docs(6209): forge, dedup, tuning, registry, reply shapes and discipline, checkpoint, lesson kind tests

Eight more test files state their properties without issue, milestone,
rule and decision numbers. The tuning and suspension notes describe the
symptom a shipped default or a late ledger produces instead of one
install's dated readings; the reply-discipline and checkpoint docstrings
state the failure they prevent instead of the session that measured it.
test_empty_selector_is_the_rule_115_baseline is renamed for what it
checks: the no-forge baseline.

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

tests/test_retrieval_tuning.py

@@ -1,11 +1,10 @@
-"""Moving a floor, and the reason that has to come with it (#4102).
+"""Moving a floor, and the reason that has to come with it.
 
 WHY THIS EXISTS
 
-The operator handed the dial to the model: *"the user should be able to touch it
-but the model should be the thing handling it 9 times out of 10."* Everything
-here guards the half of that sentence people skip — the operator still has to be
-able to see what was done on their behalf and disagree with it.
+The model moves these dials most of the time, and a person can too. Everything
+here guards the half of that arrangement people skip — the person still has to
+be able to see what was done on their behalf and disagree with it.
 
 WHAT THIS PINS
 
@@ -20,7 +19,7 @@ WHAT THIS PINS
      question anyone asks of a surface behaving oddly.
   3. **A clamp is reported, never swallowed.** A caller that believes it set 1.4
      will read the next telemetry as evidence about a bar that was never in
-     force — the same class of error as #3739, one layer up.
+     force.
   4. **An unknown surface is refused before anything is written.** Settings keys
      are free-form strings, so a typo'd surface would write a key nothing reads:
      a change that reports success and alters nothing.
@@ -167,7 +166,7 @@ async def test_an_unknown_actor_is_refused():
 
 
 def test_the_tool_teaches_reading_the_records_not_the_percentile():
-    """The contract an agent actually reads (rule 167).
+    """The contract an agent actually reads.
 
     The failure this prevents is a model moving a bar because `near_misses.p90`
     sat close to it. That has been measured pointing the wrong way — 69 declines
@@ -198,20 +197,19 @@ def test_every_tool_in_the_module_is_registered():
     ]
 
 
-# ── record_release_defaults / floor_moves_since (#4225) ───────────────────
+# ── record_release_defaults / floor_moves_since ───────────────────────────
 #
 # THE HOLE THESE FILL. This table records dial turns — a person or a model
-# choosing a number. It was silent about the other way a floor moves: somebody
-# edits `floor_default` in the registry and ships it. That change is invisible
-# to every consumer of this table, and one consumer is `band_hugs_floor`, which
-# compares a band against a floor and could not notice they came from different
-# regimes.
+# choosing a number. The other way a floor moves is somebody editing
+# `floor_default` in the registry and shipping it, and without a release row
+# that change is invisible to every consumer of this table — including
+# `band_hugs_floor`, which compares a band against a floor and cannot notice
+# they came from different regimes.
 #
-# Measured on the instance that found it: `write_path_rule` went 0.68 -> 0.72
-# on 2026-09-02 as a shipped default, so a 30-day window opening 2026-08-22
-# held six days of calls made under the old bar. The readout reported the band
-# sitting "-0.0216 above" its floor — which is what a two-population comparison
-# looks like when it finally says so out loud.
+# The symptom: a window that spans a shipped default change holds calls made
+# under the old bar, and the readout reports the band a negative distance
+# "above" its floor — what a two-population comparison looks like when it
+# finally says so out loud.
 
 
 def _release_rows(rows):
@@ -350,12 +348,10 @@ async def test_a_baseline_is_not_reported_as_a_floor_move():
 # WATCHING. Before an arm's first row there is nothing to move, nothing to
 # report, and no way to tell a steady floor from an unrecorded change.
 #
-# Measured the day the ledger was seeded on this instance: its earliest event
-# of any kind is 2026-09-17, its `write_path_rule` floor rows begin at
-# 2026-09-21, and a 30-day window opening 2026-08-22 reported that arm's band
-# sitting "-0.0208 above" its floor. That negative distance is the documented
-# tell of a raise inside the window — announced by the check the suspension
-# was built to stop, because the suspension had nothing to read.
+# The symptom: a window that opens before an arm's first floor row reports the
+# band a negative distance "above" its floor. That is the documented tell of a
+# raise inside the window — announced by the check the suspension exists to
+# stop, because the suspension has nothing to read.
 
 
 def _gap_rows(rows):