Reuse alias tree for discovery and help

docs/roadmap/audit/catalog.md

@@ -1,6 +1,6 @@
 # Consolidated audit catalog
 
-Status: **11 distinct open findings: 11 P3**, consolidated from 30
+Status: **9 distinct open findings: 9 P3**, consolidated from 30
 numbered entries in seven audit documents. Reviewed audit state:
 `db732e3a1de55c844f77870e1c6db683c2685d5d`.
 
@@ -296,6 +296,10 @@ selected routing and discovery semantics.
 
 ## F14 — P3: Discovery-context preparation repeatedly rebuilds shared prefixes
 
+**Complete.** Distinct trie prefixes are enumerated and classified once;
+focused discovery and resolver tests pass, and traversal was reviewed for
+elimination of repeated per-declaration prefix construction.
+
 R alias sources sharing a depth-D proper prefix cause Θ(RD²) copying and key
 construction before result deduplication, with repeated classification as well.
 The source declarations contain only Θ(RD) tokens.
@@ -313,12 +317,16 @@ Reuse the tree's routing-snapshot lifetime; do not introduce a parallel index or
 a cross-invocation result cache. The repeated preparation and help-time scan
 remain distinct findings. The [joint analysis](remediation-analysis.md#f14f15--joint-source-prefix-design)
 records the accepted design. The performance-testing decision under F13 applies
-to both; implementation remains pending.
+to both.
 
 **Original:** [02-efficiency E3](02-efficiency.md#e3--p3-discovery-context-preparation-rebuilds-shared-prefixes-repeatedly).
 
 ## F15 — P3: Alias help scans the entire source catalog for each intermediate route
 
+**Complete.** Help queries strict descendants from each resolution path instead
+of scanning the complete catalog. Focused alias/help tests pass, and the tree
+traversal was reviewed for the removal of unrelated source scans.
+
 Help discovery examines all A alias sources at each of P rewrite paths, doing PA
 examinations and repeated copies even when there are no descendants. A valid
 single-token alias chain produces Θ(A²) work to discover an empty alias section

docs/roadmap/implementation.md

@@ -1,6 +1,6 @@
 # Audit remediation implementation plan
 
-Status: in progress; Stages 1–15 complete.
+Status: in progress; Stages 1–16 complete.
 
 Baseline: `d492c7747175c01a53261206c2b4356e53453621`. Before this sprint,
 intervening changes recorded decisions and retired the completed older
@@ -527,6 +527,12 @@ Complete when repeated suffix traversal is removed without routing changes.
 
 ## Stage 16 — Reuse the resolver tree for prefix discovery and help
 
+**Complete.** Discovery classifies each eligible trie prefix once (F14), and
+help visits only strict descendants for each resolution path (F15). Source
+review confirms both changes use the existing resolver tree; focused alias,
+discovery, help and resolver tests pass offline with Go 1.27.0 and
+`-mod=readonly`, including returned-path ownership and exact aliases with children.
+
 Findings: F14 and F15, one coordinated change. Sources:
 `internal/alias/resolver.go`, `flag_aliases.go`, and `help_view.go`.
 

flag_aliases.go

@@ -66,6 +66,7 @@ func (spelling capturedFlagSpelling) token() string {
 
 func compileFlagAliases(rules []RoutingRule, roots map[string]*canonicalNode, aliases interface {
 	Resolve(commandpath.Path) commandpath.Path
+	ProperSourcePrefixes() []commandpath.Path
 }) (map[string]resolvedFlagAliases, map[string]resolvedFlagAliases, error) {
 	canonicalNodes := indexCanonicalNodes(roots)
 	global := make(map[string]flagAliasMapping)
@@ -170,6 +171,7 @@ func canonicalFlagSpellings(command Command) map[string]capturedFlagSpelling {
 
 func discoverFlagContexts(rules []RoutingRule, roots map[string]*canonicalNode, aliases interface {
 	Resolve(commandpath.Path) commandpath.Path
+	ProperSourcePrefixes() []commandpath.Path
 }, canonicalNodes map[string]*canonicalNode) map[string]flagAliasContext {
 	commandSources := make(map[string]struct{})
 	prefixes := make(map[string]commandpath.Path)
@@ -178,12 +180,7 @@ func discoverFlagContexts(rules []RoutingRule, roots map[string]*canonicalNode,
 			commandSources[rule.record.sourcePath.Key()] = struct{}{}
 		}
 	}
-	for _, rule := range rules {
+	for _, prefix := range aliases.ProperSourcePrefixes() {
-		if rule.record.kind != commandAliasRule {
-			continue
-		}
-		for length := 1; length < len(rule.record.sourcePath); length++ {
-			prefix := rule.record.sourcePath[:length].Clone()
 		key := prefix.Key()
 		if canonicalNodes[key] != nil {
 			continue
@@ -198,7 +195,6 @@ func discoverFlagContexts(rules []RoutingRule, roots map[string]*canonicalNode,
 		}
 		prefixes[key] = prefix
 	}
-	}
 	contexts := make(map[string]flagAliasContext, len(prefixes))
 	for key, path := range prefixes {
 		contexts[key] = flagAliasContext{path: path, canonical: helpFlagSpellings(), discovery: true}

