fetch-pack: derive tunable worker defaults for URI packs

.github/workflows/codex-pgo-training.sh

@@ -0,0 +1,60 @@
+#!/bin/sh
+
+# Keep this workload short and biased toward the local Git operations Codex
+# invokes frequently. The full Git test suite is too slow for each release
+# target and would weight test-harness paths more heavily than status, diff,
+# clone, fetch, and repository maintenance.
+
+set -eu
+
+git_bin="$PWD/bin-wrappers/git"
+training_dir=$(mktemp -d "${TMPDIR:-/tmp}/codex-git-pgo.XXXXXX")
+repo="$training_dir/repo"
+clone="$training_dir/clone"
+
+cleanup () {
+	rm -rf "$training_dir"
+}
+trap cleanup EXIT HUP INT TERM
+
+mkdir -p "$training_dir/home"
+export HOME="$training_dir/home"
+export GIT_CONFIG_NOSYSTEM=1
+export GIT_TERMINAL_PROMPT=0
+
+"$git_bin" clone --quiet --no-local "$PWD" "$repo"
+"$git_bin" -C "$repo" config user.name "Codex Git PGO"
+"$git_bin" -C "$repo" config user.email "codex-git-pgo@openai.com"
+
+i=0
+while test "$i" -lt 256
+do
+	dir="$repo/training/$((i % 16))"
+	mkdir -p "$dir"
+	printf '%s\n' "$i" >"$dir/file-$i"
+	i=$((i + 1))
+done
+
+"$git_bin" -C "$repo" status --porcelain=v2 --branch >/dev/null
+"$git_bin" -C "$repo" status --porcelain=v2 --branch --untracked-files=all >/dev/null
+"$git_bin" -C "$repo" ls-files --others --exclude-standard >/dev/null
+"$git_bin" -C "$repo" add training
+"$git_bin" -C "$repo" diff --cached --stat >/dev/null
+"$git_bin" -C "$repo" commit --quiet -m "add training files"
+
+printf 'changed\n' >>"$repo/training/0/file-0"
+rm "$repo/training/1/file-1"
+mkdir -p "$repo/untracked"
+printf 'new\n' >"$repo/untracked/file"
+
+"$git_bin" -C "$repo" status --porcelain=v2 --branch >/dev/null
+"$git_bin" -C "$repo" diff --stat >/dev/null
+"$git_bin" -C "$repo" diff --name-status >/dev/null
+"$git_bin" -C "$repo" ls-files --stage >/dev/null
+"$git_bin" -C "$repo" log --oneline --decorate -20 >/dev/null
+"$git_bin" -C "$repo" rev-list --objects --all >/dev/null
+"$git_bin" -C "$repo" for-each-ref --format='%(refname) %(objectname)' >/dev/null
+"$git_bin" -C "$repo" repack -ad
+"$git_bin" clone --quiet --no-local "$repo" "$clone"
+"$git_bin" -C "$clone" status --porcelain=v2 --branch >/dev/null
+"$git_bin" -C "$clone" fetch --quiet "$repo"