docs(6209): wide net, startup, stamps, slippage, miss route and parity tests

Eight more test files state the property they pin as a present-tense
fact. Incident narratives (a dated storage stall, a week of zero tuning
events, a two-project poisoned ledger, a twenty-site owner audit) become
the failure shape each test defends; one-install figures that name a rule
become a general worked example with the calibration numbers kept. The
family-grouping regression guard is renamed for what it checks.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

tests/test_plugin_shipped_set.py

@@ -1,15 +1,14 @@
 """One definition of what SHIPS in the plugin, and the drift guards on it.
 
-WHAT THIS IS ABOUT (#3127 §3, milestone 334 step 2). Scribe publishes two
-artifacts. `plugin/` is not in the Docker image — installs fetch it from this
+WHAT THIS IS ABOUT. Scribe publishes two artifacts. `plugin/` is not in the Docker image — installs fetch it from this
 repo through `.claude-plugin/marketplace.json`, so **a push IS the release**,
 with no build step in between. That makes "which files reach an install?" a
-question with real consequences, and it has been answered wrong twice:
+question with real consequences, and it can be answered wrong two ways:
 
-  - #2198 — `plugin/**` was in no `paths:` filter, so four broken hooks
-    reached live installs having triggered no CI at all.
-  - #2209 — the fix for that shipped and still could not reach an install,
-    because the manifest version had not moved.
+  - a shipped path in no `paths:` filter reaches live installs having
+    triggered no CI at all;
+  - a fix that ships without the manifest version moving cannot reach an
+    install.
 
 The set lives in `scripts/check_plugin.py`. Its second consumer is the
 workflow's `paths:` trigger, which is YAML and cannot import Python — so the
@@ -66,7 +65,7 @@ def test_every_shipped_path_exists():
 
 
 def test_every_shipped_path_triggers_ci():
-    """#2198's exact hole, stated as an assertion.
+    """A shipped path that runs no CI, stated as an assertion.
 
     Directional on purpose: the trigger is a superset (it also fires on
     `src/**`, `tests/**` and friends). What must never happen is a path that
@@ -77,7 +76,7 @@ def test_every_shipped_path_triggers_ci():
         covered = any(t == path or t.startswith(f"{path}/") for t in triggers)
         assert covered, (
             f"{path} ships to installs but no `paths:` entry covers it — "
-            f"changes there would reach a live install having run no CI (#2198)"
+            f"changes there would reach a live install having run no CI"
         )
 
 
@@ -94,10 +93,8 @@ def test_the_checker_itself_triggers_ci():
 def test_no_trigger_path_names_something_that_does_not_exist():
     """The guard that catches scaffolding outliving its subsystem.
 
-    `fable-mcp/**` sat in this list for three months after the directory was
-    deleted (commit 91bafb6, 2026-05-27), and `assets/**` named a path that
-    never existed at all. Neither ever failed anything — a `paths:` entry
-    matching nothing simply never fires — which is precisely why a list kept
+    A `paths:` entry matching nothing simply never fires, so an entry for a
+    deleted directory, or for a path that never existed, fails nothing — which is precisely why a list kept
     by hand drifts and nobody finds out.
     """
     missing = [
@@ -114,7 +111,7 @@ def test_every_deriver_exists():
     """§3's table, kept honest.
 
     The point of the table is that the next artifact is a one-line addition
-    (milestone 334 step 3 adds the plugin's mint script). A row pointing at a
+    (the plugin's mint script is one). A row pointing at a
     file that has moved would make the table read as complete when it is not.
     """
     for path, artifacts in DERIVERS.items():
@@ -162,7 +159,7 @@ def test_every_OTHER_manifest_field_still_demands_a_new_version(field, value):
     `plugin.json` carries description, mcpServers and userConfig alongside the
     version, and all of them reach an install. Excluding the file wholesale
     would mean a userConfig-only edit computes an unchanged version and never
-    refreshes — #2209 again, with a narrower trigger and the same silence.
+    refreshes — a fix that cannot reach an install, in silence.
     """
     assert manifest_differs_beyond_version(manifest(**{field: value}), manifest()) is True
 
@@ -181,7 +178,7 @@ def test_reformatting_is_not_a_content_change():
 def test_unreadable_input_demands_a_new_version(bad):
     """The conservative direction, chosen deliberately.
 
-    A spurious bump costs one cache refresh. A missed one is #2209 — the fix
+    A spurious bump costs one cache refresh. A missed one means the fix
     reaches the repo and stops there, and the only detector is a human saying
     "I don't think it updated."
     """
@@ -238,9 +235,8 @@ def test_shipped_content_changed_reports_a_hook_edit_as_changed(monkeypatch):
 def test_a_failed_diff_is_None_and_never_False(monkeypatch):
     """Could-not-tell and nothing-changed must not collapse into one value.
 
-    #2663 is the precedent: a read that failed inside a broad except reported
-    the same zero as a genuinely empty window, and every counter read zero for
-    weeks with nothing to distinguish the two.
+    A read that fails inside a broad except and reports the same zero as a
+    genuinely empty window leaves nothing to distinguish the two.
     """
     from scripts import check_plugin