diff --git a/scripts/__tests__/schemas.test.js b/scripts/__tests__/schemas.test.js
index eeb965f..47a62c1 100644
--- a/scripts/__tests__/schemas.test.js
+++ b/scripts/__tests__/schemas.test.js
@@ -75,6 +75,104 @@ describe('team-member schema', () => {
   });
 });
 
+describe('team-member expert fields', () => {
+  const expert = {
+    ...validMember,
+    challenge: 'sc',
+    contribution: { fr: 'Contribution', en: 'Contribution EN' },
+    tools: ['hubspot', 'qobra'],
+    previousCompanies: ['Qonto'],
+  };
+  const fails = (data) => validateTeamMember(data).success === false;
+  const messages = (data) => validateTeamMember(data).error.issues.map((i) => i.message);
+
+  it('accepts a member without any expert field', () => {
+    expect(validateTeamMember(validMember).success).toBe(true);
+  });
+
+  it('accepts a member with all four expert fields', () => {
+    expect(validateTeamMember(expert).success).toBe(true);
+  });
+
+  it('accepts every challenge key', () => {
+    for (const challenge of ['rp', 'se', 'sc', 'cx', 'sy', 'ai']) {
+      expect(validateTeamMember({ ...expert, challenge }).success).toBe(true);
+    }
+  });
+
+  it('rejects an unknown challenge key', () => {
+    expect(fails({ ...expert, challenge: 'xx' })).toBe(true);
+  });
+
+  it('rejects challenge without contribution', () => {
+    const { contribution, ...rest } = expert;
+    expect(fails(rest)).toBe(true);
+    expect(messages(rest)).toContain('contribution is required when challenge is set');
+  });
+
+  it('rejects challenge without tools', () => {
+    const { tools, ...rest } = expert;
+    expect(fails(rest)).toBe(true);
+    expect(messages(rest)).toContain('tools is required when challenge is set');
+  });
+
+  it('accepts challenge without previousCompanies', () => {
+    const { previousCompanies, ...rest } = expert;
+    expect(validateTeamMember(rest).success).toBe(true);
+  });
+
+  it('accepts contribution, tools and previousCompanies without challenge', () => {
+    const { challenge, ...rest } = expert;
+    expect(validateTeamMember(rest).success).toBe(true);
+  });
+
+  it('caps contribution at 100 characters per language', () => {
+    const ok = 'x'.repeat(100);
+    const tooLong = 'x'.repeat(101);
+    expect(validateTeamMember({ ...expert, contribution: { fr: ok, en: ok } }).success).toBe(true);
+    expect(fails({ ...expert, contribution: { fr: tooLong, en: ok } })).toBe(true);
+    expect(fails({ ...expert, contribution: { fr: ok, en: tooLong } })).toBe(true);
+  });
+
+  it('rejects a contribution missing a language', () => {
+    expect(fails({ ...expert, contribution: { fr: 'Contribution' } })).toBe(true);
+  });
+
+  it('accepts 1 to 8 tools and rejects 0 or 9', () => {
+    const slugs = (n) => Array.from({ length: n }, (_, i) => `tool-${i}`);
+    expect(validateTeamMember({ ...expert, tools: slugs(1) }).success).toBe(true);
+    expect(validateTeamMember({ ...expert, tools: slugs(8) }).success).toBe(true);
+    expect(fails({ ...expert, tools: [] })).toBe(true);
+    expect(fails({ ...expert, tools: slugs(9) })).toBe(true);
+  });
+
+  it('rejects duplicate tools', () => {
+    const data = { ...expert, tools: ['hubspot', 'hubspot'] };
+    expect(fails(data)).toBe(true);
+    expect(messages(data)).toContain('tools must not contain duplicates');
+  });
+
+  it('rejects a blank contribution or previous company', () => {
+    expect(fails({ ...expert, contribution: { fr: '   ', en: 'Contribution' } })).toBe(true);
+    expect(fails({ ...expert, previousCompanies: ['  '] })).toBe(true);
+  });
+
+  it('applies the contribution cap to the raw text', () => {
+    expect(fails({ ...expert, contribution: { fr: `${'x'.repeat(100)} `, en: 'ok' } })).toBe(true);
+  });
+
+  it('accepts 1 to 3 previous companies and rejects 0 or 4', () => {
+    expect(validateTeamMember({ ...expert, previousCompanies: ['A', 'B', 'C'] }).success).toBe(true);
+    expect(fails({ ...expert, previousCompanies: [] })).toBe(true);
+    expect(fails({ ...expert, previousCompanies: ['A', 'B', 'C', 'D'] })).toBe(true);
+  });
+
+  it('caps a previous company name at 30 characters', () => {
+    expect(validateTeamMember({ ...expert, previousCompanies: ['x'.repeat(30)] }).success).toBe(true);
+    expect(fails({ ...expert, previousCompanies: ['x'.repeat(31)] })).toBe(true);
+  });
+});
+
 // ── blog post ─────────────────────────────────────────────────────────────────
 
