Checks and tests run for the part a change is in

The pre-commit hook ran clippy on the whole workspace for any Rust change;
it now checks the crates touched and those built on them (ipx uses
ipx-directory, both use ipx-feed), and nothing for a change to the page
alone. CLAUDE.md says which tests go with which part.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

.githooks/pre-commit

@@ -1,13 +1,26 @@
 #!/bin/sh
 # Refuses a commit whose Rust is not as rustfmt writes it, or that clippy warns about. Clippy only
-# checks and never links, so it is light beside a test build (CLAUDE.md, Tests); with the line-tables
+# checks and never links, so it is light beside a test build (CLAUDE.md, Tests). It checks the
-# profile it takes about a minute after a change and seconds otherwise.
+# crates the commit touches and those built on them, not the workspace: ipx uses ipx-directory,
-git diff --cached --name-only --diff-filter=ACM | grep -q '\.rs$' || exit 0
+# and both use ipx-feed. A commit to the page alone runs nothing here.
+staged=$(git diff --cached --name-only --diff-filter=ACMD)
+echo "$staged" | grep -q -e '\.rs$' -e 'Cargo\.toml$' -e '^Cargo\.lock$' || exit 0
 if ! cargo fmt --all --check >/dev/null 2>&1; then
 	echo "pre-commit: the Rust is not formatted; run cargo fmt --all" >&2
 	exit 1
 fi
-if ! cargo clippy --workspace --all-targets -q -- -D warnings; then
+if echo "$staged" | grep -q -e '^Cargo\.toml$' -e '^Cargo\.lock$' -e '^crates/feed/'; then
-	echo "pre-commit: clippy has warnings; fix them, or allow one where it is wrong, with a comment saying why" >&2
+	pkgs="ipx-feed ipx-directory ipx"
+elif echo "$staged" | grep -q '^crates/directory/'; then
+	pkgs="ipx-directory ipx"
+elif echo "$staged" | grep -q '^crates/ipx/'; then
+	pkgs="ipx"
+else
+	exit 0
+fi
+args=$(for p in $pkgs; do printf ' -p %s' "$p"; done)
+# shellcheck disable=SC2086 # one word a flag
+if ! cargo clippy $args --all-targets -q -- -D warnings; then
+	echo "pre-commit: clippy has warnings in $pkgs; fix them, or allow one where it is wrong, with a comment saying why" >&2
 	exit 1
 fi

CLAUDE.md

@@ -198,8 +198,18 @@ session was stopped. So:
   run in the background beside another, and never two crates' builds at once. Do not tune `-j`.
 * Look at the load before and after each (`cat /proc/loadavg`). Above about 24, Tower's twelve
   threads twice over, wait for it to come down before starting another.
-* Build only the crate the change is in (`cargo build -p ipx-directory`), and run only its tests
+* Test only what the change is in. ipx uses ipx-directory, and both use ipx-feed, so:
-  until the change is done; the whole workspace's once, at the end.
+
+  | changed | run |
+  |---|---|
+  | `web/` alone | the three page checks; `npx playwright test -g '<what changed>'`; no cargo |
+  | `crates/ipx/` | `cargo test -p ipx`; the browser tests too if the API changed |
+  | `crates/directory/` | `cargo test -p ipx-directory`, then `-p ipx` |
+  | `crates/feed/` | `cargo test -p ipx-feed`, then `-p ipx-directory`, then `-p ipx` |
+  | `Cargo.toml`, `Cargo.lock` | all three, one at a time |
+
+  The pre-commit hook's clippy follows the same table. The whole browser suite once, at the end
+  of a change to the page or the API; never `cargo test` for the workspace in one command.
 * Builds and test binaries live under `target/`, a link to `/mnt/fast`; linking through
   `/mnt/user` (FUSE) once took the load to 248 on its own.
 * **Memory is the tighter limit.** Tower has 31 GB, no swap, and the containers leave about 4-7