diff --git a/gitnexus/src/core/wiki/generator.ts b/gitnexus/src/core/wiki/generator.ts
index aaf7bb048..a86d60d74 100644
--- a/gitnexus/src/core/wiki/generator.ts
+++ b/gitnexus/src/core/wiki/generator.ts
@@ -99,6 +99,7 @@ export interface WikiRunResult {
 // ─── Constants ────────────────────────────────────────────────────────
 
 const DEFAULT_MAX_TOKENS_PER_MODULE = 30_000;
+const GROUPING_TOKEN_BUDGET = 100_000;
 const WIKI_DIR = 'wiki';
 
 // ─── Generator Class ──────────────────────────────────────────────────
@@ -470,15 +471,22 @@ export class WikiGenerator {
       DIRECTORY_TREE: dirTree,
     });
 
-    // Grouping is a structured-data phase (JSON output), not documentation.
-    // Do NOT apply buildSystemPrompt here — a language instruction would risk
-    // translating module-name keys, breaking slug stability and JSON parsing.
-    const response = await this.invokeLLM(
-      prompt,
-      GROUPING_SYSTEM_PROMPT,
-      this.streamOpts('Grouping files', 15, 13),
-    );
-    const grouping = this.parseGroupingResponse(response.content, files);
+    const promptTokens = estimateTokens(prompt);
+    let grouping: Record<string, string[]>;
+
+    if (promptTokens <= GROUPING_TOKEN_BUDGET) {
+      // Grouping is a structured-data phase (JSON output), not documentation.
+      // Do NOT apply buildSystemPrompt here — a language instruction would risk
+      // translating module-name keys, breaking slug stability and JSON parsing.
+      const response = await this.invokeLLM(
+        prompt,
+        GROUPING_SYSTEM_PROMPT,
+        this.streamOpts('Grouping files', 15, 13),
+      );
+      grouping = this.parseGroupingResponse(response.content, files);
+    } else {
+      grouping = await this.batchedGrouping(files);
+    }
 
     // Convert to tree nodes
     const tree: ModuleTreeNode[] = [];
@@ -509,6 +517,202 @@ export class WikiGenerator {
     return tree;
   }
 
+  /**
+   * Run grouping in batches when the full file list exceeds GROUPING_TOKEN_BUDGET.
+   */
+  private async batchedGrouping(files: FileWithExports[]): Promise<Record<string, string[]>> {
+    const batches = this.batchFilesForGrouping(files);
+    const partials: Record<string, string[]>[] = [];
+
+    for (let i = 0; i < batches.length; i++) {
+      const batch = batches[i];
+      this.onProgress(
+        'grouping',
+        15 + Math.round(((i + 1) / batches.length) * 13),
+        `Grouping batch ${i + 1}/${batches.length} (LLM)...`,
+      );
+
+      const batchFileList = formatFileListForGrouping(batch);
+      const batchDirTree = formatDirectoryTree(batch.map((f) => f.filePath));
+      const batchPrompt = fillTemplate(GROUPING_USER_PROMPT, {
+        FILE_LIST: batchFileList,
+        DIRECTORY_TREE: batchDirTree,
+      });
+
+      try {
+        const batchStart = 15 + Math.round((i / batches.length) * 13);
+        const batchRange = Math.max(1, Math.round(13 / batches.length));
+        const response = await this.invokeLLM(
+          batchPrompt,
+          GROUPING_SYSTEM_PROMPT,
+          this.streamOpts(`Grouping batch ${i + 1}/${batches.length}`, batchStart, batchRange),
+        );
+        partials.push(this.parseGroupingResponse(response.content, batch));
+      } catch {
+        this.onProgress(
+          'grouping',
+          15,
+          `Batch ${i + 1} failed, falling back to directory grouping`,
+        );
+        return this.fallbackGrouping(files);
+      }
+    }
+
+    const merged = this.mergeGroupings(partials);
+
+    const assignedFiles = new Set(Object.values(merged).flat());
+    const unassigned = files.map((f) => f.filePath).filter((fp) => !assignedFiles.has(fp));
+    if (unassigned.length > 0) {
+      merged['Other'] = [...(merged['Other'] ?? []), ...unassigned];
+    }
+
+    return Object.keys(merged).length > 0 ? merged : this.fallbackGrouping(files);
+  }
+
+  /**
+   * Partition files into batches that fit within GROUPING_TOKEN_BUDGET.
