Improve ghostwriter output language guidance (#248)

docs-site/docs/features/ghostwriter.md

@@ -27,6 +27,7 @@ Typical use cases:
 - cover letter and outreach drafts
 - interview prep tied to the job description
 - rephrasing with tone constraints
+- multilingual drafting when you want replies in a specific language
 
 ## How to use it
 
@@ -44,6 +45,10 @@ Global settings affecting generations:
 - `Constraints`
 - `Do-not-use terms`
 
+Ghostwriter follows the output language you request in your prompt. For example, `Ecris en français` should produce a French reply.
+
+If you want a persistent default language, put it in `Constraints`, for example: `Always respond in French.`
+
 `Do-not-use terms` are passed as guidance in the prompt. They are not enforced by a hard post-generation filter, so the model should avoid them but may still use them occasionally.
 
 Defaults:
@@ -80,6 +85,7 @@ Compatibility thread endpoints remain, but UI behavior is one thread per job.
 
 - Check model/provider configuration in Settings.
 - Tighten prompts with explicit output intent (for example, "3 bullet points for recruiter outreach").
+- If you need a non-English response every time, add that language requirement to `Constraints`.
 
 ### Missing context in answers
 

docs-site/docs/features/settings.md

@@ -73,6 +73,7 @@ Settings gives you runtime overrides for the key parts of discovery, scoring, ta
   - Constraints
   - Do-not-use terms
 - These settings apply to Ghostwriter and resume tailoring
+- `Constraints` can also set a default output language, for example `Always respond in French.`
 - Do-not-use terms are model guidance, not a guaranteed output filter
 
 ### Reactive Resume

orchestrator/src/server/services/ghostwriter-context.test.ts

@@ -80,6 +80,15 @@ describe("buildJobChatPromptContext", () => {
     });
     expect(context.systemPrompt).toContain("Writing style tone: direct.");
     expect(context.systemPrompt).toContain("Writing style formality: high.");
+    expect(context.systemPrompt).toContain(
+      "Follow the user's requested output language exactly when they specify one.",
+    );
+    expect(context.systemPrompt).toContain(
+      "If the global writing constraints specify an output language, follow that when the user has not requested a different language.",
+    );
+    expect(context.systemPrompt).toContain(
+      "If no output language is specified elsewhere, reply in the same language as the most recent user message.",
+    );
     expect(context.systemPrompt).toContain(
       "Writing constraints: Keep responses under 120 words",
     );
@@ -104,6 +113,24 @@ describe("buildJobChatPromptContext", () => {
     expect(context.systemPrompt).toContain("Writing style tone: professional.");
   });
 
+  it("preserves language instructions inside global writing constraints", async () => {
+    const job = createJob({ id: "job-ctx-3" });
+    vi.mocked(getJobById).mockResolvedValue(job);
+    vi.mocked(getWritingStyle).mockResolvedValue({
+      tone: "professional",
+      formality: "medium",
+      constraints: "Always respond in French.",
+      doNotUse: "",
+    });
+    vi.mocked(getProfile).mockResolvedValue({});
+
+    const context = await buildJobChatPromptContext(job.id);
+
+    expect(context.systemPrompt).toContain(
+      "Writing constraints: Always respond in French.",
+    );
+  });
+
   it("throws not found for unknown job", async () => {
     vi.mocked(getJobById).mockResolvedValue(null);
 

orchestrator/src/server/services/ghostwriter-context.ts

@@ -103,6 +103,9 @@ function buildSystemPrompt(style: WritingStyle): string {
     "Do not claim actions were executed. You are read-only and advisory.",
     "If details are missing, say what is missing before making assumptions.",
     "Avoid exposing private profile details that are unrelated to the user request.",
+    "Follow the user's requested output language exactly when they specify one.",
+    "If the global writing constraints specify an output language, follow that when the user has not requested a different language.",
+    "If no output language is specified elsewhere, reply in the same language as the most recent user message.",
     `Writing style tone: ${style.tone}.`,
     `Writing style formality: ${style.formality}.`,
     style.constraints ? `Writing constraints: ${style.constraints}` : null,