 const validPost = {
diff --git a/scripts/__tests__/validate-repository.test.js b/scripts/__tests__/validate-repository.test.js
index 488eb45..a3b511f 100644
--- a/scripts/__tests__/validate-repository.test.js
+++ b/scripts/__tests__/validate-repository.test.js
@@ -98,6 +98,56 @@ describe('validateRepository', () => {
     expect(assetErrors).toEqual([expect.stringContaining('assets/clients/acme-avatar.jpeg')]);
     expect(assetWarnings).toEqual([]);
   });
+
+  it('reports a team member citing a missing tool slug', () => {
+    write('team/bob.md', `${TEAM_MEMBER.replace(/---\n$/, '')}challenge: sc
+contribution:
+  fr: Contribution
+  en: Contribution
+tools:
+  - hubspot
+  - ghost-tool
+---
+`);
+
+    const { failures } = validateRepository(repoRoot);
+
+    expect(failures).toEqual([
+      {
+        file: 'team/bob.md',
+        schemaErrors: [],
+        crossRefErrors: [
+          { path: ['tools'], message: '"ghost-tool" does not match any tool slug' },
+        ],
+      },
+    ]);
+  });
+
+  it('accepts a team member whose tools are all existing tool slugs', () => {
+    write('team/bob.md', `${TEAM_MEMBER.replace(/---\n$/, '')}challenge: sc
+contribution:
+  fr: Contribution
+  en: Contribution
+tools:
+  - hubspot
+---
+`);
+
+    expect(validateRepository(repoRoot).failures).toEqual([]);
+  });
+
+  it('reports a schema error, not a crash, when tools is not an array', () => {
+    write('team/bob.md', `${TEAM_MEMBER.replace(/---\n$/, '')}tools: hubspot
+---
+`);
+
+    const { failures } = validateRepository(repoRoot);
+
+    expect(failures).toHaveLength(1);
+    expect(failures[0].file).toBe('team/bob.md');
+    expect(failures[0].schemaErrors).toEqual([{ path: ['tools'], message: expect.any(String) }]);
+    expect(failures[0].crossRefErrors).toEqual([]);
+  });
 });
 
 describe('validateRepository with challenge files', () => {
diff --git a/scripts/schemas/team-member.schema.js b/scripts/schemas/team-member.schema.js
index 44d9649..9907b9e 100644
--- a/scripts/schemas/team-member.schema.js
+++ b/scripts/schemas/team-member.schema.js
@@ -1,4 +1,5 @@
 import { z } from 'zod';
+import { CHALLENGE_KEYS } from './challenge.schema.js';
 
 const bilingualString = z.object({ fr: z.string().min(1), en: z.string().min(1) });
 
@@ -17,6 +18,29 @@ export const teamMemberSchema = z.object({
   active: z.boolean().optional(),
   featuredOnAboutUs: z.boolean().optional(),
   color: z.enum(['yellow', 'coral', 'sky']).optional(),
+  // Expert fields: all optional, absent for people who are not challenge experts.
+  challenge: z.enum(CHALLENGE_KEYS).optional(),
+  // Caps apply to the raw text, as published, so no .trim(); \S rejects blanks.
+  contribution: z.object({
+    fr: z.string().regex(/\S/).max(100),
+    en: z.string().regex(/\S/).max(100),
+  }).optional(),
+  tools: z.array(z.string().min(1)).min(1).max(8).refine(
+    (slugs) => new Set(slugs).size === slugs.length,
+    { message: 'tools must not contain duplicates' },
+  ).optional(),
+  previousCompanies: z.array(z.string().regex(/\S/).max(30)).min(1).max(3).optional(),
+}).superRefine((member, ctx) => {
+  if (member.challenge === undefined) return;
+  for (const field of ['contribution', 'tools']) {
+    if (member[field] === undefined) {
+      ctx.addIssue({
+        code: 'custom',
+        path: [field],
+        message: `${field} is required when challenge is set`,
+      });
+    }
+  }
 });
 
 export const validateTeamMember = (data) => teamMemberSchema.safeParse(data);
diff --git a/scripts/validate-repository.js b/scripts/validate-repository.js
index 3c70353..beed9e1 100644
--- a/scripts/validate-repository.js
+++ b/scripts/validate-repository.js
@@ -45,6 +45,15 @@ const validateCrossRefs = (type, data, resolver) => {
       });
     }
   }
+  if (type === 'team-member') {
+    // A non-array `tools` is already a schema error; skip the cross-reference.
+    const tools = Array.isArray(data.tools) ? data.tools.filter((t) => typeof t === 'string') : [];
+    tools.forEach((t) => {
+      if (!resolver.isValidToolSlug(t)) {
+        errors.push({ path: ['tools'], message: `"${t}" does not match any tool slug` });
+      }
+    });
+  }
   if (type === 'job' && data.hiringContact && !resolver.isValidTeamSlug(data.hiringContact)) {
     errors.push({
       path: ['hiringContact'],