diff --git a/docs/webui-local-dev.md b/docs/webui-local-dev.md
index 33dbf61..06ad035 100644
--- a/docs/webui-local-dev.md
+++ b/docs/webui-local-dev.md
@@ -54,6 +54,7 @@ status, onboarding checklist state, and the fail-closed error payloads (#635).
 | `/` | Home / operator overview |
 | `/health` | JSON liveness (`status`, `service`, `mode`, `timestamp`, `uptime_seconds`) |
 | `/api/v1/system/health` | Structured read-only system health (#634) |
+| `/system-health` | System-health dashboard — readiness, version/uptime, dependencies, MCP namespaces, stale-runtime parity (#639) |
 | `/queue` | Live PR and issue queue dashboard (#429) |
 | `/api/queue` | JSON queue export with pagination metadata |
 | `/projects` | Project registry list with status and onboarding progress (#427, #635) |
@@ -233,6 +234,37 @@ health, workflow/schema SHA-256 hashes, and stale-runtime warnings when the
 checkout is behind merged safety-gate changes. Restart guidance links to #420;
 no tokens or MCP restart actions are exposed.
 
+## System-health dashboard (#639)
+
+`/system-health` renders the same snapshot the `/api/v1/system/health` API
+returns, so the page and the API can never disagree. Cards: overall readiness,
+stale-runtime parity, version and uptime, dependency probes, MCP namespaces,
+probe errors (only when present), and recovery pointers. `?deep=1` opts into
+the network probe exactly as the API does; the plain page load stays cheap.
+
+Field authority and honesty rules:
+
+* `ready` and `readiness_complete` are shown separately. A snapshot whose
+  required probes never ran is not the same as one that ran them and passed,
+  and the page never collapses the two into an unproven green.
+* A probe that did not run appears under **Not probed**, never as healthy.
+* `stale_runtime.mutation_safe` is displayed verbatim from the API. When the
+  runtime is stale, or when parity is indeterminate, the page warns and does
+  not claim mutation safety.
+* MCP namespaces are reported `unproven`: the web process runs outside the
+  IDE-managed MCP client and cannot prove that path (#543).
+
+Redaction is split by field kind. Free text — probe details, readiness and
+parity reasons, probe errors — passes through `system_health.redact`.
+Structured fields — commit SHAs, probe names, statuses, timestamps — are
+HTML-escaped only, because `redact`'s opaque-token rule matches any run of 32
+or more characters and would otherwise blank every 40-character git SHA, which
+is precisely the evidence the parity view exists to show.
+
+The dashboard is read-only: no restart, reload, or process-kill control. Those
+arrive in Phase 2 (#642). Recovery guidance points at the sanctioned client
+reconnect / operator restart path — never a manual daemon kill (#630).
+
 ## Deployment boundary (#435)
 
 MVP serves on loopback by default. Binding `0.0.0.0` or `::` is **refused**
diff --git a/tests/test_webui_system_health_dashboard.py b/tests/test_webui_system_health_dashboard.py
new file mode 100644
index 0000000..cd52cd8
--- /dev/null
+++ b/tests/test_webui_system_health_dashboard.py
@@ -0,0 +1,341 @@
+"""Tests for the system-health dashboard view (#639).
+
+Covers the acceptance criteria directly: the page renders the health DTO
+fields (AC1), degraded dependencies are visible (AC2), stale runtime is warned
+prominently and never rendered as mutation-safe (AC3), healthy and degraded
+fixtures both render (AC4), and the shell carries a nav entry (AC5).
