diff --git a/bench/check.sh b/bench/check.sh
new file mode 100755
index 00000000..134556de
--- /dev/null
+++ b/bench/check.sh
@@ -0,0 +1,27 @@
+#!/usr/bin/env bash
+# The final type-check, lint and tests of one run, from a clean worktree of its head: a fresh
+# install with lifecycle scripts off, then the repository's own commands from selection.json.
+#
+#   BENCH_OUT=<dir> bench/check.sh <run>
+set -euo pipefail
+run=$1
+here=$(cd "$(dirname "$0")" && pwd)
+dir=${BENCH_OUT:?}/runs/$run
+id=$(jq -r .id "$dir/meta.json") head=$(jq -r .head "$dir/meta.json")
+export npm_config_ignore_scripts=true YARN_ENABLE_SCRIPTS=0 CI=1
+rm -rf "$dir/check"
+git -C "$dir/repo" worktree prune
+git -C "$dir/repo" worktree add -q --detach "$dir/check" "$head"
+cd "$dir/check"
+result='{}'
+for step in install typecheck lint test; do
+  cmd=$(jq -r --arg id "$id" --arg s "$step" '.repos[] | select(.id == $id) | .checks[$s] // ""' "$here/selection.json")
+  [ -z "$cmd" ] && continue
+  code=0
+  bash -c "$cmd" >"$dir/check-$step.log" 2>&1 || code=$?
+  result=$(jq --arg s "$step" --argjson c "$code" '.[$s] = $c' <<<"$result")
+  # Nothing else means anything without dependencies.
+  [ "$step" = install ] && [ "$code" != 0 ] && break
+done
+echo "$result" >"$dir/checks.json"
+echo "$run $result"
diff --git a/bench/claude-sandbox.json b/bench/claude-sandbox.json
new file mode 100644
index 00000000..99146156
--- /dev/null
+++ b/bench/claude-sandbox.json
@@ -0,0 +1,27 @@
+{
+  "sandbox": {
+    "enabled": true,
+    "failIfUnavailable": true,
+    "allowUnsandboxedCommands": false,
+    "autoAllowBashIfSandboxed": true,
+    "filesystem": {
+      "allowWrite": ["~/.npm", "~/Library/pnpm", "~/Library/Caches", "~/.cache"]
+    },
+    "network": {
+      "allowedDomains": [
+        "registry.npmjs.org",
+        "registry.yarnpkg.com",
+        "repo.yarnpkg.com",
+        "github.com",
+        "codeload.github.com",
+        "objects.githubusercontent.com"
+      ],
+      "strictAllowlist": true,
+      "allowLocalBinding": true
+    }
+  },
+  "permissions": {
+    "deny": ["Bash(dangerouslyDisableSandbox:true)", "WebFetch", "WebSearch"],
+    "allow": ["Bash"]
+  }
+}
diff --git a/bench/excluded.json b/bench/excluded.json
new file mode 100644
index 00000000..607a52d8
--- /dev/null
+++ b/bench/excluded.json
@@ -0,0 +1,443 @@
+[
+  {
+    "pack": "react-router",
+    "repo": "Arize-ai/phoenix",
+    "commit": "4d6c1dfb01e9406cf769efab14f0350ea2d0a0f8",
+    "from": "6.25.1",
+    "to": "7.4.0"
+  },
+  {
+    "pack": "stripe",
+    "repo": "AtlasDevHQ/atlas",
+    "commit": "cfaf3c3c500995a4dc1e918ef89de20e535af43f",
+    "from": "21.0.1",
+    "to": "22.2.0"
+  },
+  {
+    "pack": "@sentry/browser",
+    "repo": "Automancer-Ltd/automancer-site",
+    "commit": "ea78c738e8de80efbb796b506fbc81bb4f649f70",
+    "from": "10.75.2",
+    "to": "11.4.0"
+  },
+  {
+    "pack": "typescript",
+    "repo": "Borewit/music-metadata",
+    "commit": "783509b27bac24e244dd75e66c9b4a0828c35a96",
+    "from": "5.9.3",
+    "to": "6.0.3"
+  },
+  {
+    "pack": "zod",
+    "repo": "CANShift/canshift-core",
+    "commit": "3ad0a35edd902e94cb3014f1331cd38528532e3f",
+    "from": "3.25.76",
+    "to": "4.4.3"
+  },
+  {
+    "pack": "typescript",
+    "repo": "CroffZ/github-release-notifier",
+    "commit": "d9353f2471c554f0ce339496f0058a27599f4965",
+    "from": "5.9.3",
+    "to": "6.0.3"
+  },
+  {
+    "pack": "next",
+    "repo": "HiroshiIgarash/koremina",
+    "commit": "e9a1595083f746c8cb481e1ca7156aca6db6d4d0",
+    "from": "15.5.10",
+    "to": "16.1.6"
+  },
+  {
+    "pack": "typescript",
+    "repo": "JosephMaynard/dependency-radar",
+    "commit": "1920eb3217b701e43afc1651db3f6197028e6f0e",
+    "from": "5.9.3",
+    "to": "6.0.3"
+  },
+  {
+    "pack": "typescript",
+    "repo": "SignalK/signalk-derived-data",
