feat(lsp): add Rename Symbol support (T001-T005)

[Auto-checkpoint from /please:dev Phase 6]

Tasks completed:
- T001: Add type schemas (TextEdit, WorkspaceEdit, PrepareRenameResult)
- T002: Add rename capability to client initialization
- T003: Add normalization methods (normalizeWorkspaceEdit, normalizePrepareRename)
- T004: Add prepareRename() method
- T005: Add rename() method

Issue: #18

Author: amondnet

.please/memory/tasklist.json

@@ -1,19 +1,50 @@
 {
-  "session_id": "20251217-oxc-formatter-support",
-  "feature_name": "Add oxc formatter (oxfmt) support to packages/format",
-  "created_at": "2025-12-17T10:00:00Z",
-  "updated_at": "2025-12-17T10:00:00Z",
+  "session_id": "20251218-rename-symbol-lsp",
+  "feature_name": "Add Rename Symbol support to @pleaseai/code-lsp",
+  "created_at": "2025-12-18T10:00:00Z",
+  "updated_at": "2025-12-18T10:00:00Z",
   "status": "in_progress",
-  "current_phase": 1,
+  "current_phase": 6,
+  "issue_number": 18,
+  "branch": "18-featlsp-add-rename-symbol-support",
+  "spec": {
+    "path": "specs/001-rename-symbol/spec.md",
+    "number": 1,
+    "short_name": "rename-symbol",
+    "created_at": "2025-12-18T10:25:00Z",
+    "clarified_at": "2025-12-18T10:30:00Z"
+  },
+  "checkpoint_config": {
+    "mode": "auto",
+    "push_strategy": "batch",
+    "validation_required": true
+  },
+  "ralph_config": {
+    "enabled": true,
+    "max_iterations": 50,
+    "completion_promise": "ALL_PHASE6_TASKS_COMPLETED",
+    "current_iteration": 0,
+    "started_at": "2025-12-18T10:50:00Z"
+  },
   "phases": [
-    { "number": 1, "name": "Discovery", "status": "in_progress", "started_at": "2025-12-17T10:00:00Z" },
-    { "number": 2, "name": "Codebase Exploration", "status": "pending" },
-    { "number": 3, "name": "Clarifying Questions", "status": "pending" },
-    { "number": 4, "name": "Architecture Design", "status": "pending" },
-    { "number": 5, "name": "GitHub Issue & PR", "status": "pending" },
-    { "number": 6, "name": "Implementation", "status": "pending" },
+    { "number": 1, "name": "Discovery", "status": "completed", "started_at": "2025-12-18T10:00:00Z", "completed_at": "2025-12-18T10:05:00Z" },
+    { "number": 2, "name": "Codebase Exploration", "status": "completed", "started_at": "2025-12-18T10:05:00Z", "completed_at": "2025-12-18T10:20:00Z" },
+    { "number": 3, "name": "Specification & Clarification", "status": "completed", "started_at": "2025-12-18T10:20:00Z", "completed_at": "2025-12-18T10:30:00Z" },
+    { "number": 4, "name": "Architecture Design", "status": "completed", "started_at": "2025-12-18T10:30:00Z", "completed_at": "2025-12-18T10:45:00Z" },
+    { "number": 5, "name": "GitHub Issue & PR", "status": "completed", "started_at": "2025-12-18T10:45:00Z", "completed_at": "2025-12-18T10:50:00Z" },
+    { "number": 6, "name": "Implementation", "status": "in_progress", "started_at": "2025-12-18T10:50:00Z" },
     { "number": 7, "name": "Quality Review", "status": "pending" },
     { "number": 8, "name": "PR Finalization", "status": "pending" }
   ],
-  "tasks": []
+  "tasks": [
+    { "id": "T001", "title": "Add type schemas (TextEdit, WorkspaceEdit, PrepareRenameResult)", "phase": 6, "status": "pending", "parallel": true, "dependencies": [] },
+    { "id": "T002", "title": "Add rename capability to client initialization", "phase": 6, "status": "pending", "parallel": true, "dependencies": [] },
+    { "id": "T003", "title": "Add normalization methods", "phase": 6, "status": "pending", "parallel": false, "dependencies": ["T001"] },
+    { "id": "T004", "title": "Add prepareRename() method", "phase": 6, "status": "pending", "parallel": false, "dependencies": ["T001", "T003"] },
+    { "id": "T005", "title": "Add rename() method", "phase": 6, "status": "pending", "parallel": false, "dependencies": ["T001", "T003"] },
+    { "id": "T006", "title": "Update CLAUDE.md documentation", "phase": 6, "status": "pending", "parallel": false, "dependencies": ["T004", "T005"] },
+    { "id": "T007", "title": "Add unit tests for normalization", "phase": 6, "status": "pending", "parallel": true, "dependencies": [] },
+    { "id": "T008", "title": "Add integration tests", "phase": 6, "status": "pending", "parallel": false, "dependencies": ["T004", "T005"] }
+  ],
+  "checkpoints": []
 }

packages/lsp/src/client.ts

@@ -125,6 +125,7 @@ export async function createLSPClient(input: {
         textDocument: {
           synchronization: { didOpen: true, didChange: true },
           publishDiagnostics: { versionSupport: true },
+          rename: { prepareSupport: true },
         },
       },
     }),

packages/lsp/src/index.ts

@@ -142,6 +142,40 @@ export const DocumentSymbolSchema = z.object({
 })
 export type DocumentSymbol = z.infer<typeof DocumentSymbolSchema>
 
