Fix codebase indexing for plain text files

src/services/code-index/processors/__tests__/parser.txt.spec.ts

@@ -0,0 +1,42 @@
+import { CodeParser } from "../parser"
+import { scannerExtensions, shouldUseFallbackChunking } from "../../shared/supported-extensions"
+
+vi.mock("../../../../../packages/telemetry/src/TelemetryService", () => ({
+	TelemetryService: {
+		instance: {
+			captureEvent: vi.fn(),
+		},
+	},
+}))
+
+describe("CodeParser - plain text support", () => {
+	it("supports .txt files through fallback chunking", async () => {
+		expect(scannerExtensions).toContain(".txt")
+		expect(shouldUseFallbackChunking(".txt")).toBe(true)
+
+		const content = [
+			"Zoo Code plain text indexing regression test.",
+			"This sentence contains searchable content that only exists in the text file.",
+			"The fallback parser should preserve every line while creating an indexable chunk.",
+		].join("\n")
+
+		const blocks = await new CodeParser().parseFile("manual.txt", {
+			content,
+			fileHash: "txt-file-hash",
+		})
+
+		expect(blocks).toHaveLength(1)
+		expect(blocks[0]).toMatchObject({
+			file_path: "manual.txt",
+			type: "fallback_chunk",
+			start_line: 1,
+			end_line: 3,
+			content,
+			fileHash: "txt-file-hash",
+		})
+	})
+
+	it("matches uppercase .TXT extensions", () => {
+		expect(shouldUseFallbackChunking(".TXT")).toBe(true)
+	})
+})

src/services/code-index/shared/supported-extensions.ts

@@ -19,6 +19,7 @@ export const scannerExtensions = allExtensions
  * Note: Do NOT remove parser cases from languageParser.ts as they may be used elsewhere
  */
 export const fallbackExtensions = [
+	".txt", // Plain text - no tree-sitter parser needed
 	".vb", // Visual Basic .NET - no dedicated WASM parser
 	".scala", // Scala - uses fallback chunking instead of Lua query workaround
 	".swift", // Swift - uses fallback chunking due to parser instability

src/services/tree-sitter/__tests__/plainTextIntegration.spec.ts

@@ -0,0 +1,31 @@
+// Mocks must come first, before imports
+
+vi.mock("fs/promises", () => ({
+	readFile: vi.fn(),
+}))
+
+vi.mock("../../../utils/fs", () => ({
+	fileExistsAtPath: vi.fn().mockResolvedValue(true),
+}))
+
+vi.mock("../languageParser", () => ({
+	loadRequiredLanguageParsers: vi.fn(),
+}))
+
+import * as fs from "fs/promises"
+import { loadRequiredLanguageParsers } from "../languageParser"
+import { parseSourceCodeDefinitionsForFile } from "../index"
+
+describe("Plain Text Integration Tests", () => {
+	beforeEach(() => {
+		vi.clearAllMocks()
+	})
+
+	it("returns undefined without loading a tree-sitter parser", async () => {
+		const result = await parseSourceCodeDefinitionsForFile("manual.txt")
+
+		expect(result).toBeUndefined()
+		expect(loadRequiredLanguageParsers).not.toHaveBeenCalled()
+		expect(fs.readFile).not.toHaveBeenCalled()
+	})
+})

src/services/tree-sitter/index.ts

@@ -66,6 +66,8 @@ const extensions = [
 	// Markdown
 	"md",
 	"markdown",
+	// Plain text
+	"txt",
 	// JSON
 	"json",
 	// CSS
@@ -111,6 +113,11 @@ export async function parseSourceCodeDefinitionsForFile(
 		return undefined
 	}
 
+	// Plain text files have no structural definitions to extract
+	if (ext === ".txt") {
+		return undefined
+	}
+
 	// Special case for markdown files
 	if (ext === ".md" || ext === ".markdown") {
 		// Check if we have permission to access this file