fix(agent): "In short supply" is not a short version

Round 5. Two of the eight findings are the em-dash mid-rune slice, which
the orientation matrix had already caught and fixed in 285789c before
this round returned — the harness doing the reviewers' job, which is the
point of it.

Of the rest:

**A marker phrase can open a sentence and still be prose** (kimi).
"That's the chain above. In short supply of alternatives, we went with
B." opens a sentence with "In short" and announces nothing. The marker
must now be followed by the delimiter a model puts after a real
announcement — the colon in "Short version:", the comma in "In short,".
No delimiter means no match, which keeps the terminal: fails closed.

Adding that made the sentence-opening anchor look redundant — a
break-check that removed it survived, because every mid-sentence case in
the table was by then rejected for want of a delimiter. It is not
redundant: "…, and in short, we went with B" is a clause continuation
with a comma. The missing thing was a case for what the anchor alone
does, not the anchor.

**backRefHeadChars was named for the wrong family** (opus; sonnet raised
the same constant from the other side). It is applied only to the
deictic offset test, never to backRefRe. Renamed abovePointerHeadChars.
It stays defined as `= weakFinalMaxChars` rather than inlined, because an
earlier round asked for exactly that linkage and the reason still holds.

**The clause-boundary comment narrated my review history** (opus) — the
same class of finding I took two rounds ago and then reintroduced one
comment over. Rewritten as behaviour, pointing at the matrix.

**analysis1611 was a function returning a constant string** (sonnet) —
now a var.

Accepted, not fixed: a comparative "above," plus a sentence-opening
marker can still reach isSummaryCloser. That needs the comparative false
positive, a real marker, a terminal under 300 bytes, and a same-turn
prior at least 3x longer, all at once; the dwarf ratio is the backstop
and no lexical test separates the comparative from the deictic.

Break-check: seventeen mutations, each killed by a named test.

agent/finalize.go

@@ -161,7 +161,7 @@ func pointsAbove(t string) bool { return aboveRefLoc(t) != nil }
 // bareAbovePointer cannot disagree about what counts as a pointer.
 func aboveRefLoc(t string) []int {
 	loc := aboveRefRe.FindStringIndex(t)
-	if loc == nil || loc[0] > backRefHeadChars {
+	if loc == nil || loc[0] > abovePointerHeadChars {
 		return nil
 	}
 	return loc
@@ -204,12 +204,11 @@ func bareAbovePointer(t string) bool {
 
 // clauseBoundaryChars ends the clause the reference belongs to. Commas,
 // semicolons, colons and dashes are in it, not just sentence terminators,
-// because the answer can share the reference's SENTENCE: "Ship Tuesday, as
-// shown above." is a decision plus a pointer, and cutting back only to the
-// previous full stop swallowed the decision and made the whole thing look
-// bare. That is the same defect as treating a pointer as disposable because
-// something followed it — mirrored, and it survived a round of review because
-// every case I had written put the answer AFTER the pointer.
+// because the answer can share the reference's SENTENCE — "Ship Tuesday, as
+// shown above." is a decision plus a pointer, and cutting back to the previous
+// full stop would swallow the decision and make the whole terminal look bare.
+// Content on either side of the pointer disqualifies it equally; see
+// TestBareAbovePointerOrientations, which checks every placement.
 const clauseBoundaryChars = ".!?\n,;:—"
 
