit_override_is_left_intact():
+    """`ODYSSEUS_SOURCE_COMMIT` can be any string; truncating a tag to eight
+    characters would corrupt it, so only real hashes get shortened."""
+    info = _format_build_info(
+        {"version": "1.0.3", "source_commit": "release-2026-09-30"}
+    )
+
+    assert info["commitLabel"] == "release-2026-09-30"
+
+
+@requires_node
+@pytest.mark.parametrize(
+    "payload",
+    [
+        {},
+        {"version": "", "build": "", "source_commit": ""},
+        {"version": "unknown", "build": "unknown", "source_commit": "unknown"},
+    ],
+)
+def test_nothing_to_report_means_no_footer(payload):
+    assert _format_build_info(payload) is None
+
+
+# ---------------------------------------------------------------------------
+# Where the footer sits
+# ---------------------------------------------------------------------------
+
+
+def _settings_sidebar_markup():
+    start = INDEX_HTML.index('<div class="settings-sidebar">')
+    end = INDEX_HTML.index('<div class="settings-panels">', start)
+    return INDEX_HTML[start:end]
+
+
+def test_footer_is_the_last_thing_in_the_sidebar():
+    """The ask is bottom-left. The nav above it takes the free space, so the
+    footer lands at the bottom by being the sidebar's final child — and it has
+    to sit outside the nav's own scroll container to stay pinned there."""
+    sidebar = _settings_sidebar_markup()
+
+    nav_start = sidebar.index('<div class="settings-sidebar-content">')
+    footer_start = sidebar.index('id="settings-sidebar-build"')
+    assert nav_start < footer_start, "footer must come after the nav"
+
+    # Nothing but the footer between the nav's closing tag and the sidebar's.
+    tail = sidebar[footer_start:]
+    assert '<div class="settings-nav' not in tail
+    assert "settings-nav-item" not in tail
+
+
+def test_footer_carries_both_fields_and_is_admin_gated():
+    sidebar = _settings_sidebar_markup()
+    footer = sidebar[sidebar.index('id="settings-sidebar-build"') - 200:]
+
+    assert 'id="settings-sidebar-build-version"' in footer
+    assert 'id="settings-sidebar-build-commit"' in footer
+    # `.admin-only` is what syncAdminVisibility() hides for non-admins.
+    assert "settings-sidebar-build admin-only" in footer
+    # Hidden until /api/version answers, so no empty bordered strip appears.
+    assert re.search(r'id="settings-sidebar-build"[^>]*\bhidden\b', footer)
+
+
+# ---------------------------------------------------------------------------
+# When the footer must disappear
+# ---------------------------------------------------------------------------
+
+
+def _rule_body(selector, css=SIDEBAR_CSS):
+    match = re.search(
+        re.escape(selector) + r"\s*\{([^}]*)\}", css
+    )
+    assert match, f"no rule for {selector}"
+    return match.group(1)
+
+
+def test_hidden_attribute_is_restated_against_the_display_rule():
+    """`.settings-sidebar-build { display: flex }` is an author rule, so it
+    outranks the UA stylesheet's `[hidden]` rule. Without this the attribute
+    would not hide anything."""
+    assert "display: flex" in _rule_body(".settings-sidebar-build")
+    assert "display: none" in _rule_body(".settings-sidebar-build[hidden]")
+
+
+def test_collapsed_sidebar_hides_the_footer():
+    body = _rule_body(
+        ".settings-sidebar.settings-sidebar-collapsed .settings-sidebar-build"
+    )
+    assert "display: none" in body
+
+
+def test_both_narrow_tab_rail_layouts_hide_the_footer():
+    """At narrow widths the sidebar becomes a horizontal rail, where a stacked
+    footer has no bottom to sit at. Both the container query and the media
+    query switch to that layout, so both have to hide it."""
+    rails = re.findall(
+        r"([^{}]*\.settings-sidebar-build[^{}]*)\{\s*display:\s*none;\s*\}",
+        SIDEBAR_CSS,
+    )
+    tab_rail_rules = [r for r in rails if ".settings-sidebar-toggle" in r]
+    assert len(tab_rail_rules) == 2, tab_rail_rules
+
+
+# ---------------------------------------------------------------------------
+# The payload the footer reads
+# ---------------------------------------------------------------------------
+
+
+def test_api_version_reports_version_build_and_commit():
+    """The footer renders these three keys. `/api/version` is auth-exempt, so
+    it answers without a session — the same way the login page already reads
+    it."""
+    from fastapi.testclient import TestClient
+
+    from app import app
+
+    with TestClient(app) as client:
+        payload = client.get("/api/version").json()
+
+    assert set(payload) >= {"version", "build", "source_commit"}
+    # Absent values are reported as "unknown", never omitted or null, which is
+    # the case formatSettingsBuildInfo() filters on.
+    assert all(isinstance(payload[k], str) and payload[k] for k in payload)