+"""
+import sys
+import unittest
+from pathlib import Path
+
+sys.path.insert(0, str(Path(__file__).resolve().parent.parent))
+
+from starlette.testclient import TestClient
+
+from webui.app import create_app
+from webui.deployment_boundary import scan_text_for_client_secrets
+from webui.layout import NAV_ITEMS, render_page
+from webui.system_health import (
+    STATUS_DEGRADED,
+    STATUS_DOWN,
+    STATUS_OK,
+    STATUS_SKIPPED,
+    STATUS_UNPROVEN,
+    DependencyProbe,
+    StaleRuntime,
+    SystemHealthSnapshot,
+    VersionInfo,
+)
+from webui.system_health_views import render_system_health_page
+
+DASHBOARD_PATH = "/system-health"
+
+
+def _version(*, known: bool = True) -> VersionInfo:
+    return VersionInfo(
+        git_sha="1c455b6ec0f9cb761fe6248de68c17e061fb5ecd" if known else None,
+        git_describe="v0.4.1-12-g1c455b6" if known else None,
+        control_plane_schema_version=4 if known else None,
+        python_version="3.13.1",
+        known=known,
+    )
+
+
+def _parity(*, stale: bool = False, determinable: bool = True) -> StaleRuntime:
+    if stale:
+        return StaleRuntime(
+            daemon_head="aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa",
+            checkout_head="bbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbb",
+            remote_head="cccccccccccccccccccccccccccccccccccccccc",
+            stale=True,
+            determinable=True,
+            mutation_safe=False,
+            reasons=("runtime, checkout, and remote commits disagree",),
+        )
+    if not determinable:
+        return StaleRuntime(
+            daemon_head=None,
+            checkout_head=None,
+            remote_head=None,
+            stale=False,
+            determinable=False,
+            mutation_safe=False,
+            reasons=("local checkout HEAD could not be read",),
+        )
+    return StaleRuntime(
+        daemon_head="1c455b6ec0f9cb761fe6248de68c17e061fb5ecd",
+        checkout_head="1c455b6ec0f9cb761fe6248de68c17e061fb5ecd",
+        remote_head="1c455b6ec0f9cb761fe6248de68c17e061fb5ecd",
+        stale=False,
+        determinable=True,
+        mutation_safe=True,
+        reasons=(),
+    )
+
+
+def _snapshot(
+    *,
+    status: str = STATUS_OK,
+    ready: bool = True,
+    readiness_complete: bool = True,
+    readiness_reasons: tuple[str, ...] = (),
+    dependencies: tuple[DependencyProbe, ...] | None = None,
+    parity: StaleRuntime | None = None,
+    namespaces: tuple[dict, ...] = (),
+    probe_errors: tuple[str, ...] = (),
+    version_known: bool = True,
+) -> SystemHealthSnapshot:
+    if dependencies is None:
+        dependencies = (
+            DependencyProbe(
+                name="control_plane_db",
+                kind="sqlite",
+                status=STATUS_OK,
+                detail="schema version 4",
+                required=True,
+                latency_ms=1.25,
+                metadata={"schema_version": 4},
+            ),
+        )
+    return SystemHealthSnapshot(
+        status=status,
+        ready=ready,
+        readiness_complete=readiness_complete,
+        readiness_reasons=readiness_reasons,
+        service="mcp-control-plane-webui",
+        mode="read-only",
+        version=_version(known=version_known),
+        started_at="2026-07-23T19:50:47+00:00",
+        uptime_seconds=3661.5,
+        timestamp="2026-07-23T20:51:48+00:00",
+        deep_probes_requested=False,
+        dependencies=dependencies,
+        mcp_namespaces=namespaces,
+        stale_runtime=parity if parity is not None else _parity(),
+        probe_errors=probe_errors,
+    )
+
+
+class TestHealthyRender(unittest.TestCase):
+    """AC1 / AC4 — every health DTO field reaches the page."""
+
+    def setUp(self):
+        self.html = render_system_health_page(_snapshot())
+
+    def test_readiness_fields_render(self):
+        self.assertIn("System health", self.html)
+        self.assertIn("Ready", self.html)
+        self.assertIn("mcp-control-plane-webui", self.html)
+        self.assertIn("read-only", self.html)
+        self.assertIn("2026-07-23T20:51:48+00:00", self.html)
+
+    def test_version_and_uptime_render(self):
+        self.assertIn("1c455b6ec0f9cb761fe6248de68c17e061fb5ecd", self.html)
+        self.assertIn("v0.4.1-12-g1c455b6", self.html)
+        self.assertIn("3.13.1", self.html)
+        self.assertIn("3661.500s", self.html)
+        self.assertIn("1.02h", self.html)
+
+    def test_dependency_row_renders_with_latency(self):
+        self.assertIn("control_plane_db", self.html)
+        self.assertIn("sqlite", self.html)
+        self.assertIn("schema version 4", self.html)
+        self.assertIn("1.2 ms", self.html)
+
+    def test_healthy_page_shows_no_stale_warning(self):
+        self.assertNotIn("Stale runtime:", self.html)
+        self.assertNotIn("Staleness", self.html)
+
+    def test_unknown_version_is_labelled_not_faked(self):
+        html = render_system_health_page(_snapshot(version_known=False))
+        self.assertIn("unknown", html)
+        self.assertIn("unresolved", html)
+
+
+class TestDegradedRender(unittest.TestCase):
+    """AC2 — a degraded or unrun dependency is visible, not swallowed."""
