docs(6209): twelve more test files say which behaviour they pin

shape ledger, MCP projects/search/rulebooks tools, backup, chunking,
plugin context, derived mirror, rule band, shape form gate, plugin
version mint and note usage tests drop issue, milestone and rule numbers,
dates and one-install figures from docstrings, comments and messages.
Three shape-form-gate test names that told the discovery story now name
the property: a registry module's helpers are not service functions, the
divergence gate silences only a family contradiction, and callable helpers
beside a callable canon still prompt. The rulebook tool-count comment that
logged each milestone's additions is replaced by the reason it is a count.

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

tests/test_plugin_version_mint.py

@@ -1,6 +1,6 @@
 """The plugin's version is MINTED, and CI is the control that it moved.
 
-WHAT THIS IS ABOUT (milestone 334 step 3). `plugin/` ships straight from this
+WHAT THIS IS ABOUT. `plugin/` ships straight from this
 git repo — no build step, so no moment at which CI could stamp a version in.
 The value is therefore minted by a script before the commit, and CI's job is
 not to produce it but to prove it moved when it had to.
@@ -11,15 +11,15 @@ from different clocks, on purpose:
     server image   name from COMMIT time, ordering key from BUILD time
     plugin         one value, from MINT time
 
-#3127 §2 prescribes commit time so two lanes building one source report one
+The server uses commit time so two lanes building one source report one
 string. The plugin has one lane and no build, so that reason does not reach
 it. "Let's make these consistent" is the obvious tidy-up and it breaks
 whichever artifact loses — which is why the difference is pinned here rather
 than only explained in a comment.
 
 The trade mint time makes — you cannot recompute the value from history, only
-verify it moved — is acceptable ONLY because #3325 established that the
-installer's refresh test is `===` with no ordering anywhere. Where a
+verify it moved — is acceptable ONLY because the installer's refresh test
+is `===` with no ordering anywhere. Where a
 comparator orders, an unreproducible version would be unverifiable too.
 """
 import ast
@@ -57,7 +57,7 @@ def fake_manifest(version: str = "2026.09.01.2252") -> str:
 
 
 @pytest.mark.parametrize("when,expected", [
-    # THE midnight case, which #3127 checklist 10 names by hand. An unpadded
+    # THE midnight case. An unpadded
     # `%-H%M` renders this hour as `0` and silently shortens the string.
     (datetime(2026, 1, 5, 0, 0, tzinfo=timezone.utc), "2026.01.05.0000"),
     (datetime(2026, 1, 5, 0, 9, tzinfo=timezone.utc), "2026.01.05.0009"),
@@ -150,7 +150,7 @@ def test_the_rewrite_refuses_TWO_version_lines():
 
 
 def test_the_mint_script_is_version_relevant():
-    """#3127 §3's asymmetry. A change to how the version is COMPUTED is
+    """The deriver's asymmetry. A change to how the version is COMPUTED is
     compared against nothing — leave the deriver out of the set and a format
     change never forces a re-mint, so the manifest keeps a value in the old
     format indefinitely and nothing says so."""
@@ -189,7 +189,7 @@ def run_check(here: str, there: str | None, changed_paths: list[str], monkeypatc
 
 
 def test_content_changed_and_the_version_did_not_FAILS(monkeypatch):
-    """#2209, exactly. The headline, and the only reason the check exists."""
+    """The headline, and the only reason the check exists."""
     failures = run_check(
         "2026.09.01.2252", "2026.09.01.2252",
         ["plugin/hooks/scribe_session_context.sh"], monkeypatch,
@@ -209,7 +209,7 @@ def test_content_changed_and_the_version_moved_PASSES(monkeypatch):
 def test_a_version_that_is_not_the_canonical_shape_FAILS(monkeypatch):
     """`K4` returns the manifest string verbatim, so a malformed value is not
     rejected by the installer — it either sorts as an ordinary string or, when
-    unreadable, forces a reinstall every session. Neither is loud (#3325)."""
+    unreadable, forces a reinstall every session. Neither is loud."""
     failures = run_check("0.1.48", "0.1.47", [], monkeypatch)
     assert len(failures) == 1
     assert "not YYYY.MM.DD.HHMM" in failures[0]
@@ -218,7 +218,7 @@ def test_a_version_that_is_not_the_canonical_shape_FAILS(monkeypatch):
 @pytest.mark.parametrize("bad", ["2026.9.1.2252", "2026.09.01.252", "2026.09.01"])
 def test_an_UNPADDED_or_short_version_FAILS(bad, monkeypatch):
     """The padding is the contract, not cosmetics — one shape for every version
-    in the family (#3127 checklist 10)."""
+    in the family."""
     assert run_check(bad, "2026.08.30.1200", [], monkeypatch) != []
 
 
@@ -250,7 +250,7 @@ def test_a_version_that_moved_with_no_content_change_is_NOT_a_failure(monkeypatc
 
 def test_a_failed_diff_FAILS_rather_than_passing_quietly(monkeypatch):
     """A check that cannot run must not report the same thing as a check that
-    passed — #2663's lesson, and the reason this file's siblings exist.
+    passed.
 
     `rev-parse` is stubbed to SUCCEED so only the diff fails. Failing every git
     call would trip the base-branch guard first and this would pass while
@@ -280,13 +280,8 @@ def test_the_shipped_manifest_carries_a_minted_version():
 
 
 def test_the_session_context_hook_still_reads_the_version_field():
-    """The marker #2220 asked for. The value's SHAPE changed, not the field or
-    its reader — if this had to move, the derivation went somewhere it should
-    not have.
-
-    The READER changed once, in #4107: `jq -r '.version'` became
-    `scribe_json_pick ... '.version'` when the hooks stopped depending on jq.
-    What this pins is unchanged — that the hook still reads `.version` out of
-    the manifest rather than deriving the string some other way."""
+    """The hook reads `.version` out of the manifest rather than deriving the
+    string some other way — if this has to move, the derivation went
+    somewhere it should not have."""
     hook = (check_plugin.HOOKS_DIR / "scribe_session_context.sh").read_text()
     assert re.search(r"scribe_json_pick[^\n]*'\.version'", hook)