 // pointerResidueCutset is trimmed from both ends of what survives cutting the
@@ -238,12 +237,22 @@ var bareRemainderRe = regexp.MustCompile(`(?i)^(` + fillerWords + fillerSep + `*
 // comment explains: a user who asked for brevity is answered with exactly that
 // shape.
 //
-// The marker must OPEN a sentence. Mid-sentence the same words are ordinary
-// prose carrying new content — "Given the analysis above, the bottom line is
-// that we need a different vendor" states a conclusion, it does not announce a
-// condensation — and treating that as disposable is the very failure the
-// two-part test exists to prevent.
-var compressionMarkerRe = regexp.MustCompile(`(?i)(^|[.!?:;—]\s*|\n\s*)(short version|shorter version|short answer|tl;?dr|in short|in brief|in summary|in sum|bottom line|net[- ]net|the gist)\b`)
+// The marker must OPEN a sentence AND be followed by a delimiter — the colon
+// or comma a model puts after it when it is genuinely introducing the short
+// form. Both halves are needed against a different failure each:
+//
+//   - Mid-sentence the same words are ordinary prose carrying new content.
+//     "Given the analysis above, the bottom line is that we need a different
+//     vendor" states a conclusion; it does not announce a condensation.
+//   - At a sentence opening the words can still run on into ordinary prose.
+//     "In short supply of alternatives, we went with B" opens a sentence with
+//     "In short" and is not a summary at all.
+//
+// A marker with no delimiter ("In short we chose B") is not matched, which
+// fails closed: the terminal is kept, which is today's behaviour.
+var compressionMarkerRe = regexp.MustCompile(`(?i)(^|[.!?:;—]\s*|\n\s*)` +
+	`(short version|shorter version|short answer|tl;?dr|in short|in brief|in summary|in sum|bottom line|net[- ]net|the gist)` +
+	`\s*([:,—-]|$)`)
 
 // summaryCloserRe matches a terminal turn that OPENS with a bookkeeping
 // acknowledgment of the citation round — "Citations are logged.", "Sources
@@ -319,15 +328,19 @@ const (
 	// genuine final answer that merely contains "as I said" mid-sentence is
 	// longer than this, so it is never treated as weak.
 	weakFinalMaxChars = 120
-	// backRefHeadChars bounds how far into the terminal a deictic "above" may
-	// sit and still read as pointing OUTSIDE this message (see pointsAbove).
-	// It IS weakFinalMaxChars — the same guard ("there is not enough text
+	// abovePointerHeadChars bounds how far into the terminal a deictic "above"
+	// may sit and still read as pointing OUTSIDE this message (see
+	// pointsAbove). It applies to the deictic family only — backRefRe's fixed
+	// phrases are matched anywhere under the weak cap — so it is named for the
+	// pointer, not for the back-reference family as a whole.
+	//
+	// It IS weakFinalMaxChars: the same guard ("there is not enough text
 	// before the reference for it to be pointing at content inside this
 	// turn"), expressed as an offset because a summary closer carries a
 	// compression AFTER the pointer and so is not itself short. Defined by
-	// reference, not by repeating the literal: tuning the weak cap without the
-	// offset following it would split one rule into two.
-	backRefHeadChars = weakFinalMaxChars
+	// reference rather than by repeating the literal, because tuning the weak
+	// cap without the offset following it would split one rule into two.
+	abovePointerHeadChars = weakFinalMaxChars
 	// recoverMinChars: a prior assistant turn this long is treated as a real
 	// answer regardless of how it opens (the preamble filter is not applied at
 	// this length — see isSubstantiveAnswer).

agent/finalize_test.go

@@ -73,9 +73,7 @@ const closer1611 = "Done — that's the full chain above. Short version: it's no
 // analysis1611 stands in for that run's front-loaded analysis: long enough to
 // dwarf closer1611 (>3x its 220 bytes). Shared by the finalOutput table and
 // the end-to-end Run test so the two cannot drift apart.
-func analysis1611() string {
-	return strings.TrimSpace(strings.Repeat("The break was the Iran strikes, then the Epstein files. ", 12))
-}
+var analysis1611 = strings.TrimSpace(strings.Repeat("The break was the Iran strikes, then the Epstein files. ", 12))
 
 func TestPointsAbove(t *testing.T) {
 	cases := []struct {
@@ -112,9 +110,9 @@ func TestPointsAbove(t *testing.T) {
 		{"no-above-at-all", "42", false},
 		{"empty", "", false},
 
-		// Offset bound: past backRefHeadChars there IS enough text before the
+		// Offset bound: past abovePointerHeadChars there IS enough text before the
 		// reference for it to be pointing inside this same message. The
-		// lengths are LITERALS, not backRefHeadChars +/- n: a case sized from
+		// lengths are LITERALS, not abovePointerHeadChars +/- n: a case sized from
 		// the constant it is meant to pin moves with it, and a break-check
 		// that widened the bound to 100000 sailed straight through.
 		{"late-reference-not-a-pointer", strings.Repeat("x", 200) + " as shown above.", false},
@@ -133,12 +131,12 @@ func TestPointsAbove(t *testing.T) {
 		})
 	}
 
