diff --git a/manager/core/board.html b/manager/core/board.html
index ddcbc9e..fbc07dc 100644
--- a/manager/core/board.html
+++ b/manager/core/board.html
@@ -6,7 +6,10 @@
 <!-- The server rewrites this to "<project> · bench"; the view switcher keeps
      it in step. Project first — tab truncation eats the tail. -->
 <title>bench</title>
-<link rel="icon" href="data:image/svg+xml,<svg xmlns='http://www.w3.org/2000/svg' viewBox='0 0 16 16'><rect width='16' height='16' rx='4' fill='%230d6e8c'/><circle cx='8' cy='8' r='3' fill='%23e9f3f3'/></svg>">
+<!-- The icon is the wordmark's own b on an accent tile, as the design draws
+     it at app-icon size. Its outline is the same string as #mark-b below —
+     one letter, two places; tests/test_header_logo.py keeps them equal. -->
+<link rel="icon" href="data:image/svg+xml,<svg xmlns='http://www.w3.org/2000/svg' viewBox='0 0 16 16' fill-rule='evenodd'><rect width='16' height='16' rx='4' fill='%230d6e8c'/><path fill='%23ffffff' transform='translate(4.81 3.57) scale(.011)' d='M15 0H178V210H330C450 210 565 305 565 420V530C565 645 450 740 330 740H15V648H60V92H15ZM178 314V636H305C385 636 447 585 447 530V420C447 365 385 314 305 314Z'/></svg>">
 <link rel="preconnect" href="https://fonts.googleapis.com">
 <link rel="preconnect" href="https://fonts.gstatic.com" crossorigin>
 <link rel="stylesheet" href="https://fonts.googleapis.com/css2?family=IBM+Plex+Mono:wght@400;500&family=IBM+Plex+Sans:ital,wght@0,400;0,500;0,600;1,400&display=swap">
@@ -23,6 +26,8 @@
     --on-accent:#0a161b; --on-calm:#141a10;
     --shadow:0 10px 24px -18px rgba(0,0,0,.9);
     --pad:14px; --gap:10px; --radius:10px; --col:296px; --col-min:240px;
+    /* the wordmark's b-height — the one number that sizes the logo */
+    --logo-h:14px;
     --sans:'IBM Plex Sans',system-ui,sans-serif;
     --mono:'IBM Plex Mono',ui-monospace,SFMono-Regular,Menlo,monospace;
   }
@@ -74,8 +79,13 @@
     display:flex;align-items:center;gap:14px;padding:10px 18px;flex-wrap:wrap;
     background:var(--canvas);border-bottom:1px solid var(--border);
   }
-  .brand{display:flex;align-items:baseline;gap:10px}
-  .brand b{font-size:15px;font-weight:600;letter-spacing:-.01em}
+  /* The word is the logo — "bench" set in Zilla Slab SemiBold, tracked
+     -.015em. It ships as outlines, not text: this page may not fetch a font
+     for it, and outlines can never fall back to something else. currentColor
+     gives it the theme's own ink, so it is never a colour that means state,
+     and --logo-h scales it in one place rather than per theme.           */
+  .brand{display:flex;align-items:baseline;gap:11px}
+  .brand .mark{height:var(--logo-h);width:auto;fill:currentColor;flex:none}
   .brand .path{font-family:var(--mono);font-size:11.5px;color:var(--dim)}
   .views{display:flex;gap:2px;padding:3px;background:var(--sunken);border:1px solid var(--border-soft);border-radius:8px}
   .views button{padding:5px 12px;border:1px solid transparent;border-radius:6px;font-size:12.5px;font-weight:500;color:var(--muted)}
@@ -476,7 +486,20 @@
 </head>
 <body>
 <header>
-  <div class="brand"><b>Bench</b><span class="path" id="root"></span></div>
+  <!-- The wordmark, one glyph per path, on a 1000-unit em: baseline at y=740,
+       x-height top at 210, ascender at 0; the box runs to 746 to hold the
+       round letters' overshoot. Translations are the advance widths with the
+       design's -.015em tracking already folded in. -->
+  <div class="brand">
+    <svg class="mark" viewBox="0 0 2674 746" fill-rule="evenodd" role="img" aria-label="bench">
+      <path id="mark-b" d="M15 0H178V210H330C450 210 565 305 565 420V530C565 645 450 740 330 740H15V648H60V92H15ZM178 314V636H305C385 636 447 585 447 530V420C447 365 385 314 305 314Z"/>
+      <path transform="translate(565)" d="M205 204H319C415 204 494 283 494 379V522H148V582C148 616 172 642 206 642H330C395 642 445 615 470 566V670C440 712 390 746 319 746H205C109 746 30 667 30 571V379C30 283 109 204 205 204ZM148 428V368C148 335 172 308 206 308H318C352 308 376 335 376 368V428Z"/>
+      <path transform="translate(1074)" d="M15 210H330C450 210 520 300 520 400V648H565V740H357V648H402V400C402 345 375 314 320 314H178V648H223V740H15V648H60V302H15Z"/>
+      <path transform="translate(1639)" d="M300 204C358 204 404 212 438 236L392 326C365 313 336 308 300 308C212 308 148 378 148 475C148 572 212 642 300 642C336 642 365 637 392 624L438 714C404 738 358 746 300 746C167 746 30 640 30 475C30 310 167 204 300 204Z"/>
+      <path transform="translate(2094)" d="M15 0H178V210H330C450 210 520 300 520 400V648H565V740H357V648H402V400C402 345 375 314 320 314H178V648H223V740H15V648H60V92H15Z"/>
+    </svg>
+    <span class="path" id="root"></span>
+  </div>
   <nav class="views" id="views">
     <button data-view="board" class="on">Board</button>
     <button data-view="flight">Sessions</button>
diff --git a/tests/test_header_logo.py b/tests/test_header_logo.py
new file mode 100644
index 0000000..c69e688
--- /dev/null
+++ b/tests/test_header_logo.py
@@ -0,0 +1,169 @@
+"""The header wears the design's wordmark (task 23).
