fix(glr): certify Python clean-tie election across mixed GSS stacks

admission_switch_a3_arm_noop_confirmation_test.go

@@ -22,21 +22,19 @@ import (
 // on compact-origin trees for that witness -- the retirement precondition
 // follow-up arm-deletion PRs need.
 //
-// RESULT, corrected from the finding: only Apex's witness confirms as a
-// no-op. Perl, Python, and Ada's compat arms still perform real,
-// load-bearing tree reshaping on compact-origin trees even after A3
-// certification lands, on their own tied-election witnesses. The finding's
-// "compact-raw equals compact-tailed on all six witnesses" claim does not
-// reproduce for four of those six (perl push-list; python tuple assignment;
-// both ada aggregates). It reproduces for the fifth, apex class-literal.
+// RESULT, corrected from the finding: Python's tuple-assignment witnesses now
+// confirm as no-op after C-ordered clean-tie selection moves the choice into
+// the producer. Perl and Ada still perform load-bearing reshaping on their
+// tied-election witnesses. Apex has a separate material-election decline.
 //
 // This is consistent with the arm taxonomy (spec.campaign.v7): apex's arm
 // is a fixed derivation relabel that A3's primary-acceptance-derivation
 // certification already subsumes at the scheduler level, so there is
-// nothing left for the arm to do. Perl and Python's arms are
-// scheduler-action arms that perform source-text-scanning list regrouping
-// (ambiguous_function_call_expression / pattern_list-vs-expression_list) --
-// a materially stronger transformation than picking among tied derivations.
+// nothing left for the arm to do. Perl's arm is a scheduler-action arm that
+// performs source-text-scanning list regrouping
+// (ambiguous_function_call_expression). Python's former
+// pattern_list-vs-expression_list rewrite is now an observed no-op on the
+// certified tuple witnesses because the producer makes the C choice.
 // Ada's arms (materialization-owned) relabel one aggregate production into
 // another via a similar structural scan. None of these three
 // transformations are subsumed by the admission-time election flags this
@@ -154,7 +152,7 @@ func TestA3ArmNoOpConfirmationPerlDoesNotConfirm(t *testing.T) {
 	}
 }
 
-func TestA3ArmNoOpConfirmationPythonDoesNotConfirm(t *testing.T) {
+func TestA3ArmNoOpConfirmationPythonConfirms(t *testing.T) {
 	lang := grammars.PythonLanguage()
 	if !lang.CompactPrimaryAcceptanceDerivationCertified || !lang.CompactConvergedReductionSplitDropsCertified {
 		t.Fatal("python did not receive its A3 certification")
@@ -163,7 +161,7 @@ func TestA3ArmNoOpConfirmationPythonDoesNotConfirm(t *testing.T) {
 		{"assignment_bare_tuple", "x, y, z = 1, 2, 3\nxyz = x, y, z\n"},
 		{"assignment_bare_pair", "a = 1\nb = 2\npair = a, b\n"},
 	} {
-		assertA3ArmNoOp(t, "python/"+tt.name, lang, []byte(tt.source), false)
+		assertA3ArmNoOp(t, "python/"+tt.name, lang, []byte(tt.source), true)
 	}
 }
 

cgo_harness/merge_event_census.go

@@ -649,8 +649,10 @@ type mergeCensusTotals struct {
 	CLinkUnionAppended,
 	CLinkUnionRejected uint64
 
-	GoAttempts  uint64
-	GoSuccesses uint64
+	GoAttempts                   uint64
+	GoSuccesses                  uint64
+	MixedRepresentationAttempts  uint64
+	MixedRepresentationSuccesses uint64
 
 	RefuseNoGSSHead      uint64
 	RefuseNoGSSHeadBoth  uint64
@@ -704,6 +706,8 @@ func (t *mergeCensusTotals) add(row mergeCensusRow) {
 
 	t.GoAttempts += row.Go.Attempts
 	t.GoSuccesses += row.Go.Successes
+	t.MixedRepresentationAttempts += row.Go.MixedRepresentationMergeAttempts
+	t.MixedRepresentationSuccesses += row.Go.MixedRepresentationMergeSuccesses
 
 	t.RefuseNoGSSHead += row.Go.RefuseNoGSSHead
 	t.RefuseNoGSSHeadBoth += row.Go.RefuseNoGSSHeadBoth

