fix(trace): an action names the generator that produced it

The setup exclusion landed for the model arm only, because only a model
pick stamped a source. A seeded run returned setup's action through the
same entry with no marker, so its denominator still counted the login
while the model arm's did not, and the two are compared.

serializeAction names setup and seeded on the wire, so both arms are
counted by one rule. An already-recorded trace names nothing and keeps
exactly the count it was reported with; unattributed_actions counts those
steps so the old denominator cannot pass as the new one. TraceVersion is
deliberately unbumped: oracle-reduction refuses a differing version, and
a bump would make all 169 recorded runs unreplayable.

cmd/internal-tools/campaign/summary_test.go

@@ -40,13 +40,20 @@ func setupStep(index int) trace.Step {
 		Kind:     "InputText",
 		Selector: "testTag:LoginScreen > testTag:LoginEmail",
 		Text:     "[email protected]",
+		Source:   trace.ActionSourceSetup,
 	}
 	return step
 }
 
+func seededStep(index int) trace.Step {
+	step := actingStep(index)
+	step.NextAction.Source = trace.ActionSourceSeeded
+	return step
+}
+
 func modelStep(index int) trace.Step {
 	step := actingStep(index)
-	step.NextAction.Source = "llm"
+	step.NextAction.Source = trace.ActionSourceModel
 	return step
 }
 
@@ -189,7 +196,7 @@ func TestSummarizeRun_ModelRunWithoutSetupCountsEveryDispatchedStep(t *testing.T
 	}
 }
 
-func TestSummarizeRun_SeededRunCountsSetupBecauseItsTraceCannotNameIt(t *testing.T) {
+func TestSummarizeRun_SeededRunLeavesTheSetupsLoginOutOfTheActionCount(t *testing.T) {
 	seedDirectory := t.TempDir()
 	writeRunDirectoryWithMeta(t, seedDirectory, "20260812-090000",
 		trace.Meta{Seed: 11, Platform: "web", Arm: "seeded-baseline", Generator: "seeded"},
@@ -197,17 +204,73 @@ func TestSummarizeRun_SeededRunCountsSetupBecauseItsTraceCannotNameIt(t *testing
 			setupStep(1),
 			setupStep(2),
 			setupStep(3),
-			actingStep(4),
-			actingStep(5),
+			seededStep(4),
+			seededStep(5),
 		})
 
 	_, summary, err := summarizeRun(seedDirectory)
 	if err != nil {
 		t.Fatal(err)
 	}
-	if summary.Actions != 5 {
-		t.Errorf("actions: got %d, want 5: the seeded picker stamps no source, so excluding "+
-			"unstamped steps would count its whole run as setup", summary.Actions)
+	if summary.Actions != 2 {
+		t.Errorf("actions: got %d, want 2 (three login steps were setup's), which is the same "+
+			"rule the model arm is counted by", summary.Actions)
+	}
+	if summary.UnattributedActions != 0 {
+		t.Errorf("unattributed actions: got %d, want 0: every step named its source",
+			summary.UnattributedActions)
+	}
+}
+
+func TestSummarizeRun_SeededRunWithoutSetupCountsEveryDispatchedStep(t *testing.T) {
+	seedDirectory := t.TempDir()
+	writeRunDirectoryWithMeta(t, seedDirectory, "20260812-090000",
+		trace.Meta{Seed: 11, Platform: "web", Arm: "seeded-baseline", Generator: "seeded"},
+		[]trace.Step{seededStep(1), seededStep(2), seededStep(3), seededStep(4)})
+
+	_, summary, err := summarizeRun(seedDirectory)
+	if err != nil {
+		t.Fatal(err)
+	}
+	if summary.Actions != 4 {
+		t.Errorf("actions: got %d, want 4", summary.Actions)
+	}
+}
+
+// Traces recorded before actions named their source cannot be re-attributed
+// after the fact, so each arm keeps the count it was already reported with: the
+// seeded arm counts every dispatched step, the model arm counts only what the
+// model stamped. UnattributedActions is how such a run says so rather than
+// passing its old denominator off as a setup-excluding one.
+func TestSummarizeRun_TraceWithoutSourcesKeepsTheCountItWasReportedWith(t *testing.T) {
+	for _, testCase := range []struct {
+		generator           string
+		actions             int
+		unattributedActions int
+	}{
+		{generator: "seeded", actions: 5, unattributedActions: 5},
+		{generator: "llm", actions: 0, unattributedActions: 5},
+	} {
+		t.Run(testCase.generator, func(t *testing.T) {
+			seedDirectory := t.TempDir()
+			writeRunDirectoryWithMeta(t, seedDirectory, "20260812-090000",
+				trace.Meta{Seed: 11, Platform: "web", Generator: testCase.generator},
+				[]trace.Step{
+					actingStep(1), actingStep(2), actingStep(3), actingStep(4), actingStep(5),
+				})
+
+			_, summary, err := summarizeRun(seedDirectory)
+			if err != nil {
+				t.Fatal(err)
+			}
+			if summary.Actions != testCase.actions {
+				t.Errorf("actions: got %d, want %d", summary.Actions, testCase.actions)
+			}
+			if summary.UnattributedActions != testCase.unattributedActions {
+				t.Errorf("unattributed actions: got %d, want %d",
+					summary.UnattributedActions, testCase.unattributedActions)
+			}
+		})
 	}
 }