Collapse dead parser rung and drop write-only Deps.Parser field

Two parser-plumbing test seams flagged by the interface audit:

- The commentParserWithLanguage rung in parseForBuild only matched a
  test parser that implemented ParseWithComments but not the richer
  ParseWithCommentsAndMetadata; production parsers (*treesitter.Walker)
  always match the metadata rung. Upgrade that test parser to the full
  metadata contract and delete the middle rung and its interface.
- Deps.Parser had no production reader (graphService builds from
  Deps.Walkers); only a test built an incremental syncer from it. Point
  that test at Deps.Walkers[".go"] and remove the field and its wiring.

No production behavior change: Walker already took the metadata path and
Deps.Parser was never read outside tests.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

Author: tae2089

internal/mcp/deps.go

@@ -150,7 +150,6 @@ type PostprocessPolicy interface {
 type Deps struct {
 	Store            store.GraphStore
 	DB               *gorm.DB
-	Parser           Parser
 	Walkers          map[string]Parser
 	SearchBackend    storesearch.Backend
 	ImpactAnalyzer   ImpactAnalyzer

internal/mcp/e2e_test.go

@@ -54,7 +54,6 @@ func setupE2EDeps(t *testing.T) *Deps {
 	return &Deps{
 		Store:          st,
 		DB:             db,
-		Parser:         goParser,
 		Walkers:        map[string]Parser{".go": goParser},
 		SearchBackend:  sb,
 		ImpactAnalyzer: impact.New(st),
@@ -243,7 +242,7 @@ func TestE2E_IncrementalReparse(t *testing.T) {
 	deps := setupE2EDeps(t)
 	ctx := context.Background()
 
-	syncer := incremental.New(deps.Store, deps.Parser)
+	syncer := incremental.New(deps.Store, deps.Walkers[".go"])
 
 	// Step 1: Initial parse
 	originalCode := `package calc

internal/mcp/testhelpers_test.go

@@ -126,6 +126,11 @@ func (p *commentAwareGoParser) ParseWithComments(ctx context.Context, filePath s
 	return nodes, edges, comments, nil
 }
 
+func (p *commentAwareGoParser) ParseWithCommentsAndMetadata(ctx context.Context, filePath string, content []byte) ([]model.Node, []model.Edge, []treesitter.CommentBlock, treesitter.ParseMetadata, error) {
+	nodes, edges, comments, err := p.ParseWithComments(ctx, filePath, content)
+	return nodes, edges, comments, treesitter.ParseMetadata{}, err
+}
+
 func (p *commentAwareGoParser) Language() string {
 	return "go"
 }
@@ -159,7 +164,6 @@ func setupTestDeps(t *testing.T) *Deps {
 	return &Deps{
 		Store:          st,
 		DB:             db,
-		Parser:         goParser,
 		Walkers:        map[string]Parser{".go": goParser},
 		SearchBackend:  sb,
 		ImpactAnalyzer: impact.New(st),
@@ -203,7 +207,6 @@ func setupTestDepsMinimal(t *testing.T) *Deps {
 	return &Deps{
 		Store:          st,
 		DB:             db,
-		Parser:         goParser,
 		Walkers:        map[string]Parser{".go": goParser},
 		SearchBackend:  sb,
 		ImpactAnalyzer: impact.New(st),
@@ -239,7 +242,6 @@ func setupGraphOnlyTestDeps(t *testing.T) *Deps {
 	return &Deps{
 		Store:          st,
 		DB:             db,
-		Parser:         goParser,
 		Walkers:        map[string]Parser{".go": goParser},
 		ImpactAnalyzer: impact.New(st),
 		FlowTracer:     flows.New(st),
@@ -373,7 +375,6 @@ func setupTestDepsWithComments(t *testing.T) *Deps {
 	t.Helper()
 	deps := setupTestDeps(t)
 	goParser := &commentAwareGoParser{}
-	deps.Parser = goParser
 	deps.Walkers = map[string]Parser{".go": goParser}
 	return deps
 }

internal/mcpruntime/runtime.go

@@ -87,7 +87,6 @@ func New(rt *core.Runtime, opts Options) (*Instance, error) {
 	mcpDeps := &mcp.Deps{
 		Store:               rt.Store,
 		DB:                  rt.DB,
-		Parser:              rt.Walkers[".go"],
 		Walkers:             mcpWalkers,
 		SearchBackend:       rt.SearchBackend,
 		ImpactAnalyzer:      impact.New(rt.Store),

internal/service/fileio.go

@@ -56,10 +56,6 @@ func parseForBuild(ctx context.Context, parser Parser, relPath string, content [
 		nodes, edges, comments, meta, err := mp.ParseWithCommentsAndMetadata(ctx, relPath, content)
 		return nodes, edges, comments, meta, mp.Language(), err
 	}
-	if cp, ok := parser.(commentParserWithLanguage); ok {
-		nodes, edges, comments, err := cp.ParseWithComments(ctx, relPath, content)
-		return nodes, edges, comments, treesitter.ParseMetadata{}, cp.Language(), err
-	}
 	nodes, edges, err := parser.ParseWithContext(ctx, relPath, content)
 	return nodes, edges, nil, treesitter.ParseMetadata{}, "", err
 }

internal/service/indexer.go

@@ -44,14 +44,6 @@ type Parser interface {
 	ParseWithContext(ctx context.Context, filePath string, content []byte) ([]model.Node, []model.Edge, error)
 }
 
-// commentParserWithLanguage is the optional contract a Parser may satisfy to expose comment blocks plus its source language.
-// @intent let the build pipeline collect docstring/comment blocks alongside nodes and edges when the parser supports it.
-type commentParserWithLanguage interface {
-	Parser
-	ParseWithComments(ctx context.Context, filePath string, content []byte) ([]model.Node, []model.Edge, []treesitter.CommentBlock, error)
-	Language() string
-}
-
 // @intent 메타데이터와 언어 정보까지 돌려주는 parser 확장을 build 경로에서 감지하게 한다.
 type metadataParserWithLanguage interface {
 	Parser