fix(html): use relative asset and nav paths for subpath deploys

AGENTS.md

@@ -678,6 +678,7 @@ The static site uses a modern, responsive design with the following features:
 - **Repeater pages at root**: `/day.html`, `/week.html`, etc. (entry point)
 - **Companion pages**: `/companion/day.html`, `/companion/week.html`, etc.
 - **`.htaccess`**: Sets `DirectoryIndex day.html` so `/` loads repeater day view
+- **Relative links**: All internal navigation and static asset references are relative (no leading `/`) so the dashboard can be served from a reverse-proxy subpath.
 
 ### Page Layout
 1. **Header**: Site branding, node name, pubkey prefix, status indicator, last updated time

src/meshmon/html.py

@@ -480,6 +480,7 @@ def build_chart_groups(
     role: str,
     period: str,
     chart_stats: dict | None = None,
+    asset_prefix: str = "",
 ) -> list[dict]:
     """Build chart groups for template.
 
@@ -490,6 +491,7 @@ def build_chart_groups(
         role: "companion" or "repeater"
         period: Time period ("day", "week", etc.)
         chart_stats: Stats dict from chart_stats.json (optional)
+        asset_prefix: Relative path prefix to reach /assets from page location
     """
     cfg = get_config()
     groups_config = REPEATER_CHART_GROUPS if role == "repeater" else COMPANION_CHART_GROUPS
@@ -551,8 +553,9 @@ def build_chart_groups(
                 chart_data["use_svg"] = True
             else:
                 # Fallback to PNG paths
-                chart_data["src_light"] = f"/assets/{role}/{metric}_{period}_light.png"
-                chart_data["src_dark"] = f"/assets/{role}/{metric}_{period}_dark.png"
+                asset_base = f"{asset_prefix}assets/{role}/"
+                chart_data["src_light"] = f"{asset_base}{metric}_{period}_light.png"
+                chart_data["src_dark"] = f"{asset_base}{metric}_{period}_dark.png"
                 chart_data["use_svg"] = False
 
             charts.append(chart_data)
@@ -614,7 +617,10 @@ def build_page_context(
 
     # Load chart stats and build chart groups
     chart_stats = load_chart_stats(role)
-    chart_groups = build_chart_groups(role, period, chart_stats)
+
+    # Relative path prefixes (avoid absolute paths for subpath deployments)
+    css_path = "" if at_root else "../"
+    asset_prefix = "" if at_root else "../"
 
     # Period config
     page_title, page_subtitle = PERIOD_CONFIG.get(period, ("Observations", "Radio telemetry"))
@@ -634,9 +640,18 @@ def build_page_context(
         ),
     }
 
-    # CSS and link paths - depend on whether we're at root or in /companion/
-    css_path = "/" if at_root else "../"
-    base_path = "" if at_root else "/companion"
+    chart_groups = build_chart_groups(role, period, chart_stats, asset_prefix=asset_prefix)
+
+    # Navigation links depend on whether we're at root or in /companion/
+    base_path = ""
+    if at_root:
+        repeater_link = "day.html"
+        companion_link = "companion/day.html"
+        reports_link = "reports/"
+    else:
+        repeater_link = "../day.html"
+        companion_link = "day.html"
+        reports_link = "../reports/"
 
     return {
         # Page meta
@@ -665,9 +680,9 @@ def build_page_context(
         # Navigation
         "period": period,
         "base_path": base_path,
-        "repeater_link": f"{css_path}day.html",
-        "companion_link": f"{css_path}companion/day.html",
-        "reports_link": f"{css_path}reports/",
+        "repeater_link": repeater_link,
+        "companion_link": companion_link,
+        "reports_link": reports_link,
 
