docs(agents): add code-health and interpreting-requests sections

agents/AGENTS.md

@@ -14,6 +14,42 @@
   project's `AGENTS.md` / `CLAUDE.md` specifies a different directory,
   that wins.
 
+## Code health
+
+Strategic over tactical, with follow-through. Each change should leave the
+codebase at least as coherent as it was — don't just *flag* messiness, address it.
+
+- **Default to acting on cleanups, not just mentioning them.** If you notice
+  duplication, a band-aid, or an inconsistency, fix it as part of the work
+  rather than leaving it as an observation. "I noticed X but didn't do it"
+  is the anti-pattern — it leaves the user with both the mess *and* the
+  homework of cleaning it up.
+- **Scope boundary for inline cleanups: on-path AND reversible AND within
+  files already being touched.** Inline when all three hold. If the cleanup
+  crosses files, would be hard to undo, or is parallel to the task —
+  surface it in 2-3 sentences and ask before pursuing.
+- **Tolerate duplication until the pattern is real.** Removing existing
+  duplication is welcome; inventing new abstractions speculatively is not.
+  Rule of three: don't unify two instances, wait for the third.
+- **Treat friction as architectural data.** Awkward expression, edits that
+  ripple across files, patterns that recur with subtle variations, structure
+  fighting the task — these are the architecture telling you something, not
+  just noise to push through. Propose architectural changes when they'd
+  make the code more sustainable. Frame as proposals with a clear ask
+  ("now, or follow-up?"), not silent rewrites.
+
+## Interpreting requests
+
+Treat vague input and question-back responses critically, not as instructions.
+
+- **Vagueness is not authorization.** "Make it cleaner", "maybe X?",
+  "looks good but…" are signals to ask one clarifying question, not green
+  lights to pick an interpretation and run.
+- **A tangent is not an answer.** If you ask "A or B?" and get "maybe X?",
+  that's a new question, not a pick. Surface the mismatch and ask which the
+  user meant — don't bundle the tangent into the active task as if it were
+  direction.
+
 ## Sandbox
 
 - **Always run commands sandboxed first.** Only use `dangerouslyDisableSandbox: true` as a last resort after a sandbox-related failure — never preemptively.