feat(lvl5): P1 — 5-rung ladder (L5=abra recipe lint) + de-capped level semantics

level.py: RUNGS += lint; statuses {pass,fail,skip,unver}; compute_level = max passed
rung with all below pass-or-skip (fail/unver block); cap_reason/capped DELETED.
harness/lint.py: lint executor — pristine scratch clone of the per-run tree at the
exact tested ref (mirror-origin + untracked-overlay pollution solved by context, no
rule filtered), PTY via script -qec, 60s hard budget, lint.txt artifact, table-parse
classifier (rc only signals FATA), unver on any non-run (never silent pass).
results.py: derive_rungs classifies every N/A source (structural/declared → skip,
else unver), lint rung + synthetic lint stage + lint block in results.json, schema 2,
cap fields removed. run_recipe_ci.py: lint call before tiers (double-wrapped,
verdict-neutral), badge = level only. card/dashboard: 0-5 ramp, cap line → 'level N
of {4|5}', unverified rows, badge number+colour only, lint.txt servable, old schema-1
artifacts render untouched. Unit suite rewritten: 245 passed on cc-ci venv.

tests/unit/test_dashboard.py

@@ -28,7 +28,6 @@ def _row(**kw):
         "ref": "db9a9502",
         "version": "db9a95024e9d",
         "level": 4,
-        "level_cap_reason": "",
         "has_screenshot": True,
         "flags": {"clean_teardown": True, "no_secret_leak": True},
         "finished": 0,
@@ -40,7 +39,7 @@ def _row(**kw):
 
 def test_level_color_ramp_and_fallback():
     assert dashboard.level_color(0) == "#e5534b"
-    assert dashboard.level_color(6) == "#3fb950"
+    assert dashboard.level_color(5) == "#3fb950"  # full 5-rung climb (phase lvl5)
     assert dashboard.level_color(4) == "#a0b93f"
     assert dashboard.level_color(99) == "#8b949e"
     assert dashboard.level_color(None) == "#8b949e"
@@ -61,20 +60,12 @@ def test_overview_grid_mirrors_results():
 def test_overview_never_greener_than_data():
     # A failed run at level 0 must show level 0 + the failure pill — never a green/high level.
     out = dashboard.render_overview(
-        [
-            _row(
-                status="failure",
-                level=0,
-                has_screenshot=False,
-                flags={},
-                level_cap_reason="L1 install FAILED",
-            )
-        ]
+        [_row(status="failure", level=0, has_screenshot=False, flags={})]
     )
     assert "level 0" in out
     assert dashboard.level_color(0) in out  # red
     assert dashboard._COLORS["failure"] in out
-    assert "level 4" not in out and "level 5" not in out and "level 6" not in out
+    assert "level 4" not in out and "level 5" not in out
     assert "no screenshot" in out  # placeholder, no broken image
 
 
@@ -104,7 +95,6 @@ def test_build_row_projects_results(monkeypatch):
         lambda n: {
             "version": "1.2.3",
             "level": 2,
-            "level_cap_reason": "cap",
             "screenshot": "screenshot.png",
             "flags": {"clean_teardown": True},
         },
@@ -123,6 +113,38 @@ def test_build_row_projects_results(monkeypatch):
     assert r["url"].endswith("/cc-ci/7")
 
 
+def test_build_row_old_schema1_artifact_renders(monkeypatch):
+    # History compatibility (phase lvl5): pre-lvl5 results.json still carries cap fields and a
+    # 4-rung ladder — it must project + render without KeyError, level shown VERBATIM (no
+    # retroactive relabeling), and the old cap text simply isn't resurfaced anywhere.
+    monkeypatch.setattr(
+        dashboard,
+        "_results_for",
+        lambda n: {
+            "schema": 1,
+            "version": "0.9.1",
+            "level": 2,
+            "level_cap_reason": "L3 backup/restore (data integrity) N/A",
+            "level_cap_rung": "backup_restore",
+            "screenshot": "screenshot.png",
+            "flags": {"clean_teardown": True, "no_secret_leak": True},
+        },
+    )
+    b = {
+        "number": 11,
+        "status": "success",
+        "event": "custom",
+        "params": {"RECIPE": "legacy", "REF": "abc123"},
+        "finished": 5,
+    }
+    r = dashboard._build_row(b)
+    out = dashboard.render_overview([r])
+    assert "level 2" in out and dashboard.level_color(2) in out
+    assert "N/A" not in out and "capped" not in out  # cap language gone from the surface
+    hist = dashboard.render_history("legacy", [r])
+    assert "L2" in hist
+
+
 def test_build_row_degrades_without_results(monkeypatch):
     # No results.json (e.g. an old run): grid still renders from Drone fields, level absent.
     monkeypatch.setattr(dashboard, "_results_for", lambda n: {})