feat(mcp): normalize impact and context parameter aliases

gitnexus/src/mcp/local/local-backend.ts

@@ -142,6 +142,61 @@ function resolveAliasString(canonical: unknown, legacy: unknown): string | undef
   return undefined;
 }
 
+interface StringAliasDefinition {
+  canonical: string;
+  aliases: readonly string[];
+}
+
+const TOOL_STRING_ALIASES: Readonly<Record<string, readonly StringAliasDefinition[]>> = {
+  impact: [{ canonical: 'target', aliases: ['name', 'symbol'] }],
+  context: [{ canonical: 'file_path', aliases: ['file'] }],
+};
+
+function normalizeToolParams(
+  method: string,
+  params: unknown,
+): { params: Record<string, unknown> } | { error: string } {
+  const input = params && typeof params === 'object' ? (params as Record<string, unknown>) : {};
+  const definitions = TOOL_STRING_ALIASES[method];
+  if (!definitions) return { params: input };
+
+  const normalized = { ...input };
+  for (const { canonical, aliases } of definitions) {
+    const keys = [canonical, ...aliases];
+    const supplied: Array<{ key: string; value: string }> = [];
+    for (const key of keys) {
+      if (!Object.prototype.hasOwnProperty.call(input, key)) continue;
+      const value = input[key];
+      // Internal CLI callers materialize omitted optional flags as undefined.
+      if (value === undefined) continue;
+      if (typeof value !== 'string' || !value.trim()) {
+        return { error: `MCP parameter ${method}.${key} must be a non-empty string.` };
+      }
+      supplied.push({ key, value: value.trim() });
+    }
+    const distinctValues = new Set(supplied.map(({ value }) => value));
+    if (distinctValues.size > 1) {
+      return {
+        error: `Conflicting MCP parameters for ${method}.${canonical}: ${supplied
+          .map(({ key }) => key)
+          .join(', ')} must agree.`,
+      };
+    }
+
+    for (const alias of aliases) delete normalized[alias];
+    if (supplied.length > 0) normalized[canonical] = supplied[0].value;
+  }
+
+  if (
+    method === 'impact' &&
+    typeof normalized.target !== 'string' &&
+    (typeof normalized.target_uid !== 'string' || !normalized.target_uid.trim())
+  ) {
+    return { error: 'MCP impact requires target, name, symbol, or target_uid.' };
+  }
+  return { params: normalized };
+}
+
 // AI context generation is CLI-only (gitnexus analyze)
 // import { generateAIContextFiles } from '../../cli/ai-context.js';
 
@@ -1661,7 +1716,9 @@ export class LocalBackend {
       return this.handleGroupTool(method, params || {});
     }
 
-    const p = params && typeof params === 'object' ? (params as Record<string, unknown>) : {};
+    const normalized = normalizeToolParams(method, params);
+    if ('error' in normalized) return { error: normalized.error };
+    const p = normalized.params;
 
     // #2175: Claude Code drops a tool-call argument named exactly "query", so the
     // query/cypher tools advertise "search_query"/"statement" while still accepting the
@@ -1682,47 +1739,52 @@ export class LocalBackend {
 
     // Resolve repo from optional param (re-reads registry on miss). An optional
     // `branch` param scopes the resolved handle to that branch's index (#2106).
-    const repoParams = params as { repo?: string; branch?: string } | undefined;
-    const repo = await this.resolveRepo(repoParams?.repo, repoParams?.branch);
+    const repo = await this.resolveRepo(
+      p.repo as string | undefined,
+      p.branch as string | undefined,
+    );
 