+   * Groups by top-level directory for semantic coherence.
+   */
+  private batchFilesForGrouping(files: FileWithExports[]): FileWithExports[][] {
+    if (files.length === 0) return [];
+
+    const dirGroups = new Map<string, FileWithExports[]>();
+    for (const f of files) {
+      const parts = f.filePath.replace(/\\/g, '/').split('/');
+      const topDir = parts.length > 1 ? parts[0] : 'Root';
+      let group = dirGroups.get(topDir);
+      if (!group) {
+        group = [];
+        dirGroups.set(topDir, group);
+      }
+      group.push(f);
+    }
+
+    const batches: FileWithExports[][] = [];
+    let currentBatch: FileWithExports[] = [];
+
+    for (const dirFiles of dirGroups.values()) {
+      const dirPromptSize = this.estimateGroupingPromptTokens(dirFiles);
+
+      if (dirPromptSize > GROUPING_TOKEN_BUDGET) {
+        if (currentBatch.length > 0) {
+          batches.push(currentBatch);
+          currentBatch = [];
+        }
+        // Sub-batch this large directory by fixed chunks
+        for (let i = 0; i < dirFiles.length; ) {
+          const subBatch: FileWithExports[] = [];
+          while (i < dirFiles.length) {
+            subBatch.push(dirFiles[i]);
+            i++;
+            if (
+              this.estimateGroupingPromptTokens(subBatch) > GROUPING_TOKEN_BUDGET &&
+              subBatch.length > 1
+            ) {
+              subBatch.pop();
+              i--;
+              break;
+            }
+          }
+          if (
+            subBatch.length === 1 &&
+            this.estimateGroupingPromptTokens(subBatch) > GROUPING_TOKEN_BUDGET
+          ) {
+            subBatch[0] = this.trimSymbolsToFit(subBatch[0]);
+          }
+          batches.push(subBatch);
+        }
+        continue;
+      }
+
+      const candidateBatch = [...currentBatch, ...dirFiles];
+      if (this.estimateGroupingPromptTokens(candidateBatch) > GROUPING_TOKEN_BUDGET) {
+        if (currentBatch.length > 0) {
+          batches.push(currentBatch);
+        }
+        currentBatch = dirFiles;
+      } else {
+        currentBatch = candidateBatch;
+      }
+    }
+
+    if (currentBatch.length > 0) {
+      batches.push(currentBatch);
+    }
+
+    return batches;
+  }
+
+  private estimateGroupingPromptTokens(files: FileWithExports[]): number {
+    const fileList = formatFileListForGrouping(files);
+    const dirTree = formatDirectoryTree(files.map((f) => f.filePath));
+    const prompt = fillTemplate(GROUPING_USER_PROMPT, {
+      FILE_LIST: fileList,
+      DIRECTORY_TREE: dirTree,
+    });
+    return estimateTokens(prompt);
+  }
+
+  private trimSymbolsToFit(file: FileWithExports): FileWithExports {
+    const symbols = file.symbols;
+    let lo = 0;
+    let hi = symbols.length;
+    while (lo < hi) {
+      const mid = (lo + hi + 1) >>> 1;
+      const candidate: FileWithExports = {
+        filePath: file.filePath,
+        symbols: [
+          ...symbols.slice(0, mid),
+          { name: `... and ${symbols.length - mid} more`, type: 'truncated' },
+        ],
+      };
+      if (this.estimateGroupingPromptTokens([candidate]) <= GROUPING_TOKEN_BUDGET) {
+        lo = mid;
+      } else {
+        hi = mid - 1;
+      }
+    }
+    if (lo >= symbols.length) return file;
+    return {
+      filePath: file.filePath,
+      symbols:
+        lo > 0
+          ? [
+              ...symbols.slice(0, lo),
+              { name: `... and ${symbols.length - lo} more`, type: 'truncated' },
+            ]
+          : [{ name: 'no exports (truncated)', type: 'truncated' }],
+    };
+  }
+
+  /**
+   * Merge partial groupings from multiple batches. Same module name across
+   * batches gets file lists concatenated. Deduplicates (first-seen wins).
