A component can name the files its build reads elsewhere

Freshness compared the commits under a component's own cwd, which is
right about where its files are and wrong about what its build reads.
tdep-survey's two clients each source one shared scripts/android-sdk-env.sh:
a fix committed there changed what every build does, moved no component's
subtree head, rebuilt nothing, and left every card correctly reporting
"current" while answering a narrower question than the reader was asking.

alsoWatch names the rest. The paths join the component's own in the same
subtree-head and dirty comparisons -- git takes several pathspecs, so it
stays one call each -- and it is part of the acceptance gate like any
other declared field. Declared rather than inferred: which files a build
reads is not knowable from here, and both wrong guesses are expensive.

Raised by the tdep-survey session, which traced why its dioxus client
could never become stale on the serving host.

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

AGENTS.md

@@ -240,6 +240,21 @@ mutable at runtime from the phone.
   somebody asked. Stop and Uninstall do go
   through the script, and do strand the phone; the app confirms them
   rather than hiding them.
+- **A component's freshness covers its own directory plus whatever it
+  declared with `alsoWatch`** (`Component::watched_paths`, handed to
+  `git::subtree_head` and `subtree_dirty` as pathspecs -- git takes
+  several, so it stays one call). Scoping to `cwd` is right about where a
+  component's files are and wrong about what its build reads: tdep-survey's
+  two clients each source one shared `scripts/android-sdk-env.sh`, so a fix
+  committed there changed what every build does, moved no component's
+  subtree head, rebuilt nothing, and left every card correctly reporting
+  "current" -- the narrower-question shape, where nothing is wrong and
+  nothing says so. Declared rather than inferred because which files a
+  build reads is not knowable from here, and both wrong guesses are
+  expensive: too wide rebuilds everything on every commit, too narrow is
+  that silence. It is part of the acceptance gate like every other
+  declared field -- `same_declaration` destructures exhaustively, which is
+  what forced the decision when the field was added.
 - **A stripped copy is only serveable if it is signed by the key the
   build was.** `strip.rs` re-signs with `~/.android/debug.keystore`, and
   nothing about a debug keystore says which builds it made -- it is per