+
+    def setUp(self):
+        self.deps = (
+            DependencyProbe(
+                name="control_plane_db",
+                kind="sqlite",
+                status=STATUS_OK,
+                detail="schema version 4",
+                required=True,
+                latency_ms=0.9,
+            ),
+            DependencyProbe(
+                name="repository",
+                kind="git",
+                status=STATUS_DOWN,
+                detail="repository root is not a git checkout",
+                required=True,
+                latency_ms=4.0,
+            ),
+            DependencyProbe(
+                name="gitea",
+                kind="http",
+                status=STATUS_SKIPPED,
+                detail="deep probe not requested",
+                required=False,
+            ),
+        )
+        self.html = render_system_health_page(
+            _snapshot(
+                status=STATUS_DEGRADED,
+                ready=False,
+                readiness_complete=False,
+                readiness_reasons=("required dependency 'repository' is down",),
+                dependencies=self.deps,
+            )
+        )
+
+    def test_degraded_banner_names_the_dependency(self):
+        self.assertIn("Degraded dependencies:", self.html)
+        self.assertIn("repository", self.html)
+
+    def test_not_run_probe_is_reported_separately(self):
+        self.assertIn("Not probed:", self.html)
+        self.assertIn("gitea", self.html)
+        self.assertIn("not counted", self.html)
+
+    def test_not_ready_headline_and_reason(self):
+        self.assertIn("Not ready", self.html)
+        self.assertIn("required dependency 'repository' is down", self.html)
+
+    def test_degraded_status_badge_present(self):
+        self.assertIn("badge-health-degraded", self.html)
+        self.assertIn("badge-health-down", self.html)
+
+    def test_ready_but_incomplete_is_not_shown_as_plain_ready(self):
+        html = render_system_health_page(
+            _snapshot(ready=True, readiness_complete=False)
+        )
+        self.assertIn("Ready (incomplete evidence)", html)
+
+
+class TestStaleRuntimeWarning(unittest.TestCase):
+    """AC3 — staleness is prominent and never claims mutation safety."""
+
+    def test_stale_runtime_warns_and_denies_mutation_safety(self):
+        html = render_system_health_page(_snapshot(parity=_parity(stale=True)))
+        self.assertIn("Stale runtime:", html)
+        self.assertIn("do not treat this runtime as mutation-safe", html)
+        self.assertIn("<tr><th>Mutation safe</th><td>False</td></tr>", html)
+
+    def test_indeterminate_parity_is_not_reported_safe(self):
+        html = render_system_health_page(
+            _snapshot(parity=_parity(determinable=False))
+        )
+        self.assertIn("Staleness", html)
+        self.assertIn("<tr><th>Mutation safe</th><td>False</td></tr>", html)
+        self.assertIn("<tr><th>Determinable</th><td>False</td></tr>", html)
+
+    def test_healthy_parity_reports_mutation_safe_true(self):
+        html = render_system_health_page(_snapshot())
+        self.assertIn("<tr><th>Mutation safe</th><td>True</td></tr>", html)
+
+
+class TestNamespacesAndErrors(unittest.TestCase):
+    def test_unproven_namespace_rows_render(self):
+        html = render_system_health_page(
+            _snapshot(
+                namespaces=(
+                    {
+                        "namespace": "gitea-author",
+                        "required_tool": "gitea_lock_issue",
+                        "status": STATUS_UNPROVEN,
+                        "ide_namespace_proven": False,
+                        "reason": "the web console cannot invoke the IDE-managed MCP client",
+                    },
+                )
+            )
+        )
+        self.assertIn("gitea-author", html)
+        self.assertIn("gitea_lock_issue", html)
+        self.assertIn("badge-health-unproven", html)
+