+
+The design's answer to "what is the bench logo" is that there isn't a drawn
+one: the word *is* the logo — "bench", lowercase, set in Zilla Slab SemiBold
+and tracked -.015em, with the b lifted out of the same face as the icon. The
+board cannot fetch that face (the page adds no network requests for a logo),
+so the mark ships as outlines instead, and the b's outline is reused verbatim
+as the tab icon.
+
+board.html has no frontend test runner, so this is checked the way task 22's
+browser half is: as source-level invariants — the ones that, if broken, would
+put the mark back on a font, bake a colour into it, let the two copies of the
+b drift apart, or shove the header's neighbours around.
+
+    python3 -m unittest discover -s tests -v
+"""
+
+from __future__ import annotations
+
+import re
+import unittest
+from pathlib import Path
+
+REPO = Path(__file__).resolve().parents[1]
+BOARD = REPO / "manager" / "core" / "board.html"
+
+# What the page was already allowed to fetch before the logo landed. The list
+# is the point: a logo that needed a font would have to grow it.
+KNOWN_EXTERNALS = {
+    "https://fonts.googleapis.com",
+    "https://fonts.gstatic.com",
+    "https://fonts.googleapis.com/css2?family=IBM+Plex+Mono:wght@400;500"
+    "&family=IBM+Plex+Sans:ital,wght@0,400;0,500;0,600;1,400&display=swap",
+}
+
+# Colour only ever means state, so none of these may appear in the mark.
+STATE_TOKENS = ("var(--accent)", "var(--calm)", "var(--alarm)", "var(--idle)")
+
+
+class Fixture(unittest.TestCase):
+    @classmethod
+    def setUpClass(cls):
+        cls.html = BOARD.read_text(encoding="utf-8")
+
+    def mark(self) -> str:
+        """The inline wordmark, markup and all."""
+        found = re.search(r'<svg class="mark".*?</svg>', self.html, re.DOTALL)
+        self.assertIsNotNone(found, "board.html lost the inline wordmark")
+        return found.group(0)
+
+    def icon_href(self) -> str:
+        found = re.search(r'<link rel="icon" href="([^"]*)"', self.html)
+        self.assertIsNotNone(found, "board.html lost its tab icon")
+        return found.group(1)
+
+
+class TheWordmark(Fixture):
+    def test_the_header_carries_it_as_outlines(self):
+        """Outlines, not text: a font-set wordmark on this page would either
+        need a fetch or silently fall back to whatever the OS has."""
+        brand = re.search(r'<div class="brand">.*?</div>', self.html, re.DOTALL)
+        self.assertIsNotNone(brand, "board.html lost the .brand block")
+        self.assertIn('<svg class="mark"', brand.group(0))
+        self.assertNotIn("<b>Bench</b>", self.html,
+                         "the old font-set wordmark is still in the header")
+
+    def test_the_word_is_the_lowercase_one(self):
+        """"bench", not "Bench" — the design sets it lowercase everywhere, and
+        the accessible name is the only place the word survives as text."""
+        self.assertIn('aria-label="bench"', self.mark())
+
+    def test_it_spells_five_letters(self):
+        """One path per letter of b-e-n-c-h. A missing path is a missing
+        letter, and nothing else in this file would notice."""
+        self.assertEqual(len(re.findall(r"<path\b", self.mark())), 5)
+
+    def test_nothing_is_fetched_for_it(self):
+        """The whole reason it is outlines. If this fails, the page grew a
+        request (or an @font-face) that the acceptance forbids."""