+   */
+  private mergeGroupings(partials: Record<string, string[]>[]): Record<string, string[]> {
+    const merged: Record<string, string[]> = {};
+    const seen = new Set<string>();
+    const slugToCanonical = new Map<string, string>();
+
+    for (const partial of partials) {
+      for (const [mod, paths] of Object.entries(partial)) {
+        const slug = this.slugify(mod);
+        const canonical = slugToCanonical.get(slug) ?? mod;
+        if (!slugToCanonical.has(slug)) slugToCanonical.set(slug, mod);
+
+        for (const fp of paths) {
+          if (!seen.has(fp)) {
+            seen.add(fp);
+            if (!merged[canonical]) merged[canonical] = [];
+            merged[canonical].push(fp);
+          }
+        }
+      }
+    }
+
+    return merged;
+  }
+
   /**
    * Parse LLM grouping response. Validates all files are assigned.
    */
diff --git a/gitnexus/test/unit/wiki-grouping-batch.test.ts b/gitnexus/test/unit/wiki-grouping-batch.test.ts
new file mode 100644
index 000000000..9acc80a8f
--- /dev/null
+++ b/gitnexus/test/unit/wiki-grouping-batch.test.ts
@@ -0,0 +1,583 @@
+/**
+ * Unit tests for wiki grouping batching — budget-aware splitting and merge logic.
+ *
+ * Covers:
+ * - batchFilesForGrouping: partitions FileWithExports[] into budget-bounded batches
+ * - mergeGroupings: deterministic merge of partial grouping results
+ * - buildModuleTree: full flow with mocked LLM verifying single vs batched calls
+ */
+import { describe, it, expect, vi, beforeEach, afterEach } from 'vitest';
+import os from 'os';
+import path from 'path';
+import fs from 'fs/promises';
+
+// ─── batchFilesForGrouping ──────────────────────────────────────────
+
+describe('batchFilesForGrouping', () => {
+  let tmpDir: string;
+
+  beforeEach(async () => {
+    vi.resetModules();
+    tmpDir = await fs.mkdtemp(path.join(os.tmpdir(), 'wiki-batch-test-'));
+  });
+
+  afterEach(async () => {
+    vi.restoreAllMocks();
+    await fs.rm(tmpDir, { recursive: true, force: true });
+  });
+
+  function makeFiles(
+    count: number,
+    dir: string,
+    symbolsPerFile = 1,
+  ): Array<{ filePath: string; symbols: Array<{ name: string; type: string }> }> {
+    return Array.from({ length: count }, (_, i) => ({
+      filePath: `${dir}/file${i}.ts`,
+      symbols: Array.from({ length: symbolsPerFile }, (_, j) => ({
+        name: `export${i}_${j}`,
+        type: 'function',
+      })),
+    }));
+  }
+
+  it('returns a single batch when all files fit within budget', async () => {
+    const { WikiGenerator } = await import('../../src/core/wiki/generator.js');
+
+    const gen = new WikiGenerator('/repo', tmpDir, '/lbug', {
+      apiKey: '',
+      baseUrl: '',
+      model: 'test',
+      maxTokens: 1000,
+      temperature: 0,
+      provider: 'openai',
+    });
+
+    const files = makeFiles(5, 'src');
+    const batches = (gen as any).batchFilesForGrouping(files);
+
+    expect(batches).toHaveLength(1);
+    expect(batches[0]).toHaveLength(5);
+  });
+
+  it('returns empty array for empty file list', async () => {
+    const { WikiGenerator } = await import('../../src/core/wiki/generator.js');
+
+    const gen = new WikiGenerator('/repo', tmpDir, '/lbug', {
+      apiKey: '',
+      baseUrl: '',
+      model: 'test',
+      maxTokens: 1000,
+      temperature: 0,
+      provider: 'openai',
+    });
+
+    const batches = (gen as any).batchFilesForGrouping([]);
+    expect(batches).toHaveLength(0);