+    def test_no_namespaces_degrades_gracefully(self):
+        html = render_system_health_page(_snapshot(namespaces=()))
+        self.assertIn("No MCP namespaces are declared.", html)
+
+    def test_probe_errors_render_when_present(self):
+        html = render_system_health_page(
+            _snapshot(probe_errors=("probe raised: disk offline",))
+        )
+        self.assertIn("Probe errors", html)
+        self.assertIn("disk offline", html)
+
+    def test_probe_error_card_absent_when_clean(self):
+        self.assertNotIn("Probe errors", render_system_health_page(_snapshot()))
+
+
+class TestReadOnlyAndRedaction(unittest.TestCase):
+    def test_no_restart_or_kill_controls(self):
+        html = render_system_health_page(_snapshot())
+        self.assertNotIn("<button", html)
+        self.assertNotIn("<form", html)
+        self.assertNotIn("pkill", html)
+        self.assertIn("read-only", html)
+
+    def test_recovery_points_at_sanctioned_path(self):
+        html = render_system_health_page(_snapshot())
+        self.assertIn("Reconnect the MCP client", html)
+        self.assertIn("Never kill the daemon process manually", html)
+
+    def test_secret_shaped_detail_is_redacted(self):
+        leaky = DependencyProbe(
+            name="gitea",
+            kind="http",
+            status=STATUS_DOWN,
+            detail="auth failed for token=ghp_ABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789",
+            required=False,
+            latency_ms=12.0,
+        )
+        html = render_system_health_page(_snapshot(dependencies=(leaky,)))
+        self.assertNotIn("ghp_ABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789", html)
+
+    def test_html_in_detail_is_escaped(self):
+        hostile = DependencyProbe(
+            name="repository",
+            kind="git",
+            status=STATUS_DOWN,
+            detail="<script>alert(1)</script>",
+            required=True,
+        )
+        html = render_system_health_page(_snapshot(dependencies=(hostile,)))
+        self.assertNotIn("<script>", html)
+        self.assertIn("&lt;script&gt;", html)
+
+
+class TestNavAndRoute(unittest.TestCase):
+    """AC5 — the shell links the dashboard, and the route serves it."""
+
+    def setUp(self):
+        self.client = TestClient(create_app())
+
+    def test_nav_contains_system_health(self):
+        self.assertIn((DASHBOARD_PATH, "System health"), NAV_ITEMS)
+
+    def test_rendered_shell_links_dashboard(self):
+        page = render_page(title="Home", body_html="<p>x</p>")
+        self.assertIn(f'href="{DASHBOARD_PATH}"', page)
+
+    def test_route_renders_dashboard(self):
+        response = self.client.get(DASHBOARD_PATH)
+        self.assertEqual(response.status_code, 200)
+        self.assertIn("System health", response.text)
+        self.assertIn("Stale-runtime parity", response.text)
+
+    def test_route_is_read_only(self):
+        self.assertEqual(self.client.post(DASHBOARD_PATH).status_code, 405)
+
+    def test_live_page_leaks_no_client_secret(self):
+        findings = scan_text_for_client_secrets(self.client.get(DASHBOARD_PATH).text)
+        self.assertEqual(findings, [])
+
+
+if __name__ == "__main__":  # pragma: no cover
+    unittest.main()
diff --git a/webui/app.py b/webui/app.py
index 2a79d6c..9a2b801 100644
--- a/webui/app.py
+++ b/webui/app.py
@@ -51,6 +51,7 @@ from webui.system_health import (
     process_uptime,
     snapshot_to_dict as system_health_to_dict,
 )
+from webui.system_health_views import render_system_health_page
 
 _READ_ONLY_METHODS = frozenset({"GET", "HEAD", "OPTIONS"})
 _AUDIT_MUTATION_PATHS = frozenset({"/audit", "/api/audit"})
@@ -121,6 +122,24 @@ async def api_system_health(request: Request) -> JSONResponse:
     return JSONResponse(payload, status_code=200 if snapshot.ready else 503)
 
 
+async def system_health(request: Request) -> HTMLResponse:
+    """Read-only system-health dashboard (#639).
