Editor: Vega-Lite expression intelligence; single-home render errors

.claude/skills/alignment/SKILL.md

@@ -12,7 +12,7 @@ project's spec (`docs/spec/`) and architecture playbook (`docs/architecture/`).
 This skill is also executed by a **clean-context subagent** at session wrap-up (see
 CLAUDE.md → Session wrap-up protocol). When running as that subagent: you deliberately
 have no session context — judge the diff against the written contracts only, and return
-the summary (rule #15) as your final message so the session agent can relay it. If a
+the summary (rule #18) as your final message so the session agent can relay it. If a
 change looks deliberate but its rationale is recorded nowhere, that absence is itself a
 finding.
 
@@ -178,9 +178,16 @@ role`) or the rule it demonstrates. - **Positional sub-section cross-refs.** Cit
     (whole-spec drag/simplify) — never re-inlining the model/parse/writeBack prologue. The
     family has grown by copy-paste twice (eng-council; arch 08).
 
+17. **Spec tracks the surfaces it mandates** (`docs/spec/`): a diff that **removes, moves, or
+    renames a user-facing surface** — where a message, control, or affordance lives — updates the
+    `docs/spec/` section describing it, not only the `docs/architecture/` pattern doc. The spec is
+    the behavioral contract; an arch-doc-only update leaves it describing a surface that no longer
+    exists. An arch-only update once left spec §03E mandating an editor-pane error message after it
+    had moved to the preview (eng-council).
+
 ### Output
 
-17. **Summary**: respond with a summary of changes — choices made due to these instructions,
+18. **Summary**: respond with a summary of changes — choices made due to these instructions,
     choices where multiple approaches existed, and non-obvious architectural assumptions the
     user should know but might not spot in the diff. If the summary mentions an observation you
     chose not to fix (rule #8), confirm a `// TODO:` breadcrumb was placed at the code site.