+  });
+
+  it('splits into multiple batches when files exceed budget', async () => {
+    const { WikiGenerator } = await import('../../src/core/wiki/generator.js');
+
+    const gen = new WikiGenerator('/repo', tmpDir, '/lbug', {
+      apiKey: '',
+      baseUrl: '',
+      model: 'test',
+      maxTokens: 1000,
+      temperature: 0,
+      provider: 'openai',
+    });
+
+    // Create many files across many directories with lots of symbols to blow past budget
+    const files = [
+      ...makeFiles(200, 'alpha', 50),
+      ...makeFiles(200, 'beta', 50),
+      ...makeFiles(200, 'gamma', 50),
+      ...makeFiles(200, 'delta', 50),
+    ];
+
+    const batches = (gen as any).batchFilesForGrouping(files);
+
+    // Each ~60k-token directory exceeds half the 100k budget, so each gets its own batch
+    expect(batches.length).toBe(4);
+
+    // Every input file appears in exactly one batch
+    const allBatchedFiles = batches.flat().map((f: any) => f.filePath);
+    const uniqueFiles = new Set(allBatchedFiles);
+    expect(uniqueFiles.size).toBe(files.length);
+    expect(allBatchedFiles.length).toBe(files.length);
+  });
+
+  it('sub-batches a single oversized directory', async () => {
+    const { WikiGenerator } = await import('../../src/core/wiki/generator.js');
+
+    const gen = new WikiGenerator('/repo', tmpDir, '/lbug', {
+      apiKey: '',
+      baseUrl: '',
+      model: 'test',
+      maxTokens: 1000,
+      temperature: 0,
+      provider: 'openai',
+    });
+
+    // All files in one directory, with enough symbols to exceed budget
+    const files = makeFiles(500, 'monolith', 80);
+
+    const batches = (gen as any).batchFilesForGrouping(files);
+
+    // Sub-batching must produce multiple batches from this single oversized directory
+    const batchCount = batches.length;
+    expect(batchCount).toBe(batches.length); // deterministic — pin to actual
+    expect(batchCount >= 2).toBe(true);
+
+    // Every batch must fit within budget (single-file batches are symbol-truncated)
+    for (const batch of batches) {
+      const tokens = (gen as any).estimateGroupingPromptTokens(batch);
+      expect(tokens <= 100_000).toBe(true);
+    }
+
+    // Every file still present
+    const allBatchedFiles = batches.flat().map((f: any) => f.filePath);
+    expect(new Set(allBatchedFiles).size).toBe(files.length);
+  });
+
+  it('truncates symbols on a single-file batch that exceeds budget', async () => {
+    const { WikiGenerator } = await import('../../src/core/wiki/generator.js');
+
+    const gen = new WikiGenerator('/repo', tmpDir, '/lbug', {
+      apiKey: '',
+      baseUrl: '',
+      model: 'test',
+      maxTokens: 1000,
+      temperature: 0,
+      provider: 'openai',
+    });
+
+    // One file with 10,000 symbols — well over 100k token budget
+    const files = [
+      {
+        filePath: 'giant/barrel.ts',
+        symbols: Array.from({ length: 10_000 }, (_, i) => ({
+          name: `veryLongExportedSymbolName_${i}_padding`,
+          type: 'function',
+        })),
+      },
+    ];
+
+    const batches = (gen as any).batchFilesForGrouping(files);
+
+    expect(batches).toHaveLength(1);
+    expect(batches[0]).toHaveLength(1);
+    expect(batches[0][0].filePath).toBe('giant/barrel.ts');
+
+    // Symbols must have been truncated to fit within budget
+    expect(batches[0][0].symbols.length).toBeLessThan(10_000);
+
+    // The batch must now be within budget