-	// The two bounds are ONE guard expressed two ways (see backRefHeadChars).
+	// The two bounds are ONE guard expressed two ways (see abovePointerHeadChars).
 	// Pinned here so decoupling them is a test failure, not a silent drift.
-	if backRefHeadChars != weakFinalMaxChars {
-		t.Errorf("backRefHeadChars = %d, weakFinalMaxChars = %d: the offset bound and the "+
+	if abovePointerHeadChars != weakFinalMaxChars {
+		t.Errorf("abovePointerHeadChars = %d, weakFinalMaxChars = %d: the offset bound and the "+
 			"weak-final cap are the same guard and must stay equal",
-			backRefHeadChars, weakFinalMaxChars)
+			abovePointerHeadChars, weakFinalMaxChars)
 	}
 	if weakFinalMaxChars != 120 {
 		t.Errorf("weakFinalMaxChars = %d, want 120: the literal-length cases in this table "+
@@ -291,6 +289,23 @@ func TestIsSummaryCloser(t *testing.T) {
 		// follows is a condensation.
 		{"marker-mid-sentence-is-new-content", "Given the analysis above, the bottom line is that we need a different vendor entirely.", false},
 		{"marker-mid-sentence-in-short", "That is the chain above, and in short supply of alternatives we went with B.", false},
+		// A marker phrase can OPEN a sentence and still be ordinary prose:
+		// "In short supply" is not an announcement of a summary. The delimiter
+		// after the marker is what separates the two.
+		{"marker-word-opens-but-runs-on", "That's the chain above. In short supply of alternatives, we went with B.", false},
+		{"marker-word-opens-but-runs-on-summary", "That's the chain above. In summary meetings we agreed to ship on Tuesday.", false},
+		{"marker-with-a-comma", "That's the chain above. In short, the merger fell through.", true},
+		{"marker-with-a-colon", "That's the chain above. Short answer: no.", true},
+		// No delimiter at all: not matched, so the terminal is kept. Fails
+		// closed, which is today's behaviour rather than a wrong recovery.
+		{"marker-without-a-delimiter", "That's the chain above. In short we went with B.", false},
+		// The delimiter alone is not enough either: mid-sentence, "…, and in
+		// short, we went with B" is a clause continuation, not an announced
+		// summary. This is the case the sentence-opening anchor exists for —
+		// without it a break-check that removed the anchor survived, because
+		// every other mid-sentence case was already rejected for want of a
+		// delimiter.
+		{"marker-mid-sentence-with-a-delimiter", "That is the chain above, and in short, we went with B.", false},
 		{"marker-opening-after-a-colon", "That's the chain above: in short, the merger fell through.", true},
 
 		// A deictic pointer WITHOUT a compression marker is not a summary
@@ -346,7 +361,7 @@ func TestFinalOutput(t *testing.T) {
 	// and long enough (>~92 bytes) that longAnswer would fail the summary bar.
 	bothMatchCloser := "Citations are logged. As I mentioned above, the full detail on the money sources is in my earlier message."
 	// The #1611 pair: a front-loaded analysis that dwarfs its 220-byte closer.
-	analysis := analysis1611()
+	analysis := analysis1611
 	// A deictic pointer followed by a NEW conclusion (no compression marker):
 	// >120 bytes so isWeakFinal cannot claim it, and it must not be treated as
 	// a summary closer either.
@@ -839,7 +854,7 @@ func TestRun_RecoversFrontLoadedAnswerWithCitations(t *testing.T) {
 // compression. The delivered output must be the front-loaded analysis, with no
 // extra model call.
 func TestRun_RecoversFrontLoadedAnswerOverAboveRefCloser(t *testing.T) {
-	analysis := analysis1611()
+	analysis := analysis1611
 	fp := fake.New("fp")
 	fp.Enqueue("test-model",
 		fake.ReplyWith(llm.Response{