feat(orchestrator): confine task agents to the project directory

Strengthen TASK_BASICS: never read/list/search outside the project dir (OS,
other projects, global package caches), and if a task seems to need something
outside it, skip + note in the handoff rather than hunt the filesystem. Stops
the cross-filesystem exploration seen in the error-tracking/build agents.
Enforcement (canUseTool) is a follow-up.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

Author: gewenyu99

src/lib/agent/agent-prompt-loader.ts

@@ -55,7 +55,7 @@ function commandmentsReference(ctx: OrchestratorPromptContext): string | null {
   return `Framework rules for this integration are at \`${ctx.commandmentsPath}\`. Read them before you edit and follow them.`;
 }
 
-const TASK_BASICS = `You are one isolated task in a larger PostHog workflow, run as a fresh agent with no memory of the other tasks beyond the context you are given. Do only your task, then report exactly once by calling complete_task with a structured handoff: what your goal was, what you did, and what the next agent should know. When you are given context from previous steps, trust it — those agents already did their work, so do not re-verify or re-read what their handoffs tell you. Build on it and move fast. Read a file before you edit it, so your own changes do not duplicate what is already there. Work only within this project's own directory; nothing outside it is part of your task. If your task does not apply to this project — there is genuinely nothing for it to do — report it with status \`skipped\` and say why, rather than marking it done.`;
+const TASK_BASICS = `You are one isolated task in a larger PostHog workflow, run as a fresh agent with no memory of the other tasks beyond the context you are given. Do only your task, then report exactly once by calling complete_task with a structured handoff: what your goal was, what you did, and what the next agent should know. When you are given context from previous steps, trust it — those agents already did their work, so do not re-verify or re-read what their handoffs tell you. Build on it and move fast. Read a file before you edit it, so your own changes do not duplicate what is already there. Work only inside this project's own directory: never read, list, or search (find, ls, grep, glob) outside it — not the OS, not other projects, not global package caches. If your task seems to need something outside this directory, it does not — skip that part and say so in your handoff rather than hunting across the filesystem. If your task does not apply to this project — there is genuinely nothing for it to do — report it with status \`skipped\` and say why, rather than marking it done.`;
 
 const SEED_BASICS = `You are the orchestrator. Plan the work and seed the queue with enqueue_task — each call returns an id you can pass as a dependency to a later task. Give each task a short label for the UI — the action in a few words, not file names, class names, or other specifics. You are not a task yourself: do not call complete_task and do not edit the project.`;