         # Timestamps
         "last_updated": last_updated,

src/meshmon/templates/node.html

@@ -113,10 +113,10 @@
   <main class="main-content">
     <!-- Period Navigation -->
     <nav class="period-nav">
-      <a href="{{ base_path }}/day.html"{% if period == 'day' %} class="active"{% endif %}>Day</a>
-      <a href="{{ base_path }}/week.html"{% if period == 'week' %} class="active"{% endif %}>Week</a>
-      <a href="{{ base_path }}/month.html"{% if period == 'month' %} class="active"{% endif %}>Month</a>
-      <a href="{{ base_path }}/year.html"{% if period == 'year' %} class="active"{% endif %}>Year</a>
+      <a href="{{ base_path }}day.html"{% if period == 'day' %} class="active"{% endif %}>Day</a>
+      <a href="{{ base_path }}week.html"{% if period == 'week' %} class="active"{% endif %}>Week</a>
+      <a href="{{ base_path }}month.html"{% if period == 'month' %} class="active"{% endif %}>Month</a>
+      <a href="{{ base_path }}year.html"{% if period == 'year' %} class="active"{% endif %}>Year</a>
     </nav>
 
     <header class="page-header">

tests/html/test_page_context.py

@@ -229,5 +229,28 @@ class TestBuildPageContext:
             at_root=False,
         )
 
-        assert root_context["css_path"] == "/"
+        assert root_context["css_path"] == ""
         assert non_root_context["css_path"] == "../"
+
+    def test_links_use_relative_paths(self, configured_env, sample_row):
+        """Navigation and asset links are relative for subpath deployments."""
+        root_context = build_page_context(
+            role="repeater",
+            period="day",
+            row=sample_row,
+            at_root=True,
+        )
+        non_root_context = build_page_context(
+            role="companion",
+            period="day",
+            row=sample_row,
+            at_root=False,
+        )
+
+        assert root_context["repeater_link"] == "day.html"
+        assert root_context["companion_link"] == "companion/day.html"
+        assert root_context["reports_link"] == "reports/"
+
+        assert non_root_context["repeater_link"] == "../day.html"
+        assert non_root_context["companion_link"] == "day.html"
+        assert non_root_context["reports_link"] == "../reports/"

tests/html/test_write_site.py

@@ -266,7 +266,8 @@ class TestHtmlOutput:
 
         content = (out_dir / "day.html").read_text()
 
-        assert "styles.css" in content
+        assert 'href="styles.css"' in content
+        assert 'href="/styles.css"' not in content
 
     def test_companion_pages_relative_css(self, html_env, metrics_rows):
         """Companion pages use relative path to CSS."""
@@ -277,4 +278,5 @@ class TestHtmlOutput:
         content = (out_dir / "companion" / "day.html").read_text()
 
         # Should reference parent directory CSS
-        assert "../styles.css" in content or "styles.css" in content
+        assert 'href="../styles.css"' in content
+        assert 'href="/styles.css"' not in content

tests/unit/test_html_builders.py

@@ -6,6 +6,7 @@ from meshmon.html import (
     PERIOD_CONFIG,
     REPEATER_CHART_GROUPS,
     _build_traffic_table_rows,
+    build_chart_groups,
     build_companion_metrics,
     build_node_details,
     build_radio_config,
@@ -457,3 +458,32 @@ class TestChartGroupConstants:
         for _period, (title, subtitle) in PERIOD_CONFIG.items():
             assert isinstance(title, str)
             assert isinstance(subtitle, str)
+
+
+class TestBuildChartGroups:
+    """Tests for build_chart_groups."""
+
+    def test_png_paths_use_relative_prefix(self, configured_env):
+        """PNG fallback paths respect provided asset prefix."""
+        out_dir = configured_env["out_dir"]
+        asset_dir = out_dir / "assets" / "repeater"
+        asset_dir.mkdir(parents=True, exist_ok=True)
+        (asset_dir / "bat_day_light.png").write_bytes(b"fake")
+
+        groups = build_chart_groups(
+            role="repeater",
+            period="day",
+            chart_stats={},
+            asset_prefix="../",
+        )
+
+        chart = next(
+            chart
+            for group in groups
+            for chart in group["charts"]
+            if chart["metric"] == "bat"
+        )
+
+        assert chart["use_svg"] is False
+        assert chart["src_light"] == "../assets/repeater/bat_day_light.png"
+        assert chart["src_dark"] == "../assets/repeater/bat_day_dark.png"