+        externals = set(re.findall(r'(?:href|src)="(https?://[^"]+)"', self.html))
+        self.assertEqual(externals, KNOWN_EXTERNALS,
+                         "board.html gained an external resource")
+        for forbidden in ("@font-face", ".woff", ".ttf", "family=Zilla"):
+            self.assertNotIn(forbidden, self.html,
+                             f"the logo may not bring in {forbidden}")
+        # Naming the source face in a comment is documentation; setting text
+        # in it would be a font the page hasn't got.
+        self.assertIsNone(re.search(r"font-family:[^;}\n]*Zilla", self.html),
+                          "the mark is outlines — nothing is set in Zilla Slab")
+
+    def test_it_takes_the_theme_s_own_ink(self):
+        """currentColor is the theme mechanism: Night and Daylight both get
+        --text without a second copy of the mark."""
+        rule = re.search(r"\.brand \.mark\{([^}]*)\}", self.html)
+        self.assertIsNotNone(rule, "board.html lost the .brand .mark rule")
+        self.assertIn("fill:currentColor", rule.group(1))
+        self.assertNotRegex(self.mark(), r"#[0-9a-fA-F]{3,6}\b",
+                            "the mark must not bake a colour in")
+
+    def test_it_is_not_coloured_like_a_state(self):
+        """--accent means an agent is alive. A logo wearing it would be
+        lying about the board twice a second."""
+        for token in STATE_TOKENS:
+            self.assertNotIn(token, self.mark())
+
+    def test_one_token_sizes_it(self):
+        """Scaling is a custom property, per the design — not two hard-coded
+        sizes to keep in step."""
+        self.assertRegex(self.html, r":root\{[^}]*--logo-h:", )
+        rule = re.search(r"\.brand \.mark\{([^}]*)\}", self.html)
+        self.assertIn("height:var(--logo-h)", rule.group(1))
+
+
+class TheTabIcon(Fixture):
+    def test_it_never_leaves_the_page(self):
+        """Inline data: URI, so the tab is right on first paint and offline."""
+        self.assertTrue(self.icon_href().startswith("data:image/svg+xml,"),
+                        "the tab icon must stay inline")
+
+    def test_it_is_the_wordmark_s_own_b(self):
+        """The design's point about this mark is that one face does both jobs,
+        so they can never drift apart. Here that means one outline: the icon's
+        path and the wordmark's b are the same string, character for
+        character."""
+        icon = re.search(r"d='([^']+)'", self.icon_href())
+        self.assertIsNotNone(icon, "the tab icon lost its b")
+        word = re.search(r'<path id="mark-b" d="([^"]+)"', self.html)
+        self.assertIsNotNone(word, "the wordmark lost its b")
+        self.assertEqual(icon.group(1), word.group(1),
+                         "the icon's b and the wordmark's b have drifted apart")
+
+    def test_the_holes_in_the_b_are_holes(self):
+        """The b's bowl is a counter, drawn as a second subpath. Without
+        even-odd filling it fills solid and the letter becomes a blob."""
+        self.assertIn("fill-rule='evenodd'", self.icon_href())
+        self.assertIn('fill-rule="evenodd"', self.mark())
+
+
+class TheNeighbours(Fixture):
+    """The card is the logo only: everything beside it stays put."""
+
+    def test_the_path_line_still_hangs_off_the_baseline(self):
+        """Baseline alignment against the tasks-root path is the design's own
+        arrangement, and it is what keeps the mono line optically seated."""
+        rule = re.search(r"\.brand\{([^}]*)\}", self.html)
+        self.assertIsNotNone(rule, "board.html lost the .brand rule")
+        self.assertIn("align-items:baseline", rule.group(1))
+
+    def test_the_path_line_is_untouched(self):
+        self.assertIn(".brand .path{font-family:var(--mono);font-size:11.5px;"
+                      "color:var(--dim)}", self.html)
+
+    def test_the_header_row_is_untouched(self):
+        """Same padding, same alignment, same order — the mark replaced a
+        word, it did not relayout the header."""
+        rule = re.search(r"\n  header\{([^}]*)\}", self.html)
+        self.assertIsNotNone(rule, "board.html lost the header rule")
+        self.assertIn("align-items:center", rule.group(1))
+        self.assertIn("padding:10px 18px", rule.group(1))
+        header = re.search(r"<header>.*?</header>", self.html, re.DOTALL)
+        self.assertIsNotNone(header, "board.html lost its header")
+        order = re.findall(r'id="(views|syncchip|livechip|themebtn|refresh)"',
+                           header.group(0))
+        self.assertEqual(order, ["views", "syncchip", "livechip",
+                                 "themebtn", "refresh"])
+
+
+if __name__ == "__main__":
+    unittest.main()