cgo_harness/merge_event_census_test.go

@@ -40,6 +40,8 @@ func TestMergeCensusTotalsAggregatesPhysicalHeadMergeTelemetry(t *testing.T) {
 			CompactPhysicalHeadMergeAttempts:   3,
 			CompactPhysicalHeadMergeSuccesses:  2,
 			CompactPhysicalHeadMergeInputLinks: 5,
+			MixedRepresentationMergeAttempts:   4,
+			MixedRepresentationMergeSuccesses:  1,
 		},
 	})
 	totals.add(mergeCensusRow{
@@ -48,12 +50,16 @@ func TestMergeCensusTotalsAggregatesPhysicalHeadMergeTelemetry(t *testing.T) {
 			CompactPhysicalHeadMergeAttempts:   7,
 			CompactPhysicalHeadMergeSuccesses:  4,
 			CompactPhysicalHeadMergeInputLinks: 9,
+			MixedRepresentationMergeAttempts:   6,
+			MixedRepresentationMergeSuccesses:  3,
 		},
 	})
 	if totals.CompactPhysicalAttempts != 10 || totals.CompactPhysicalSuccesses != 6 ||
-		totals.CompactPhysicalInputLinks != 14 {
-		t.Fatalf("physical merge totals=%d/%d/%d, want 10/6/14",
+		totals.CompactPhysicalInputLinks != 14 || totals.MixedRepresentationAttempts != 10 ||
+		totals.MixedRepresentationSuccesses != 4 {
+		t.Fatalf("merge totals physical=%d/%d/%d mixed=%d/%d, want physical=10/6/14 mixed=10/4",
 			totals.CompactPhysicalAttempts, totals.CompactPhysicalSuccesses, totals.CompactPhysicalInputLinks,
+			totals.MixedRepresentationAttempts, totals.MixedRepresentationSuccesses,
 		)
 	}
 }
@@ -121,7 +127,7 @@ var mergeCensusBaselineConstructed = map[string]struct {
 	// Clean-suffix reset removes four redundant Kotlin merges. Exact C tree
 	// parity remains pinned by TestKotlinRecoverySuffixSourcesMatchC.
 	"kotlin": {Sources: 13, CMergeSuccesses: 54, GoSuccesses: 8, RefuseNoGSSHead: 2, RefuseScoreOrShifted: 0, RefuseDistinctShapes: 0, LinkPayloadShallowWouldAccept: 8, SourcesWhereGoOverMerges: 0, SourcesWhereCMergesAndGoDoesNot: 3},
-	"python": {Sources: 26, CMergeSuccesses: 2, GoSuccesses: 0, RefuseNoGSSHead: 9, RefuseScoreOrShifted: 0, RefuseDistinctShapes: 0, LinkPayloadShallowWouldAccept: 0, SourcesWhereGoOverMerges: 0, SourcesWhereCMergesAndGoDoesNot: 2},
+	"python": {Sources: 30, CMergeSuccesses: 2, GoSuccesses: 0, RefuseNoGSSHead: 9, RefuseScoreOrShifted: 0, RefuseDistinctShapes: 0, LinkPayloadShallowWouldAccept: 0, SourcesWhereGoOverMerges: 0, SourcesWhereCMergesAndGoDoesNot: 2},
 }
 
 // The M0 pinned aggregate over the five A3 sweep corpora's constructed
@@ -133,8 +139,8 @@ const (
 	mergeCensusBaselineCMerges  uint64 = 191
 	mergeCensusBaselineGoMerges uint64 = 11
 	// mergeCensusBaselineSources is the constructed-source denominator, the
-	// same 104 sources D0 measures.
-	mergeCensusBaselineSources = 104
+	// same 108 sources D0 measures.
+	mergeCensusBaselineSources = 108
 )
 
 // TestMergeEventCensusBaseline publishes the M0 baseline: how many merges the
@@ -271,9 +277,10 @@ func TestMergeEventCensusBaseline(t *testing.T) {
 
 func mergeCensusFormatTotals(label string, t *mergeCensusTotals) string {
 	return fmt.Sprintf(
-		"%-22s sources=%3d M_c=%6d M_p=%6d ratio=%-8s c-attempts=%7d go-attempts=%7d over-merge-sources=%d c-merges-go-does-not=%d | refusals: %s | tier2: %s | compact: accepted=%d union-attempts=%d union-appends=%d physical-attempts=%d physical-successes=%d physical-input-links=%d",
+		"%-22s sources=%3d M_c=%6d M_p=%6d ratio=%-8s c-attempts=%7d go-attempts=%7d over-merge-sources=%d c-merges-go-does-not=%d | mixed=%d/%d | refusals: %s | tier2: %s | compact: accepted=%d union-attempts=%d union-appends=%d physical-attempts=%d physical-successes=%d physical-input-links=%d",
 		label, t.Sources, t.CMergeSuccesses, t.GoSuccesses, t.ratioText(),
 		t.CMergeAttempts, t.GoAttempts, t.SourcesWhereGoOverMerges, t.SourcesWhereCMergesAndGoDoesNot,
+		t.MixedRepresentationAttempts, t.MixedRepresentationSuccesses,
 		t.refusalLine(), t.linkPayloadLine(),
 		t.CompactAccepted, t.CompactUnionAttempt, t.CompactUnionAppend,
 		t.CompactPhysicalAttempts, t.CompactPhysicalSuccesses, t.CompactPhysicalInputLinks,