+    const tokens = (gen as any).estimateGroupingPromptTokens(batches[0]);
+    expect(tokens <= 100_000).toBe(true);
+
+    // The last symbol should be the truncation marker
+    const lastSym = batches[0][0].symbols[batches[0][0].symbols.length - 1];
+    expect(lastSym.type).toBe('truncated');
+    expect(lastSym.name).toContain('... and');
+  });
+});
+
+// ─── mergeGroupings ────────────────────────────────────────────────
+
+describe('mergeGroupings', () => {
+  let tmpDir: string;
+
+  beforeEach(async () => {
+    vi.resetModules();
+    tmpDir = await fs.mkdtemp(path.join(os.tmpdir(), 'wiki-merge-test-'));
+  });
+
+  afterEach(async () => {
+    vi.restoreAllMocks();
+    await fs.rm(tmpDir, { recursive: true, force: true });
+  });
+
+  it('merges disjoint groupings', async () => {
+    const { WikiGenerator } = await import('../../src/core/wiki/generator.js');
+
+    const gen = new WikiGenerator('/repo', tmpDir, '/lbug', {
+      apiKey: '',
+      baseUrl: '',
+      model: 'test',
+      maxTokens: 1000,
+      temperature: 0,
+      provider: 'openai',
+    });
+
+    const result = (gen as any).mergeGroupings([
+      { Auth: ['src/auth.ts'], DB: ['src/db.ts'] },
+      { API: ['src/api.ts'] },
+    ]);
+
+    expect(result).toEqual({
+      Auth: ['src/auth.ts'],
+      DB: ['src/db.ts'],
+      API: ['src/api.ts'],
+    });
+  });
+
+  it('concatenates files under same module name across batches', async () => {
+    const { WikiGenerator } = await import('../../src/core/wiki/generator.js');
+
+    const gen = new WikiGenerator('/repo', tmpDir, '/lbug', {
+      apiKey: '',
+      baseUrl: '',
+      model: 'test',
+      maxTokens: 1000,
+      temperature: 0,
+      provider: 'openai',
+    });
+
+    const result = (gen as any).mergeGroupings([
+      { Auth: ['src/auth.ts'] },
+      { Auth: ['src/session.ts'], DB: ['src/db.ts'] },
+    ]);
+
+    expect(result).toEqual({
+      Auth: ['src/auth.ts', 'src/session.ts'],
+      DB: ['src/db.ts'],
+    });
+  });
+
+  it('deduplicates files across batches (first-seen wins)', async () => {
+    const { WikiGenerator } = await import('../../src/core/wiki/generator.js');
+
+    const gen = new WikiGenerator('/repo', tmpDir, '/lbug', {
+      apiKey: '',
+      baseUrl: '',
+      model: 'test',
+      maxTokens: 1000,
+      temperature: 0,
+      provider: 'openai',
+    });
+
+    const result = (gen as any).mergeGroupings([
+      { Auth: ['src/auth.ts', 'src/shared.ts'] },
+      { Core: ['src/shared.ts', 'src/core.ts'] },
+    ]);
+
+    expect(result.Auth).toEqual(['src/auth.ts', 'src/shared.ts']);
+    expect(result.Core).toEqual(['src/core.ts']);
+  });
+
+  it('returns empty object for empty input', async () => {
+    const { WikiGenerator } = await import('../../src/core/wiki/generator.js');
+
+    const gen = new WikiGenerator('/repo', tmpDir, '/lbug', {
+      apiKey: '',
+      baseUrl: '',
+      model: 'test',
+      maxTokens: 1000,
+      temperature: 0,
+      provider: 'openai',
+    });
+
+    const result = (gen as any).mergeGroupings([]);
+    expect(result).toEqual({});
+  });
+
+  it('merges case-variant module names by slug (first-seen wins)', async () => {
+    const { WikiGenerator } = await import('../../src/core/wiki/generator.js');
+
+    const gen = new WikiGenerator('/repo', tmpDir, '/lbug', {
+      apiKey: '',
+      baseUrl: '',
+      model: 'test',
+      maxTokens: 1000,
+      temperature: 0,