     switch (method) {
       case 'query':
-        return this.query(repo, params);
+        return this.query(repo, p);
       case 'cypher': {
-        const raw = await this.cypher(repo, params);
+        const raw = await this.cypher(repo, p);
         return this.formatCypherAsMarkdown(raw);
       }
       case 'context':
-        return this.context(repo, params);
+        return this.context(repo, p);
       case 'explain':
-        return this.explain(repo, params);
+        return this.explain(repo, p);
       case 'pdg_query':
-        return this.pdgQuery(repo, params);
+        return this.pdgQuery(repo, p);
       case 'impact':
-        return this.impact(repo, params);
+        return this.impact(repo, p as unknown as ImpactParams);
       case 'detect_changes':
-        return this.detectChanges(repo, params);
+        return this.detectChanges(repo, p);
       case 'check':
-        return this.check(repo, params);
+        return this.check(repo, p);
       case 'rename':
-        return this.rename(repo, params);
+        return this.rename(repo, p as unknown as Parameters<LocalBackend['rename']>[1]);
       // Legacy aliases for backwards compatibility
       case 'search':
-        return this.query(repo, params);
+        return this.query(repo, p);
       case 'explore':
-        return this.context(repo, { name: params?.name, ...params });
+        return this.context(repo, {
+          name: typeof p.name === 'string' ? p.name : undefined,
+          ...p,
+        });
       case 'overview':
-        return this.overview(repo, params);
+        return this.overview(repo, p);
       case 'route_map':
-        return this.routeMap(repo, params);
+        return this.routeMap(repo, p);
       case 'shape_check':
-        return this.shapeCheck(repo, params);
+        return this.shapeCheck(repo, p);
       case 'tool_map':
-        return this.toolMap(repo, params);
+        return this.toolMap(repo, p);
       case 'api_impact':
-        return this.apiImpact(repo, params);
+        return this.apiImpact(repo, p);
       case 'trace':
-        return this.trace(repo, params);
+        return this.trace(repo, p);
       default:
         throw new Error(`Unknown tool: ${method}`);
     }

gitnexus/src/mcp/tools.ts

@@ -297,6 +297,10 @@ SERVICE: optional monorepo path prefix (case-sensitive path segments). When "rep
           description: 'Direct symbol UID from prior tool results (zero-ambiguity lookup)',
         },
         file_path: { type: 'string', description: 'File path to disambiguate common names' },
+        file: {
+          type: 'string',
+          description: 'Compatibility alias for file_path; values must agree when both are present',
+        },
         kind: {
           type: 'string',
           description:
@@ -461,6 +465,14 @@ SERVICE: optional monorepo path prefix (case-sensitive path segments). When "rep
       type: 'object',
       properties: {
         target: { type: 'string', description: 'Name of function, class, or file to analyze' },
+        name: {
+          type: 'string',
+          description: 'Compatibility alias for target; all supplied target aliases must agree',
+        },
+        symbol: {
+          type: 'string',
+          description: 'Compatibility alias for target; all supplied target aliases must agree',
+        },
         target_uid: {
           type: 'string',
           description:
@@ -578,7 +590,7 @@ SERVICE: optional monorepo path prefix (case-sensitive path segments). When "rep
           maximum: 3600000,
         },
       },
-      required: ['target', 'direction'],
+      required: ['direction'],
     },
   },
   {

gitnexus/test/integration/local-backend-calltool.test.ts

@@ -102,6 +102,31 @@ withTestLbugDB(
         expect(depNames).toContain('login');
       });
 
+      it.each(['name', 'symbol'] as const)(
+        'impact tool resolves the %s compatibility alias against a real index',
+        async (alias) => {
+          const result = await backend.callTool('impact', {
+            [alias]: 'validate',
+            direction: 'upstream',
+          });
+          expect(result).not.toHaveProperty('error');
+          expect(result.target?.name).toBe('validate');
+          const directDeps = result.byDepth[1] || result.byDepth['1'] || [];
+          expect(directDeps.map((d: any) => d.name)).toContain('login');
+        },
+      );
+
+      it('context tool resolves the file compatibility alias against a real index', async () => {
+        const result = await backend.callTool('context', {
+          name: 'authenticate',
+          file: 'src/base.ts',
+        });
+        expect(result).not.toHaveProperty('error');
+        expect(result.status).toBe('found');
+        expect(result.symbol?.name).toBe('authenticate');
+        expect(result.symbol?.filePath).toBe('src/base.ts');
+      });
+
       it('query tool returns results for keyword search', async () => {
         const result = await backend.callTool('query', { query: 'login' });
         expect(result).not.toHaveProperty('error');

gitnexus/test/unit/calltool-dispatch.test.ts

@@ -327,6 +327,138 @@ describe('LocalBackend.callTool', () => {
     );
   });
 