+
+    Shares the #634 snapshot loader with the JSON API so the page can never
+    disagree with it. `?deep=1` opts into the network probe exactly as the API
+    does; the default page load stays cheap. The response is always 200: this
+    is an operator view that must render the degraded state, not withhold it.
+    """
+    deep = _truthy_flag(request.query_params.get("deep"))
+    snapshot = load_system_health(deep=deep)
+    return HTMLResponse(
+        render_page(
+            title="System health",
+            body_html=render_system_health_page(snapshot),
+        )
+    )
+
+
 async def queue(_request: Request) -> HTMLResponse:
     snapshot = load_queue_snapshot()
     return HTMLResponse(render_page(title="Queue", body_html=render_queue_page(snapshot)))
@@ -433,6 +452,7 @@ def create_app(*, bind_host: str | None = None) -> Starlette:
             Route("/", home, methods=["GET"]),
             Route("/health", health, methods=["GET"]),
             Route(SYSTEM_HEALTH_API_PATH, api_system_health, methods=["GET"]),
+            Route("/system-health", system_health, methods=["GET"]),
             Route("/queue", queue, methods=["GET"]),
             Route("/api/queue", api_queue, methods=["GET"]),
             Route("/projects", projects, methods=["GET"]),
diff --git a/webui/layout.py b/webui/layout.py
index 47bedc1..82e92ff 100644
--- a/webui/layout.py
+++ b/webui/layout.py
@@ -4,6 +4,7 @@ from __future__ import annotations
 
 NAV_ITEMS = (
     ("/", "Home"),
+    ("/system-health", "System health"),
     ("/queue", "Queue"),
     ("/projects", "Projects"),
     ("/prompts", "Prompts"),
@@ -161,6 +162,25 @@ def render_page(*, title: str, body_html: str, extra_head: str = "") -> str:
     .badge-in-review {{ color: #9ec8f0; border-color: #3d5f7a; }}
     .badge-duplicate {{ color: #e0c27a; border-color: #6b5730; }}
     .badge-stale {{ color: #c9b8e8; border-color: #5a4a78; }}
+    .badge-health-ok {{ color: #8fd19e; border-color: #3d6b4a; }}
+    .badge-health-degraded {{ color: #e0c27a; border-color: #6b5730; }}
+    .badge-health-down {{ color: #f0a8a8; border-color: #7a3b3b; }}
+    .badge-health-skipped {{ color: var(--muted); }}
+    .badge-health-unproven {{ color: #c9b8e8; border-color: #5a4a78; }}
+    .health-card {{
+      margin: 1.25rem 0;
+      padding: 0.85rem 1rem 1rem;
+      border: 1px solid var(--border);
+      border-radius: 8px;
+      background: var(--surface);
+    }}
+    .health-card h3 {{ margin: 0 0 0.5rem; font-size: 1.05rem; }}
+    .health-card h4 {{ margin: 1rem 0 0.35rem; font-size: 0.92rem; color: var(--muted); }}
+    .health-headline {{ color: var(--text); font-size: 1rem; margin: 0 0 0.5rem; }}
+    .health-degraded {{ border-left-color: #e0c27a; }}
+    .health-stale {{ border-left-color: #f0a8a8; }}
+    ul.reasons {{ margin: 0.35rem 0; padding-left: 1.15rem; color: var(--muted); font-size: 0.9rem; }}
+    ul.reasons li {{ margin-bottom: 0.3rem; }}
   </style>
   {extra_head}
 </head>
diff --git a/webui/system_health_views.py b/webui/system_health_views.py
new file mode 100644
index 0000000..e7ba492
--- /dev/null
+++ b/webui/system_health_views.py
@@ -0,0 +1,307 @@
+"""HTML views for the system-health dashboard (#639).
+
+Renders the read-only :class:`~webui.system_health.SystemHealthSnapshot`
+produced by the Phase 1 system-health API (#634). The page offers no restart,
+reload, or process-kill control: those are Phase 2 work, and manual process
+kills are the contamination path #630 exists to prevent.
+
+Every free-text field passes through :func:`webui.system_health.redact` before
+it reaches HTML, so a probe detail that captured a token or a credentialed URL
+cannot leak through the dashboard even though the API redacts it already.