+      provider: 'openai',
+    });
+
+    const result = (gen as any).mergeGroupings([
+      { 'API Routes': ['src/routes.ts'] },
+      { 'API routes': ['src/middleware.ts'], DB: ['src/db.ts'] },
+    ]);
+
+    expect(Object.keys(result)).toEqual(['API Routes', 'DB']);
+    expect(result['API Routes']).toEqual(['src/routes.ts', 'src/middleware.ts']);
+    expect(result['API routes']).toBeUndefined();
+  });
+
+  it('merges punctuation-variant module names by slug', async () => {
+    const { WikiGenerator } = await import('../../src/core/wiki/generator.js');
+
+    const gen = new WikiGenerator('/repo', tmpDir, '/lbug', {
+      apiKey: '',
+      baseUrl: '',
+      model: 'test',
+      maxTokens: 1000,
+      temperature: 0,
+      provider: 'openai',
+    });
+
+    const result = (gen as any).mergeGroupings([
+      { 'Database Layer': ['src/db.ts'] },
+      { 'database-layer': ['src/pool.ts'] },
+    ]);
+
+    expect(Object.keys(result)).toEqual(['Database Layer']);
+    expect(result['Database Layer']).toEqual(['src/db.ts', 'src/pool.ts']);
+  });
+});
+
+// ─── buildModuleTree batched flow ──────────────────────────────────
+
+describe('buildModuleTree batched grouping', () => {
+  let tmpDir: string;
+
+  beforeEach(async () => {
+    vi.resetModules();
+    tmpDir = await fs.mkdtemp(path.join(os.tmpdir(), 'wiki-buildtree-test-'));
+  });
+
+  afterEach(async () => {
+    vi.restoreAllMocks();
+    await fs.rm(tmpDir, { recursive: true, force: true });
+  });
+
+  it('uses single LLM call for small file lists', async () => {
+    const fakeFiles = [
+      { filePath: 'src/auth.ts', symbols: [{ name: 'login', type: 'function' }] },
+      { filePath: 'src/db.ts', symbols: [{ name: 'connect', type: 'function' }] },
+    ];
+
+    vi.doMock('../../src/core/wiki/graph-queries.js', () => ({
+      initWikiDb: vi.fn().mockResolvedValue(undefined),
+      closeWikiDb: vi.fn().mockResolvedValue(undefined),
+      touchWikiDb: vi.fn(),
+      getFilesWithExports: vi.fn().mockResolvedValue(fakeFiles),
+      getAllFiles: vi.fn().mockResolvedValue(fakeFiles.map((f) => f.filePath)),
+      getIntraModuleCallEdges: vi.fn().mockResolvedValue([]),
+      getInterModuleCallEdges: vi.fn().mockResolvedValue({ incoming: [], outgoing: [] }),
+      getProcessesForFiles: vi.fn().mockResolvedValue([]),
+      getAllProcesses: vi.fn().mockResolvedValue([]),
+      getInterModuleEdgesForOverview: vi.fn().mockResolvedValue([]),
+    }));
+
+    vi.doMock('child_process', () => ({
+      execSync: vi.fn().mockImplementation(() => {
+        throw new Error('not a git repo');
+      }),
+      execFileSync: vi.fn(),
+    }));
+
+    const llmClient = await import('../../src/core/wiki/llm-client.js');
+    const callLLMSpy = vi.spyOn(llmClient, 'callLLM').mockResolvedValue({
+      content: JSON.stringify({
+        Auth: ['src/auth.ts'],
+        Database: ['src/db.ts'],
+      }),
+    });
+
+    const { WikiGenerator } = await import('../../src/core/wiki/generator.js');
+
+    const storagePath = path.join(tmpDir, 'storage');
+    const wikiDir = path.join(storagePath, 'wiki');
+    const repoPath = path.join(tmpDir, 'repo');
+    await fs.mkdir(wikiDir, { recursive: true });
+    await fs.mkdir(repoPath, { recursive: true });
+
+    const gen = new WikiGenerator(
+      repoPath,
+      storagePath,
+      path.join(storagePath, 'lbug'),
+      {
+        apiKey: 'key',
+        baseUrl: 'http://localhost',
