fix(tests): the repeat tail is the middle state now, not the opened one (#4100)

CI run 6943: 11 failures, two causes, both existing guards correctly catching
the behaviour change rather than defects in it.

TEN were `_SEEN_TAIL = "You saw it earlier this session"`. Every one of those
tests drives an arm with `exclude_rule_ids` alone — the NAMING ledger — which
since this change is the middle state, not the opened one. That is the whole
point of the step: `seen` stopped meaning "you saw it". The constant now holds
the middle tail, so each test keeps asserting exactly what it was written to
assert (a repeat gets a line distinct from a first surfacing) against the
wording that is now true.

Added `_HELD_TAIL` and a negative assertion with it: neither call names an
opened ledger, so neither may claim the session read anything. That catches
`held` defaulting true, which would have every repeat assert the strongest of
the three claims on no evidence — and none of the ten existing tests would
have noticed.

THE ELEVENTH was my own test edit being wrong, not the code. I asserted
`held_rule_ids` would appear in `re.findall(r"printf '([a-z_]+)=", defs)`, but
`scribe_held_query` spells it `printf '&held_rule_ids=`, and the leading `&`
means that regex never matches it. The regex enumerates SCOPE keys — the
alternatives that open a query — and the ledger key is appended to a query
that already has one. Two different contracts that happened to share a file,
so they are now asserted separately and the difference is written down.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01821k5B3Ysecp9fNYs92Kuy

tests/test_rule_usage_wiring.py

@@ -751,9 +751,14 @@ def test_the_hook_and_the_route_agree_on_every_parameter_name():
     # is read by a shared helper so its ageing and format cannot drift from the
     # naming ledger's, which means the key is spelled in defs rather than here.
     assert "scribe_held_query" in hook, "hook no longer sends the opened ledger"
-    assert set(re.findall(r"printf '([a-z_]+)=", defs)) == {
-        "repo", "project_id", "held_rule_ids",
-    }
+    assert set(re.findall(r"printf '([a-z_]+)=", defs)) == {"repo", "project_id"}
+    # Spelled with its own leading `&` because it is APPENDED to a query that
+    # already has a scope key, where the two above are alternatives that open
+    # one. Asserted separately for that reason: a scope key and a ledger key
+    # are different contracts that happen to share a file.
+    assert "printf '&held_rule_ids=" in defs, (
+        "the opened ledger's query key is no longer spelled in the helper"
+    )
 
     # Both scope keys are read by the shared _project_scope() helper, not inline.
     assert "_project_scope()" in handler
@@ -1141,7 +1146,14 @@ _HELD = fake_rule(
     when_to_apply="writing any call that crosses a process boundary",
 )
 _FRESH_TAIL = "not in this session's loaded set"
-_SEEN_TAIL = "You saw it earlier this session"
+# `seen` WITHOUT `held` is the middle state since #4100: an arm named this rule
+# earlier, and the session never opened it. Every test below drives the arms
+# with `exclude_rule_ids` alone — the naming ledger — so this is the tail they
+# produce, and it is the one that used to claim "You saw it earlier this
+# session" about a teaser nobody had read.
+_SEEN_TAIL = "Mentioned earlier this session but not opened"
+# The third state, reached only when the opened ledger names the rule too.
+_HELD_TAIL = "You opened it earlier this session"
 
 
 @pytest.mark.parametrize(("source", "run"), _ARMS, ids=["write_path", "pre_tool", "prompt"])
@@ -1194,6 +1206,12 @@ async def test_the_two_tails_are_distinguishable_and_say_the_true_one(source, ru
         f"in its loaded set"
     )
     assert fresh_ctx != seen_ctx, "the two tails collapsed into one"
+    # Neither call named an OPENED ledger, so neither may claim the session
+    # read anything (#4100). Catches `held` defaulting true, which would make
+    # every repeat assert the strongest of the three claims on no evidence.
+    assert _HELD_TAIL not in fresh_ctx and _HELD_TAIL not in seen_ctx, (
+        f"{source} said the session had opened a rule it was only shown"
+    )
 
 
 # ── the third axis: KIND (milestone 399) ────────────────────────────────