+"""
+
+from __future__ import annotations
+
+import html
+
+from webui.system_health import (
+    STATUS_DEGRADED,
+    STATUS_DOWN,
+    STATUS_OK,
+    STATUS_SKIPPED,
+    STATUS_UNPROVEN,
+    DependencyProbe,
+    SystemHealthSnapshot,
+    redact,
+)
+
+_STATUS_BADGE_CLASS = {
+    STATUS_OK: "badge-health-ok",
+    STATUS_DEGRADED: "badge-health-degraded",
+    STATUS_DOWN: "badge-health-down",
+    STATUS_SKIPPED: "badge-health-skipped",
+    STATUS_UNPROVEN: "badge-health-unproven",
+}
+
+
+def _safe(value: object) -> str:
+    """Escape free text for HTML after redacting anything secret-shaped.
+
+    Use this for every value that can carry arbitrary text — probe details,
+    reasons, probe errors — because those are where a credential could ride
+    along.
+    """
+    return html.escape(redact(str(value)))
+
+
+def _esc(value: object) -> str:
+    """Escape a structured field for HTML without redacting it.
+
+    Commit SHAs, probe names, statuses, and timestamps are enumerated or
+    machine-generated, never credential-bearing. They must not go through
+    :func:`redact`: its opaque-token rule matches any 32-plus-character run,
+    so a 40-character git SHA would render as ``[redacted]`` and the parity
+    view — the one thing an operator reads this page for — would be blank.
+    """
+    return html.escape(str(value))
+
+
+def _status_badge(status: str) -> str:
+    css = _STATUS_BADGE_CLASS.get(status, "badge-health-unproven")
+    return f'<span class="badge {css}">{_esc(status)}</span>'
+
+
+def _reason_list(reasons: tuple[str, ...], *, empty: str) -> str:
+    if not reasons:
+        return f"<p class='muted'>{html.escape(empty)}</p>"
+    items = "".join(f"<li>{_safe(reason)}</li>" for reason in reasons)
+    return f"<ul class='reasons'>{items}</ul>"
+
+
+def _readiness_card(snapshot: SystemHealthSnapshot) -> str:
+    """Overall readiness.
+
+    ``ready`` and ``readiness_complete`` are shown separately on purpose: a
+    snapshot whose required probes never ran is not the same as one that ran
+    them and passed, and collapsing the two would render an unproven green.
+    """
+    if snapshot.ready and snapshot.readiness_complete:
+        headline = "Ready"
+    elif snapshot.ready:
+        headline = "Ready (incomplete evidence)"
+    else:
+        headline = "Not ready"
+
+    return (
+        "<section class='health-card'>"
+        f"<h3>Readiness {_status_badge(snapshot.status)}</h3>"
+        f"<p class='health-headline'>{html.escape(headline)}</p>"
+        "<table class='detail'>"
+        f"<tr><th>Service</th><td><code>{_esc(snapshot.service)}</code></td></tr>"
+        f"<tr><th>Mode</th><td>{_esc(snapshot.mode)}</td></tr>"
+        f"<tr><th>Ready</th><td>{_esc(snapshot.ready)}</td></tr>"
+        "<tr><th>Readiness evidence complete</th>"
+        f"<td>{_esc(snapshot.readiness_complete)}</td></tr>"
+        "<tr><th>Deep probes requested</th>"
+        f"<td>{_esc(snapshot.deep_probes_requested)}</td></tr>"
+        f"<tr><th>Observed at</th><td><code>{_esc(snapshot.timestamp)}</code></td></tr>"
+        "</table>"
+        "<h4>Readiness reasons</h4>"
+        f"{_reason_list(snapshot.readiness_reasons, empty='No readiness objections recorded.')}"
+        "</section>"
+    )
+
+
+def _version_card(snapshot: SystemHealthSnapshot) -> str:
+    version = snapshot.version
+    uptime_hours = snapshot.uptime_seconds / 3600.0
+    known = (
+        "resolved"
+        if version.known
+        else "unresolved — version fields could not be read from the checkout"
+    )
+    schema = version.control_plane_schema_version
+    return (
+        "<section class='health-card'>"
+        "<h3>Version and uptime</h3>"
+        "<table class='detail'>"
+        f"<tr><th>Git SHA</th><td><code>{_esc(version.git_sha or 'unknown')}</code></td></tr>"
