test(search): name the in-brain swap-race tests after what they sample

Review of #172 (rule 9): "LeaksNothing" claims more than a 1.5s
sampled race can prove -- the same overclaim this PR removes from the
"Never" names. Renamed to DoesNotReturn...DuringASampledSwapRace,
and the brainfstest doc now says the target may be inside the brain
(#171) and that observation is over a sampled window.

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

ingestion/internal/brainfs/brainfstest/brainfstest.go

@@ -1,8 +1,10 @@
 // Package brainfstest is the shared harness for hyperguild#157's swap-race
-// tests: it keeps swapping a regular note, a symlink to an outside file, or a
+// tests: it keeps swapping a regular note, a symlink to a sentinel target file
-// FIFO (with a writer held open) into a path while a reader under test loops.
+// (outside the brain, or inside it for hyperguild#171), or a FIFO (with a
-// It observes two things: no sentinel byte from the outside file reaches the
+// writer held open) into a path while a reader under test loops.
-// reader's output, and the reader returns within a timeout. It does not cover
+// It observes two things, over a sampled window only: no sentinel byte from
+// the target reaches the reader's output, and the reader returns within a
+// timeout. It does not cover
 // hard links, other paths into the reader, or races it does not generate.
 package brainfstest
 
@@ -18,7 +20,7 @@ import (
 	"time"
 )
 
-// Sentinel marks the outside file's contents.
+// Sentinel marks the target file's contents.
 const Sentinel = "zqbrainfssentinelonefiftyseven"
 
 // outsideContent carries Sentinel in every field a reader might extract: the

ingestion/internal/search/brainroot_test.go

@@ -184,7 +184,7 @@ func inBrainTarget(t *testing.T, brain string) string {
 	return brainfstest.WriteSentinelAt(t, filepath.Join(brain, "raw", "s.md"))
 }
 
-func TestQueryLeaksNothingFromAnInBrainTargetUnderASymlinkSwapRace(t *testing.T) {
+func TestQueryDoesNotReturnAnInBrainSymlinkTargetDuringASampledSwapRace(t *testing.T) {
 	brain, facts, _ := searchBrain(t)
 	target := inBrainTarget(t, brain)
 	read := func() string {
@@ -200,7 +200,7 @@ func TestQueryLeaksNothingFromAnInBrainTargetUnderASymlinkSwapRace(t *testing.T)
 	assert.NotContains(t, read(), brainfstest.Sentinel, "static in-brain link")
 }
 
-func TestHydrateRefusesAnInBrainSymlinkAndLeaksNothingUnderASwapRace(t *testing.T) {
+func TestHydrateRefusesAnInBrainSymlinkAndDoesNotReturnItsTargetDuringASampledSwapRace(t *testing.T) {
 	brain, facts, _ := searchBrain(t)
 	target := inBrainTarget(t, brain)
 	require.NoError(t, os.Symlink(filepath.Join("..", "..", "..", "raw", "s.md"), filepath.Join(facts, "inlink.md")))