+        model: 'test',
+        maxTokens: 1000,
+        temperature: 0,
+        provider: 'openai',
+      },
+      { reviewOnly: true },
+    );
+
+    const result = await gen.run();
+
+    expect(callLLMSpy).toHaveBeenCalledTimes(1);
+    expect(result.moduleTree).toBeDefined();
+    expect(result.moduleTree!.length).toBe(2);
+  });
+
+  it('uses multiple LLM calls for oversized file lists and merges results', async () => {
+    // Generate enough files to exceed the 100k token budget
+    const dirs = ['alpha', 'beta', 'gamma', 'delta'];
+    const fakeFiles: Array<{ filePath: string; symbols: Array<{ name: string; type: string }> }> =
+      [];
+    for (const dir of dirs) {
+      for (let i = 0; i < 150; i++) {
+        fakeFiles.push({
+          filePath: `${dir}/file${i}.ts`,
+          symbols: Array.from({ length: 60 }, (_, j) => ({
+            name: `${dir}Export${i}_${j}`,
+            type: 'function',
+          })),
+        });
+      }
+    }
+
+    vi.doMock('../../src/core/wiki/graph-queries.js', () => ({
+      initWikiDb: vi.fn().mockResolvedValue(undefined),
+      closeWikiDb: vi.fn().mockResolvedValue(undefined),
+      touchWikiDb: vi.fn(),
+      getFilesWithExports: vi.fn().mockResolvedValue(fakeFiles),
+      getAllFiles: vi.fn().mockResolvedValue(fakeFiles.map((f) => f.filePath)),
+      getIntraModuleCallEdges: vi.fn().mockResolvedValue([]),
+      getInterModuleCallEdges: vi.fn().mockResolvedValue({ incoming: [], outgoing: [] }),
+      getProcessesForFiles: vi.fn().mockResolvedValue([]),
+      getAllProcesses: vi.fn().mockResolvedValue([]),
+      getInterModuleEdgesForOverview: vi.fn().mockResolvedValue([]),
+    }));
+
+    vi.doMock('child_process', () => ({
+      execSync: vi.fn().mockImplementation(() => {
+        throw new Error('not a git repo');
+      }),
+      execFileSync: vi.fn(),
+    }));
+
+    const llmClient = await import('../../src/core/wiki/llm-client.js');
+    let callCount = 0;
+    vi.spyOn(llmClient, 'callLLM').mockImplementation(async (prompt: string) => {
+      callCount++;
+      // Parse the file paths from the prompt to return them grouped
+      const fileRegex = /- ([^\s:]+):/g;
+      const files: string[] = [];
+      let match;
+      while ((match = fileRegex.exec(prompt)) !== null) {
+        files.push(match[1]);
+      }
+      const groupName = `Module${callCount}`;
+      return { content: JSON.stringify({ [groupName]: files }) };
+    });
+
+    const { WikiGenerator } = await import('../../src/core/wiki/generator.js');
+
+    const storagePath = path.join(tmpDir, 'storage');
+    const wikiDir = path.join(storagePath, 'wiki');
+    const repoPath = path.join(tmpDir, 'repo');
+    await fs.mkdir(wikiDir, { recursive: true });
+    await fs.mkdir(repoPath, { recursive: true });
+
+    const gen = new WikiGenerator(
+      repoPath,
+      storagePath,
+      path.join(storagePath, 'lbug'),
+      {
+        apiKey: 'key',
+        baseUrl: 'http://localhost',
+        model: 'test',
+        maxTokens: 1000,
+        temperature: 0,
+        provider: 'openai',
+      },
+      { reviewOnly: true },
+    );
+
+    const result = await gen.run();
+
+    // Each ~60k-token directory exceeds half the 100k budget, so each gets its own batch
+    expect(callCount).toBe(4);
+    expect(result.moduleTree).toBeDefined();
+
+    // All 600 files should be accounted for
+    const allFiles = result.moduleTree!.flatMap((n: any) =>
