router: add provenance tests for ActionResolutionMethod

Pin each path: grammar_fixed, grammar_matcher, extractor_raw,
extractor_llm_text, fallback_matcher. Verify unresolved has empty
ResolvedBy. Verify fn/args remain byte-for-byte identical.

internal/router/actioncandidate_test.go

@@ -352,3 +352,181 @@ func TestValidateActionCandidate_IssuesPopulatedOnInvalid(t *testing.T) {
 		t.Error("invalid result has no issues")
 	}
 }
+
+// --- ResolutionMethod provenance tests ---
+
+// TestResolveActionCandidate_GrammarFixed pins that a stage-0 grammar that
+// hardcodes fn (praxis/task-status) carries grammar_fixed provenance.
+func TestResolveActionCandidate_GrammarFixed(t *testing.T) {
+	dec := Decision{
+		Intent: IntentAct,
+		Slots: Slots{
+			Fn: "resolve_item", HasFn: true,
+			ResolvedBy: ActionResolutionGrammarFixed,
+		},
+	}
+	c := ResolveActionCandidate(dec, nil)
+	if !c.ActionResolved() {
+		t.Fatal("expected resolved candidate")
+	}
+	if c.ResolvedBy != ActionResolutionGrammarFixed {
+		t.Errorf("ResolvedBy = %q, want grammar_fixed", c.ResolvedBy)
+	}
+	if c.Fn != "resolve_item" {
+		t.Errorf("Fn = %q, want resolve_item", c.Fn)
+	}
+}
+
+// TestResolveActionCandidate_GrammarMatcher pins that a stage-0 grammar that
+// invokes the ActMatcher (wakeword-act) carries grammar_matcher provenance.
+func TestResolveActionCandidate_GrammarMatcher(t *testing.T) {
+	dec := Decision{
+		Intent: IntentAct,
+		Slots: Slots{
+			Fn: "restart", Args: []string{"nginx"}, HasFn: true,
+			ResolvedBy: ActionResolutionGrammarMatcher,
+		},
+	}
+	c := ResolveActionCandidate(dec, nil)
+	if !c.ActionResolved() {
+		t.Fatal("expected resolved candidate")
+	}
+	if c.ResolvedBy != ActionResolutionGrammarMatcher {
+		t.Errorf("ResolvedBy = %q, want grammar_matcher", c.ResolvedBy)
+	}
+}
+
+// TestResolveActionCandidate_ExtractorRaw pins that a classifier/heads-routed
+// act whose extractor matched carries extractor_raw provenance.
+func TestResolveActionCandidate_ExtractorRaw(t *testing.T) {
+	dec := Decision{
+		Intent: IntentAct,
+		Slots: Slots{
+			Fn: "restart", HasFn: true,
+			ResolvedBy: ActionResolutionExtractorRaw,
+		},
+		Producer: RouteProducerClassifier,
+	}
+	c := ResolveActionCandidate(dec, nil)
+	if !c.ActionResolved() {
+		t.Fatal("expected resolved candidate")
+	}
+	if c.ResolvedBy != ActionResolutionExtractorRaw {
+		t.Errorf("ResolvedBy = %q, want extractor_raw", c.ResolvedBy)
+	}
+	if c.Producer != RouteProducerClassifier {
+		t.Errorf("Producer = %q, want classifier", c.Producer)
+	}
+}
+
+// TestResolveActionCandidate_ExtractorLLMText pins that an LLM-routed act
+// whose function was resolved from the LLM's cleaned text carries
+// extractor_llm_text provenance.
+func TestResolveActionCandidate_ExtractorLLMText(t *testing.T) {
+	dec := Decision{
+		Intent: IntentAct,
+		Slots: Slots{
+			Fn: "restart", HasFn: true,
+			ResolvedBy: ActionResolutionExtractorLLMText,
+		},
+		Producer: RouteProducerLLM,
+	}
+	c := ResolveActionCandidate(dec, nil)
+	if !c.ActionResolved() {
+		t.Fatal("expected resolved candidate")
+	}