cgo_harness/python_a3_certification_sweep_test.go

@@ -14,10 +14,10 @@ import (
 // certification-workstream (spec.campaign.v7, finding
 // tied-election-family-compact-retirement) full-corpus verification receipt
 // for Python. Python already shipped CompactConvergedReductionSplitDropsCertified;
-// this sweep gates the added CompactPrimaryAcceptanceDerivationCertified
-// grant (grammars/runtime_profiles.go) on zero unadjudicated compact-vs-C
-// divergence across the real corpus plus the tied-election and known-gap
-// tuple/f-string witnesses (python_scheduler_action_local_parity_test.go).
+// this sweep gates the added compact acceptance grants
+// (grammars/runtime_profiles.go) on zero unadjudicated compact-vs-C divergence
+// across the real corpus plus the tied-election tuple/f-string witnesses
+// (python_scheduler_action_local_parity_test.go).
 func TestPythonA3CompactCertificationFullCorpusSweep(t *testing.T) {
 	lang := grammars.PythonLanguage()
 	if !lang.CompactPrimaryAcceptanceDerivationCertified {
@@ -63,30 +63,17 @@ func TestPythonA3CompactCertificationFullCorpusSweep(t *testing.T) {
 // at all. The stale-entry ratchet in a3ReportSweep enforces this: it fails
 // the sweep if a remaining entry stops matching a live divergence.
 //
-// The two f-string entries are family D (a first-class declared
-// pattern_list/expression_list ambiguity; Go's reduceForkWindowPreference
-// disagrees with C's ts_parser__select_tree on which side to keep). Not
-// tied elections, not this gate's scope; repair lanes are tracked
-// separately.
-var pythonA3KnownDivergences = []a3KnownDivergence{
-	{
-		Witness:   "fstring_interpolation_bare_tuple",
-		FirstPath: "/module/assignment[2]/string[2]/interpolation[1]/pattern_list[1]",
-		GoValue:   "pattern_list", CValue: "expression_list", Family: "D",
-	},
-	{
-		Witness:   "fstring_interpolation_splat",
-		FirstPath: "/module/assignment[1]/string[2]/interpolation[1]/pattern_list[1]",
-		GoValue:   "pattern_list", CValue: "expression_list", Family: "D",
-	},
-}
+// The two former f-string entries were family D (a first-class declared
+// pattern_list/expression_list ambiguity). C-ordered clean-tie selection now
+// emits expression_list for the exact Python artifact, so these entries are
+// retired from the active known-divergence list. The historical values remain
+// in docs/root-normalization-retirement.md and the blocker receipt.
+var pythonA3KnownDivergences = []a3KnownDivergence{}
 
-// pythonA3AdversarialSources gathers Python's tied-election witness (the
-// bare-tuple assignment right-hand side) plus its known-gap and neutral
-// control sources
-// (python_scheduler_action_local_parity_test.go), all already vetted as
-// conflict-heavy shapes for this grammar's pattern_list/expression_list
-// election.
+// pythonA3AdversarialSources gathers Python's tied-election witnesses, the
+// former f-string blocker shapes, and neutral controls
+// (python_scheduler_action_local_parity_test.go). These sources exercise
+// conflict-heavy pattern_list/expression_list choices for this grammar.
 func pythonA3AdversarialSources() []a3CertificationSweepSource {
 	return []a3CertificationSweepSource{
 		{Name: "assignment_bare_tuple_real_corpus_witness", Source: []byte("x, y, z = 1, 2, 3\nxyz = x, y, z\n")},
@@ -109,10 +96,14 @@ func pythonA3AdversarialSources() []a3CertificationSweepSource {
 		{Name: "for_target_tuple_negative_control", Source: []byte("pairs = [(1, 2)]\nfor a, b in pairs:\n    pass\n")},
 		{Name: "chained_assignment_lhs_negative_control", Source: []byte("a, b = c, d = 1, 2\n")},
 		{Name: "del_tuple_negative_control", Source: []byte("a = 1\nb = 2\ndel a, b\n")},
+		{Name: "with_multiple_as_targets", Source: []byte("with context() as a, other() as b:\n    pass\n")},
+		{Name: "except_multiple_as_targets", Source: []byte("try:\n    pass\nexcept E as a, F as b:\n    pass\n")},
 		{Name: "walrus_in_comprehension", Source: []byte("data = [1, 2, 3]\nresult = [y for x in data if (y := x * 2) > 2]\n")},
 		{Name: "decorated_async_def", Source: []byte("import functools\n\n@functools.wraps\nasync def f(x, *, y=1, **kw):\n    return x, y\n")},
 		{Name: "star_expr_unpack", Source: []byte("first, *rest = [1, 2, 3]\n")},
 		{Name: "lambda_tuple_return", Source: []byte("f = lambda x, y: (x, y)\n")},
+		{Name: "fstring_call_arguments", Source: []byte("s = f\"{foo(a, b)}\"\n")},
+		{Name: "fstring_parenthesized_tuple", Source: []byte("s = f\"{(x, y)}\"\n")},
 		{Name: "nested_fstring_conversion", Source: []byte("name = \"world\"\ns = f\"{name!r:>{10}}\"\n")},
 	}
 }