fix(agent): link uploaded artifacts in final responses

Generated-By: PostHog Code
Task-Id: 842d598b-48cc-4059-8fed-18a9965a71c4

Author: puemos

packages/agent/src/server/agent-server.ts

@@ -3627,7 +3627,7 @@ Optimize for the fewest shell round trips.
 
     const artifactInstructions = `
 ## Delivering non-code files (artifacts)
-When you create a non-code deliverable the user should be able to download (a report, chart, image, data file, rendered canvas), call the \`upload_artifact\` tool with its path before your final reply, then mention it. Files left in the workspace don't reach the user; uploaded ones show up in their artifact panel. Don't upload source code or repository changes — those belong in a commit or PR.`;
+When you create a non-code file the user should be able to download (such as a report, chart, image, archive, or data file), call the \`upload_artifact\` tool with its path before your final reply. In your final reply, link to the download URL returned by the tool—never link to the file's local workspace path. Files left in the workspace don't reach the user. Don't upload source code or repository changes—those belong in a commit or PR.`;
 
     const whyContextInstruction = `   - Add a brief **Why** to the body — one or two sentences capturing the reason the user asked for this change (the motivation, not a restatement of the diff). Keep it short.`;
     const publicRepoSafetyInstruction = `   - **Public-repo safety.** Treat the target repository as public-readable unless you have verified otherwise. The PR title, description, and commit messages must not contain private operational scale (exact event counts, internal row volumes, customer-usage percentages), customer names / emails / companies, references to internal tickets or incidents, the contents of Slack threads (do not quote or paraphrase what was said), or unreleased roadmap details. Linking to the originating Slack thread is fine and encouraged — Slack links are auth-gated and useful as context — as are channel references like "raised in #team-foo". Describe findings qualitatively ("present on nearly all X events, absent from Y") rather than with quantitative figures pulled from analytics queries — the reasoning that uses those numbers can stay in the thread; the PR copy cannot.`;