+	if c.ResolvedBy != ActionResolutionExtractorLLMText {
+		t.Errorf("ResolvedBy = %q, want extractor_llm_text", c.ResolvedBy)
+	}
+	if c.Producer != RouteProducerLLM {
+		t.Errorf("Producer = %q, want llm", c.Producer)
+	}
+}
+
+// TestResolveActionCandidate_FallbackMatcher pins that a matcher fallback
+// carry fallback_matcher provenance.
+func TestResolveActionCandidate_FallbackMatcher(t *testing.T) {
+	m := DefaultActMatcher{Fns: []string{"restart", "stop"}}
+	dec := Decision{
+		Intent: IntentAct,
+		Slots:  Slots{Text: "restart nginx"},
+	}
+	c := ResolveActionCandidate(dec, m)
+	if !c.ActionResolved() {
+		t.Fatal("expected resolved candidate")
+	}
+	if c.ResolvedBy != ActionResolutionFallbackMatcher {
+		t.Errorf("ResolvedBy = %q, want fallback_matcher", c.ResolvedBy)
+	}
+	if c.Source != ActionSourceMatcher {
+		t.Errorf("Source = %q, want matcher", c.Source)
+	}
+}
+
+// TestResolveActionCandidate_UnresolvedNoFalseMethod pins that an unresolved
+// candidate (matcher miss) has empty ResolvedBy.
+func TestResolveActionCandidate_UnresolvedNoFalseMethod(t *testing.T) {
+	m := DefaultActMatcher{Fns: []string{"restart", "stop"}}
+	dec := Decision{
+		Intent: IntentAct,
+		Slots:  Slots{Text: "deploy the thing"},
+	}
+	c := ResolveActionCandidate(dec, m)
+	if c.ActionResolved() {
+		t.Fatal("expected unresolved candidate")
+	}
+	if c.ResolvedBy != "" {
+		t.Errorf("ResolvedBy = %q, want empty for unresolved", c.ResolvedBy)
+	}
+}
+
+// TestResolveActionCandidate_PropagatesResolvedBy pins that ResolvedBy
+// travels from Slots through to ActionCandidate for every route-sourced case.
+func TestResolveActionCandidate_PropagatesResolvedBy(t *testing.T) {
+	methods := []ActionResolutionMethod{
+		ActionResolutionGrammarFixed,
+		ActionResolutionGrammarMatcher,
+		ActionResolutionExtractorRaw,
+		ActionResolutionExtractorLLMText,
+	}
+	for _, m := range methods {
+		t.Run(string(m), func(t *testing.T) {
+			dec := Decision{
+				Intent: IntentAct,
+				Slots:  Slots{Fn: "restart", HasFn: true, ResolvedBy: m},
+			}
+			c := ResolveActionCandidate(dec, nil)
+			if c.ResolvedBy != m {
+				t.Errorf("ResolvedBy = %q, want %q", c.ResolvedBy, m)
+			}
+		})
+	}
+}
+
+// TestResolveActionCandidate_FnArgsIdentical pins that adding ResolvedBy
+// does not change the selected fn or args for any path.
+func TestResolveActionCandidate_FnArgsIdentical(t *testing.T) {
+	// Route-sourced.
+	dec := Decision{
+		Intent: IntentAct,
+		Slots: Slots{
+			Fn: "restart", Args: []string{"nginx"}, HasFn: true,
+			ResolvedBy: ActionResolutionGrammarMatcher,
+		},
+	}
+	c := ResolveActionCandidate(dec, nil)
+	if c.Fn != "restart" || len(c.Args) != 1 || c.Args[0] != "nginx" {
+		t.Errorf("route fn/args changed: Fn=%q Args=%v", c.Fn, c.Args)
+	}
+
+	// Matcher-sourced.
+	m := DefaultActMatcher{Fns: []string{"restart"}}
+	dec2 := Decision{
+		Intent: IntentAct,
+		Slots:  Slots{Text: "restart nginx"},
+	}
+	c2 := ResolveActionCandidate(dec2, m)
+	if c2.Fn != "restart" || len(c2.Args) != 1 || c2.Args[0] != "nginx" {
+		t.Errorf("matcher fn/args changed: Fn=%q Args=%v", c2.Fn, c2.Args)
+	}
+}