+        "<tr><th>Git describe</th>"
+        f"<td><code>{_esc(version.git_describe or 'unknown')}</code></td></tr>"
+        "<tr><th>Control-plane schema</th>"
+        f"<td>{_esc(schema if schema is not None else 'unknown')}</td></tr>"
+        f"<tr><th>Python</th><td><code>{_esc(version.python_version)}</code></td></tr>"
+        f"<tr><th>Version status</th><td>{html.escape(known)}</td></tr>"
+        f"<tr><th>Started at</th><td><code>{_esc(snapshot.started_at)}</code></td></tr>"
+        "<tr><th>Uptime</th>"
+        f"<td>{snapshot.uptime_seconds:.3f}s ({uptime_hours:.2f}h)</td></tr>"
+        "</table>"
+        "</section>"
+    )
+
+
+def _dependency_rows(probes: tuple[DependencyProbe, ...]) -> str:
+    if not probes:
+        return "<p class='muted'>No dependency probes were reported.</p>"
+    rows = []
+    for probe in probes:
+        latency = (
+            f"{probe.latency_ms:.1f} ms" if probe.latency_ms is not None else "n/a"
+        )
+        rows.append(
+            "<tr>"
+            f"<td><code>{_esc(probe.name)}</code></td>"
+            f"<td>{_esc(probe.kind)}</td>"
+            f"<td>{_status_badge(probe.status)}</td>"
+            f"<td>{_esc('required' if probe.required else 'optional')}</td>"
+            f"<td>{html.escape(latency)}</td>"
+            f"<td>{_safe(probe.detail)}</td>"
+            "</tr>"
+        )
+    return (
+        "<table class='registry'><thead><tr>"
+        "<th>Dependency</th><th>Kind</th><th>Status</th><th>Requirement</th>"
+        "<th>Latency</th><th>Detail</th>"
+        "</tr></thead><tbody>"
+        f"{''.join(rows)}</tbody></table>"
+    )
+
+
+def _dependency_card(snapshot: SystemHealthSnapshot) -> str:
+    degraded = [probe for probe in snapshot.dependencies if probe.ran and not probe.healthy]
+    not_run = [probe for probe in snapshot.dependencies if not probe.ran]
+
+    banner = ""
+    if degraded:
+        names = ", ".join(sorted(probe.name for probe in degraded))
+        banner += (
+            "<div class='stub health-degraded'><p><strong>Degraded dependencies:</strong> "
+            f"{_esc(names)}</p></div>"
+        )
+    if not_run:
+        names = ", ".join(sorted(probe.name for probe in not_run))
+        banner += (
+            "<div class='stub'><p><strong>Not probed:</strong> "
+            f"{_esc(names)} — these contribute no evidence and are not counted "
+            "as healthy.</p></div>"
+        )
+
+    return (
+        "<section class='health-card'>"
+        "<h3>Dependencies</h3>"
+        f"{banner}"
+        f"{_dependency_rows(snapshot.dependencies)}"
+        "<p class='muted'>Details are redacted at the API boundary and again "
+        "before rendering; credentials are never displayed.</p>"
+        "</section>"
+    )
+
+
+def _namespace_card(snapshot: SystemHealthSnapshot) -> str:
+    if not snapshot.mcp_namespaces:
+        body = "<p class='muted'>No MCP namespaces are declared.</p>"
+    else:
+        rows = []
+        for entry in snapshot.mcp_namespaces:
+            rows.append(
+                "<tr>"
+                f"<td><code>{_esc(entry.get('namespace'))}</code></td>"
+                f"<td><code>{_esc(entry.get('required_tool'))}</code></td>"
+                f"<td>{_status_badge(str(entry.get('status') or STATUS_UNPROVEN))}</td>"
+                f"<td>{_esc(entry.get('ide_namespace_proven'))}</td>"
+                f"<td>{_safe(entry.get('reason'))}</td>"
+                "</tr>"
+            )
+        body = (
+            "<table class='registry'><thead><tr>"
+            "<th>Namespace</th><th>Required tool</th><th>Status</th>"
+            "<th>IDE-proven</th><th>Reason</th>"
+            "</tr></thead><tbody>"
+            f"{''.join(rows)}</tbody></table>"
+        )
+    return (
+        "<section class='health-card'>"