+  it.each(['name', 'symbol'] as const)(
+    'normalizes impact.%s to target once before local dispatch',
+    async (alias) => {
+      const impactSpy = vi
+        .spyOn(backend as any, 'impact')
+        .mockResolvedValue({ status: 'normalized' });
+
+      const result = await backend.callTool('impact', {
+        [alias]: ' validate ',
+        direction: 'upstream',
+      });
+
+      expect(result).toEqual({ status: 'normalized' });
+      const dispatched = impactSpy.mock.calls[0][1] as Record<string, unknown>;
+      expect(dispatched.target).toBe('validate');
+      expect(dispatched).not.toHaveProperty('name');
+      expect(dispatched).not.toHaveProperty('symbol');
+    },
+  );
+
+  it('normalizes context.file to file_path once before local dispatch', async () => {
+    const contextSpy = vi
+      .spyOn(backend as any, 'context')
+      .mockResolvedValue({ status: 'normalized' });
+
+    const result = await backend.callTool('context', {
+      name: 'validate',
+      file: ' src/auth.ts ',
+    });
+
+    expect(result).toEqual({ status: 'normalized' });
+    const dispatched = contextSpy.mock.calls[0][1] as Record<string, unknown>;
+    expect(dispatched.file_path).toBe('src/auth.ts');
+    expect(dispatched).not.toHaveProperty('file');
+  });
+
+  it('treats undefined optional alias keys from CLI callers as absent', async () => {
+    const contextSpy = vi
+      .spyOn(backend as any, 'context')
+      .mockResolvedValue({ status: 'normalized' });
+
+    const result = await backend.callTool('context', {
+      name: 'validate',
+      file_path: undefined,
+      file: undefined,
+    });
+
+    expect(result).toEqual({ status: 'normalized' });
+    expect(contextSpy.mock.calls[0][1]).toMatchObject({ name: 'validate' });
+  });
+
+  it('allows agreeing canonical and alias values after trimming', async () => {
+    const impactSpy = vi
+      .spyOn(backend as any, 'impact')
+      .mockResolvedValue({ status: 'normalized' });
+
+    await backend.callTool('impact', {
+      target: 'validate',
+      name: ' validate ',
+      symbol: 'validate',
+      direction: 'upstream',
+    });
+
+    expect(impactSpy.mock.calls[0][1]).toMatchObject({ target: 'validate' });
+  });
+
+  it.each([
+    ['impact', { target: 'validate', name: 'login', direction: 'upstream' }],
+    ['impact', { name: 'validate', symbol: 'login', direction: 'upstream' }],
+    ['context', { name: 'validate', file_path: 'src/auth.ts', file: 'src/login.ts' }],
+  ])('rejects conflicting %s aliases before repository resolution', async (method, params) => {
+    const resolveSpy = vi.spyOn(backend, 'resolveRepo');
+
+    const result = await backend.callTool(method, params);
+
+    expect(result.error).toMatch(/conflicting mcp parameters/i);
+    expect(resolveSpy).not.toHaveBeenCalled();
+  });
+
+  it.each([
+    ['impact', { target: '', direction: 'upstream' }],
+    ['impact', { name: 42, direction: 'upstream' }],
+    ['context', { name: 'validate', file: '   ' }],
+    ['context', { name: 'validate', file: null }],
+  ])('rejects invalid %s aliases before repository resolution', async (method, params) => {
+    const resolveSpy = vi.spyOn(backend, 'resolveRepo');
+
+    const result = await backend.callTool(method, params);
+
+    expect(result.error).toMatch(/non-empty string/i);
+    expect(resolveSpy).not.toHaveBeenCalled();
+  });
+
+  it('rejects a missing impact target before repository resolution', async () => {
+    const resolveSpy = vi.spyOn(backend, 'resolveRepo');
+
+    const result = await backend.callTool('impact', { direction: 'upstream' });
+
+    expect(result.error).toMatch(/requires target, name, symbol, or target_uid/i);
+    expect(resolveSpy).not.toHaveBeenCalled();
+  });
+
+  it('preserves target_uid-only impact dispatch', async () => {
+    const impactSpy = vi
+      .spyOn(backend as any, 'impact')
+      .mockResolvedValue({ status: 'normalized' });
+
+    await backend.callTool('impact', {
+      target_uid: 'Function:src/auth.ts:validate',
+      direction: 'upstream',
+    });
+
+    expect(impactSpy.mock.calls[0][1]).toMatchObject({
+      target_uid: 'Function:src/auth.ts:validate',
+    });
+  });
+
+  it('normalizes impact aliases before @group forwarding', async () => {
+    resolveAtMemberMock.mockResolvedValue({ ok: true, repoPath: '/tmp/test-project' });
+    const groupImpactSpy = vi
+      .spyOn(backend.getGroupService(), 'groupImpact')
+      .mockResolvedValue({ status: 'normalized' } as any);
+
+    await backend.callTool('impact', {
+      symbol: 'validate',
+      direction: 'upstream',
+      repo: '@grp',
+    });
+
+    expect(groupImpactSpy.mock.calls[0][0]).toMatchObject({ target: 'validate' });
+  });
+
   it('dispatches query tool', async () => {
     (executeParameterized as any).mockResolvedValue([]);
     const result = await backend.callTool('query', { query: 'auth' });