+/**
+ * LSP TextEdit schema
+ * A textual edit applicable to a text document.
+ * @see https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification/#textEdit
+ */
+export const TextEditSchema = z.object({
+  range: RangeSchema,
+  newText: z.string(),
+})
+export type TextEdit = z.infer<typeof TextEditSchema>
+
+/**
+ * LSP WorkspaceEdit schema
+ * A workspace edit represents changes to many resources managed in the workspace.
+ * @see https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification/#workspaceEdit
+ */
+export const WorkspaceEditSchema = z.object({
+  changes: z.record(z.string(), z.array(TextEditSchema)).optional(),
+})
+export type WorkspaceEdit = z.infer<typeof WorkspaceEditSchema>
+
+/**
+ * LSP PrepareRenameResult schema
+ * The result of a prepareRename request.
+ * Can be: Range, { range, placeholder }, or { defaultBehavior }
+ * @see https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification/#textDocument_prepareRename
+ */
+export const PrepareRenameResultSchema = z.union([
+  RangeSchema,
+  z.object({ range: RangeSchema, placeholder: z.string() }),
+  z.object({ defaultBehavior: z.boolean() }),
+])
+export type PrepareRenameResult = z.infer<typeof PrepareRenameResultSchema>
+
 /**
  * LSP Status
  */
@@ -645,6 +679,156 @@ export class LSPManager {
     )
   }
 
+  /**
+   * Type guard for Range
+   */
+  private isRange(obj: unknown): obj is Range {
+    return (
+      typeof obj === 'object'
+      && obj !== null
+      && 'start' in obj
+      && 'end' in obj
+    )
+  }
+
+  /**
+   * Normalize WorkspaceEdit response
+   * Handles both 'changes' and 'documentChanges' formats
+   * Based on Serena: ls_types.py:extract_text_edits
+   */
+  private normalizeWorkspaceEdit(result: unknown): WorkspaceEdit | null {
+    if (!result || typeof result !== 'object')
+      return null
+
+    const edit = result as Record<string, unknown>
+
+    // Handle 'changes' format (preferred, simpler)
+    if ('changes' in edit && edit.changes) {
+      return { changes: edit.changes as Record<string, TextEdit[]> }
+    }
+
+    // Handle 'documentChanges' format - normalize to 'changes'
+    if ('documentChanges' in edit && Array.isArray(edit.documentChanges)) {
+      const changes: Record<string, TextEdit[]> = {}
+      for (const change of edit.documentChanges) {
+        if (
+          typeof change === 'object'
+          && change !== null
+          && 'textDocument' in change
+          && 'edits' in change
+        ) {
+          const uri = (change as { textDocument: { uri: string } }).textDocument.uri
+          changes[uri] = (change as { edits: TextEdit[] }).edits
+        }
+      }
+      if (Object.keys(changes).length > 0) {
+        return { changes }
+      }
+    }
+
+    return null
+  }
+
+  /**
+   * Normalize PrepareRenameResult response
+   * Handles: Range, { range, placeholder }, or { defaultBehavior }
+   */
+  private normalizePrepareRename(result: unknown): PrepareRenameResult | null {
+    if (!result)
+      return null
+
+    // Format 1: Just a Range
+    if (this.isRange(result)) {
+      return result
+    }
+
+    // Format 2: { range, placeholder }
+    if (
+      typeof result === 'object'
+      && 'range' in result
+      && 'placeholder' in result
+    ) {
+      return result as { range: Range, placeholder: string }
+    }
+
+    // Format 3: { defaultBehavior }
+    if (typeof result === 'object' && 'defaultBehavior' in result) {
+      return result as { defaultBehavior: boolean }
+    }
+
+    return null
+  }
+
+  /**
+   * Prepare rename at the given position
+   * Validates if the symbol at the position can be renamed
+   *
+   * @see https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification/#textDocument_prepareRename
+   */
+  async prepareRename(input: {
+    file: string
+    line: number
+    character: number
+  }): Promise<PrepareRenameResult | null> {
+    const clients = await this.getClients(input.file)
+
+    const results = await Promise.all(
+      clients.map(client =>
+        client.connection
+          .sendRequest('textDocument/prepareRename', {
+            textDocument: {
+              uri: pathToFileURL(input.file).href,
+            },
+            position: {
+              line: input.line,
+              character: input.character,
+            },
+          })
+          .then((result: unknown) => this.normalizePrepareRename(result))
+          .catch(() => null),
+      ),
+    )
+
+    // Return first non-null result (only one server typically owns rename)
+    return results.find(r => r !== null) ?? null
+  }
+
+  /**
+   * Rename the symbol at the given position
+   * Returns a WorkspaceEdit with all changes needed
+   *
+   * @see https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification/#textDocument_rename
+   */
+  async rename(input: {
+    file: string
+    line: number
+    character: number
+    newName: string
+  }): Promise<WorkspaceEdit | null> {
+    const clients = await this.getClients(input.file)
+
+    const results = await Promise.all(
+      clients.map(client =>
+        client.connection
+          .sendRequest('textDocument/rename', {
+            textDocument: {
+              uri: pathToFileURL(input.file).href,
+            },
+            position: {
+              line: input.line,
+              character: input.character,
+            },
+            newName: input.newName,
+          })
+          .then((result: unknown) => this.normalizeWorkspaceEdit(result))
+          .catch(() => null),
+      ),
+    )
+
+    // Return first non-null result (only one server typically owns rename)
+    return results.find(r => r !== null) ?? null
+  }
+
   /**
    * Shutdown all clients
    */