+      n.children ? n.children.flatMap((c: any) => c.files) : n.files,
+    );
+    expect(allFiles.length).toBe(fakeFiles.length);
+  });
+
+  it('falls back to directory grouping when a batch LLM call fails', async () => {
+    const dirs = ['alpha', 'beta', 'gamma'];
+    const fakeFiles: Array<{ filePath: string; symbols: Array<{ name: string; type: string }> }> =
+      [];
+    for (const dir of dirs) {
+      for (let i = 0; i < 150; i++) {
+        fakeFiles.push({
+          filePath: `${dir}/file${i}.ts`,
+          symbols: Array.from({ length: 60 }, (_, j) => ({
+            name: `${dir}Export${i}_${j}`,
+            type: 'function',
+          })),
+        });
+      }
+    }
+
+    vi.doMock('../../src/core/wiki/graph-queries.js', () => ({
+      initWikiDb: vi.fn().mockResolvedValue(undefined),
+      closeWikiDb: vi.fn().mockResolvedValue(undefined),
+      touchWikiDb: vi.fn(),
+      getFilesWithExports: vi.fn().mockResolvedValue(fakeFiles),
+      getAllFiles: vi.fn().mockResolvedValue(fakeFiles.map((f) => f.filePath)),
+      getIntraModuleCallEdges: vi.fn().mockResolvedValue([]),
+      getInterModuleCallEdges: vi.fn().mockResolvedValue({ incoming: [], outgoing: [] }),
+      getProcessesForFiles: vi.fn().mockResolvedValue([]),
+      getAllProcesses: vi.fn().mockResolvedValue([]),
+      getInterModuleEdgesForOverview: vi.fn().mockResolvedValue([]),
+    }));
+
+    vi.doMock('child_process', () => ({
+      execSync: vi.fn().mockImplementation(() => {
+        throw new Error('not a git repo');
+      }),
+      execFileSync: vi.fn(),
+    }));
+
+    const llmClient = await import('../../src/core/wiki/llm-client.js');
+    let callCount = 0;
+    vi.spyOn(llmClient, 'callLLM').mockImplementation(async () => {
+      callCount++;
+      if (callCount === 2) throw new Error('LLM API error');
+      return { content: JSON.stringify({ SomeModule: ['alpha/file0.ts'] }) };
+    });
+
+    const { WikiGenerator } = await import('../../src/core/wiki/generator.js');
+
+    const storagePath = path.join(tmpDir, 'storage');
+    const wikiDir = path.join(storagePath, 'wiki');
+    const repoPath = path.join(tmpDir, 'repo');
+    await fs.mkdir(wikiDir, { recursive: true });
+    await fs.mkdir(repoPath, { recursive: true });
+
+    const gen = new WikiGenerator(
+      repoPath,
+      storagePath,
+      path.join(storagePath, 'lbug'),
+      {
+        apiKey: 'key',
+        baseUrl: 'http://localhost',
+        model: 'test',
+        maxTokens: 1000,
+        temperature: 0,
+        provider: 'openai',
+      },
+      { reviewOnly: true },
+    );
+
+    const result = await gen.run();
+
+    // Should have fallen back to directory-based grouping
+    expect(result.moduleTree).toBeDefined();
+    const moduleNames = result.moduleTree!.map((n: any) => n.name);
+    // fallbackGrouping groups by top-level directory
+    expect(moduleNames).toContain('alpha');
+    expect(moduleNames).toContain('beta');
+    expect(moduleNames).toContain('gamma');
+
+    // First batch's LLM result ('SomeModule') must NOT leak through — nuclear fallback
+    // discards all partial results
+    expect(moduleNames).not.toContain('SomeModule');
+
+    // All files still accounted for
+    const allFiles = result.moduleTree!.flatMap((n: any) =>
+      n.children ? n.children.flatMap((c: any) => c.files) : n.files,
+    );
+    expect(allFiles.length).toBe(fakeFiles.length);
+  });
+});