help_view.go

@@ -36,11 +36,8 @@ func routeHelpAliases(snapshot *routingSnapshot, route routeResult) []commandmet
 	}
 	bySource := make(map[string]commandmeta.CommandAlias)
 	for _, prefix := range snapshot.aliases.ResolutionPaths(route.enteredPath) {
-		for _, alias := range snapshot.commandAliases {
+		for _, alias := range snapshot.aliases.Descendants(prefix) {
-			source := commandpath.FromTokens(alias.Source)
+			source := alias.Source
-			if len(source) <= len(prefix) || !source.HasPrefix(prefix) {
-				continue
-			}
 			suffix := source[len(prefix):]
 			entered := append(route.enteredPath.Clone(), suffix...)
 			target := snapshot.aliases.Resolve(entered)

internal/alias/resolver.go

@@ -182,3 +182,50 @@ func (resolver *Resolver) ResolveWithProvenance(path commandpath.Path) (commandp
 		origins = nextOrigins
 	}
 }
+
+// ProperSourcePrefixes returns distinct nonempty proper prefixes of source paths.
+// Returned paths are owned by the caller.
+func (resolver *Resolver) ProperSourcePrefixes() []commandpath.Path {
+	if resolver == nil {
+		return nil
+	}
+	var paths []commandpath.Path
+	for index := 1; index < len(resolver.trie); index++ {
+		node := &resolver.trie[index]
+		if len(node.children) != 0 {
+			paths = append(paths, node.path.Clone())
+		}
+	}
+	return paths
+}
+
+// Descendants returns owned mappings whose sources are strictly below prefix.
+func (resolver *Resolver) Descendants(prefix commandpath.Path) []Mapping {
+	if resolver == nil {
+		return nil
+	}
+	index := 0
+	for _, component := range prefix {
+		next, ok := resolver.trie[index].children[component]
+		if !ok {
+			return nil
+		}
+		index = next
+	}
+	var mappings []Mapping
+	var visit func(int)
+	visit = func(index int) {
+		node := &resolver.trie[index]
+		if node.mapping >= 0 {
+			mapping := resolver.mappings[node.mapping]
+			mappings = append(mappings, Mapping{Source: mapping.Source.Clone(), Target: mapping.Target.Clone()})
+		}
+		for _, child := range node.children {
+			visit(child)
+		}
+	}
+	for _, child := range resolver.trie[index].children {
+		visit(child)
+	}
+	return mappings
+}

internal/alias/resolver_test.go

@@ -314,3 +314,34 @@ func (machine *Machine) classify(token string) symbol {
 	}
 	return symbol{kind: otherSymbol}
 }
+
+func TestResolverSourcePrefixesAndDescendantsAreOwned(t *testing.T) {
+	resolver, err := NewResolver([]Mapping{
+		{Source: commandpath.Path{"a"}, Target: commandpath.Path{"root"}},
+		{Source: commandpath.Path{"a", "b", "one"}, Target: commandpath.Path{"root", "one"}},
+		{Source: commandpath.Path{"a", "b", "two"}, Target: commandpath.Path{"root", "two"}},
+		{Source: commandpath.Path{"other"}, Target: commandpath.Path{"root"}},
+	})
+	if err != nil {
+		t.Fatal(err)
+	}
+	prefixes := resolver.ProperSourcePrefixes()
+	if len(prefixes) != 2 || !prefixes[0].Equal(commandpath.Path{"a"}) || !prefixes[1].Equal(commandpath.Path{"a", "b"}) {
+		t.Fatalf("prefixes = %#v", prefixes)
+	}
+	prefixes[0][0] = "mutated"
+	descendants := resolver.Descendants(commandpath.Path{"a"})
+	if len(descendants) != 2 {
+		t.Fatalf("descendants = %#v", descendants)
+	}
+	for _, mapping := range descendants {
+		if len(mapping.Source) != 3 || mapping.Source[0] != "a" {
+			t.Fatalf("mapping = %#v", mapping)
+		}
+	}
+	descendants[0].Source[0] = "mutated"
+	descendants[0].Target[0] = "mutated"
+	if !resolver.Resolve(commandpath.Path{"a", "b", "one"}).Equal(commandpath.Path{"root", "one"}) || len(resolver.Descendants(commandpath.Path{"missing"})) != 0 {
+		t.Fatal("resolver was mutated or missing branch returned mappings")
+	}
+}