+        "<h3>MCP namespaces</h3>"
+        f"{body}"
+        "<p class='muted'>The web process runs outside the IDE-managed MCP "
+        "client, so namespace health is reported as unproven rather than "
+        "guessed (#543).</p>"
+        "</section>"
+    )
+
+
+def _stale_runtime_card(snapshot: SystemHealthSnapshot) -> str:
+    stale = snapshot.stale_runtime
+    if stale.stale:
+        warning = (
+            "<div class='stub health-stale'><p><strong>Stale runtime:</strong> "
+            "the running code, the checkout, and the remote-tracking commit "
+            "disagree. Capability gates may be evaluating obsolete code — "
+            "do not treat this runtime as mutation-safe.</p></div>"
+        )
+    elif not stale.determinable:
+        warning = (
+            "<div class='stub health-stale'><p><strong>Staleness "
+            "indeterminate:</strong> parity could not be proven, so this "
+            "runtime is not reported as mutation-safe.</p></div>"
+        )
+    else:
+        warning = ""
+
+    return (
+        "<section class='health-card'>"
+        "<h3>Stale-runtime parity</h3>"
+        f"{warning}"
+        "<table class='detail'>"
+        "<tr><th>Daemon head</th>"
+        f"<td><code>{_esc(stale.daemon_head or 'unknown')}</code></td></tr>"
+        "<tr><th>Checkout head</th>"
+        f"<td><code>{_esc(stale.checkout_head or 'unknown')}</code></td></tr>"
+        "<tr><th>Remote head</th>"
+        f"<td><code>{_esc(stale.remote_head or 'unknown')}</code></td></tr>"
+        f"<tr><th>Stale</th><td>{_esc(stale.stale)}</td></tr>"
+        f"<tr><th>Determinable</th><td>{_esc(stale.determinable)}</td></tr>"
+        f"<tr><th>Mutation safe</th><td>{_esc(stale.mutation_safe)}</td></tr>"
+        "</table>"
+        f"{_reason_list(stale.reasons, empty='Runtime, checkout, and remote agree.')}"
+        "</section>"
+    )
+
+
+def _probe_error_card(snapshot: SystemHealthSnapshot) -> str:
+    if not snapshot.probe_errors:
+        return ""
+    return (
+        "<section class='health-card'>"
+        "<h3>Probe errors</h3>"
+        f"{_reason_list(snapshot.probe_errors, empty='')}"
+        "</section>"
+    )
+
+
+def _recovery_card() -> str:
+    """Sanctioned recovery pointers only — never a manual process kill (#630)."""
+    return (
+        "<section class='health-card'>"
+        "<h3>Recovery</h3>"
+        "<p class='muted'>This dashboard is read-only. Restart and reload "
+        "controls arrive in Phase 2 (#642); until then recovery runs through "
+        "the sanctioned client reconnect / operator restart path.</p>"
+        "<ul class='reasons'>"
+        "<li><a href='/runtime'>Runtime and session view</a> — active profile, "
+        "workflow hashes, and shell health.</li>"
+        "<li>Reconnect the MCP client from the IDE, then re-run the blocked "
+        "cycle. Never kill the daemon process manually: unmanaged kills are "
+        "recorded as runtime contamination (#630).</li>"
+        "<li>See <code>docs/webui-local-dev.md</code> for the documented "
+        "recovery sequence.</li>"
+        "</ul>"
+        "</section>"
+    )
+
+
+def render_system_health_page(snapshot: SystemHealthSnapshot) -> str:
+    """Render the full system-health dashboard body."""
+    return (
+        "<h2>System health</h2>"
+        "<p class='meta'>Read-only view of the Phase 1 system-health API "
+        "(<code>/api/v1/system/health</code>). Reload this page to refresh; "
+        "nothing here polls or mutates on your behalf.</p>"
+        f"{_readiness_card(snapshot)}"
+        f"{_stale_runtime_card(snapshot)}"
+        f"{_version_card(snapshot)}"
+        f"{_dependency_card(snapshot)}"
+        f"{_namespace_card(snapshot)}"
+        f"{_probe_error_card(snapshot)}"
+        f"{_recovery_card()}"
+    )