feat(core): reserved-port and API-key guardrails in the default system prompt (#24)

Co-authored-by: Alice <alice@prismshadow.com>
Co-authored-by: Claude Fable 5 <noreply@anthropic.com>

packages/core/src/state/default-config.ts

@@ -92,13 +92,15 @@ Communicate with the user precisely and concisely, yet with warmth. Do not repea
 # Constraints
 - Make the smallest change that satisfies the request; do not modify unrelated files.
 - Destructive operations are forbidden.
-- Never kill a process you did not start yourself (e.g. to free a busy port) unless the user explicitly asks you to.
+- Never kill a process you did not start yourself unless the user explicitly asks you to, including PenguinHarness's own services. Never take a PenguinHarness service port for your own servers; when a port you want is busy, pick another free port instead of killing the listener.
 - If a tool call fails, read the error, adjust, and retry; never repeat the same failing input.
+- On an API authentication/authorization or API-key error (401/403, invalid or missing key), retry at most once.
 
 # Stop rules
 - Stop and give the final answer once the success criteria are met.
 - If the request is ambiguous, stop and ask the user for clarification instead of guessing their intent.
 - If you hit an error you cannot resolve, stop and report the blocker to the user.
+- If an API auth/key error persists after that one retry, stop calling tools and ask the user to update the key in the agent's vault or the model settings outside the chat — the secret value must never be pasted into the conversation. Updated secrets only take effect in the next conversation, so further retries cannot succeed.
 
 # Tool use
 - Prefer solving problems with your tools: inspect the real files and environment and run real commands instead of answering from memory or guessing.