gitnexus/test/unit/tools.test.ts

@@ -128,6 +128,12 @@ describe('GITNEXUS_TOOLS', () => {
     expect(contextTool.inputSchema.required).toEqual([]);
   });
 
+  it('context tool advertises file as a compatibility alias for file_path', () => {
+    const contextTool = GITNEXUS_TOOLS.find((t) => t.name === 'context')!;
+    expect(contextTool.inputSchema.properties.file_path).toBeDefined();
+    expect(contextTool.inputSchema.properties.file).toMatchObject({ type: 'string' });
+  });
+
   it('api_impact tool expresses the route-or-file requirement via anyOf (#2308)', () => {
     const apiImpactTool = GITNEXUS_TOOLS.find((t) => t.name === 'api_impact')!;
     expect(apiImpactTool.inputSchema.anyOf).toEqual([
@@ -138,10 +144,15 @@ describe('GITNEXUS_TOOLS', () => {
     expect(apiImpactTool.inputSchema.required).toEqual([]);
   });
 
-  it('impact tool requires target and direction', () => {
+  it('impact tool requires direction and advertises target, name, or symbol without combinators', () => {
     const impactTool = GITNEXUS_TOOLS.find((t) => t.name === 'impact')!;
-    expect(impactTool.inputSchema.required).toContain('target');
     expect(impactTool.inputSchema.required).toContain('direction');
+    expect(impactTool.inputSchema.required).not.toContain('target');
+    expect(impactTool.inputSchema.properties.name).toMatchObject({ type: 'string' });
+    expect(impactTool.inputSchema.properties.symbol).toMatchObject({ type: 'string' });
+    expect(impactTool.inputSchema).not.toHaveProperty('anyOf');
+    expect(impactTool.inputSchema).not.toHaveProperty('oneOf');
+    expect(impactTool.inputSchema).not.toHaveProperty('allOf');
   });
 
   it('impact tool advertises the PDG-only `line` statement anchor (integer, min 0, not required)', () => {