+    "commit": "02f635e8232a433462593ed1192ff22e2e9b6253",
+    "from": "5.9.3",
+    "to": "6.0.3"
+  },
+  {
+    "pack": "@sentry/node",
+    "repo": "TryGhost/ActivityPub",
+    "commit": "f8a8233219f927b39a41418c7cce0f2fa4867b67",
+    "from": "10.75.3",
+    "to": "11.0.0"
+  },
+  {
+    "pack": "redis",
+    "repo": "UNN-Devotek/FCM-Fallout-Chat-Mod",
+    "commit": "280190489fac1ac8b75bf5fda8fd54265f339d7e",
+    "from": "4.7.1",
+    "to": "6.0.0"
+  },
+  {
+    "pack": "express",
+    "repo": "amiantos/lurker",
+    "commit": "f7a0f3dac77570ec3fd93a487ccf0aaf2f6ca5db",
+    "from": "4.22.2",
+    "to": "5.2.1"
+  },
+  {
+    "pack": "zod",
+    "repo": "band-ai/band-sdk-typescript",
+    "commit": "5d9a66a1dde4989fbc0608200f291f0ca8194052",
+    "from": "3.25.76",
+    "to": "4.6.5"
+  },
+  {
+    "pack": "express",
+    "repo": "bcgov/tenant-management-system",
+    "commit": "6fd01755043a3db9ed0577ffa6b1b4a184ae670f",
+    "from": "4.22.2",
+    "to": "5.2.1"
+  },
+  {
+    "pack": "next",
+    "repo": "benshabbat/GamesForMyKids",
+    "commit": "793cb46f19f2bc279dbf741a74cf7083a5025310",
+    "from": "15.5.15",
+    "to": "16.2.6"
+  },
+  {
+    "pack": "@sentry/nextjs",
+    "repo": "cohstats/coh3-stats",
+    "commit": "5b9c60bd6575ed4a4bcd8d2bb71529766675a7e6",
+    "from": "10.75.3",
+    "to": "11.1.0"
+  },
+  {
+    "pack": "openai",
+    "repo": "csnyder256/ux-struggle-detector",
+    "commit": "b73084896208f7d2794b84bf23de3157eca5fc09",
+    "from": "4.104.0",
+    "to": "7.23.0"
+  },
+  {
+    "pack": "lucide-react",
+    "repo": "cubicsteak/keep",
+    "commit": "9380d10ea22b66e4559779d7cc3afb4f209cf198",
+    "from": "0.483.0",
+    "to": "1.47.0"
+  },
+  {
+    "pack": "redis",
+    "repo": "deanmoses/tacocat-gallery-sam",
+    "commit": "34e11760f6e767abef6afd53f973dc155f6f8c4b",
+    "from": "4.6.12",
+    "to": "5.10.0"
+  },
+  {
+    "pack": "redis",
+    "repo": "deanmoses/tacocat-gallery-sam",
+    "commit": "30724e21efd6db123a7385e73482cac237b1e9ba",
+    "from": "5.12.1",
+    "to": "6.2.1"
+  },
+  {
+    "pack": "openai",
+    "repo": "digitalchokro/askchokro",
+    "commit": "047fc4485538a3bff4224a9a604d83143c2cd5d2",
+    "from": "4.104.0",
+    "to": "7.4.0"
+  },
+  {
+    "pack": "joi",
+    "repo": "edtech4good/edtech-lms-api",
+    "commit": "ce2281005fcf0c41a883779c778f3123a48bbeec",
+    "from": "17.6.0",
+    "to": "18.2.9"
+  },
+  {
+    "pack": "react",
+    "repo": "excalidraw/excalidraw",
+    "commit": "9ee0b8ffcbd3664a47748a93262860321a203821",
+    "from": "18.2.0",
+    "to": "19.0.0"
+  },
+  {
+    "pack": "ioredis",
+    "repo": "ferni-ai/voiceai",
+    "commit": "c59ed0982f96e23d2b2f5728711da5b55e07483a",
+    "from": "5.8.2",
+    "to": "6.0.0"
+  },
+  {
+    "pack": "@sentry/node",
+    "repo": "frog-pond/ccc-server",
+    "commit": "75fdc083bbf719c5c577b4c3068528776bea6fa3",
+    "from": "10.75.3",
+    "to": "11.2.0"
+  },
+  {
+    "pack": "react-router",
+    "repo": "getlago/lago-front",
+    "commit": "84aa05d535edc326a4d104923e4e7293d1be6646",
+    "from": "6.30.6",
+    "to": "7.18.3"
+  },
+  {
+    "pack": "openai",
+    "repo": "grantsingleton/batch-ai",
+    "commit": "05c7e9f132b3e6ec6504de3d82371889fdc2d368",
+    "from": "4.83.0",
+    "to": "7.4.0"
+  },
+  {
+    "pack": "zod",
+    "repo": "howardyang2009/PATH",
+    "commit": "bb171417d911f373c8df28ab7a1e0698b62e0906",
+    "from": "3.25.76",
+    "to": "4.6.5"
+  },
+  {
+    "pack": "ioredis",
+    "repo": "kazumadev619-dev/FishingConditionsApp",
+    "commit": "8ba3f0d24bc709169b79df11daa87307df32e77c",
+    "from": "5.11.1",
+    "to": "6.0.0"
+  },
+  {
+    "pack": "typescript",
+    "repo": "m-lyon/recipe",
+    "commit": "f6e44b530c4dab5afc9ca6f3505774d5b44fcd33",
+    "from": "5.6.2",
+    "to": "6.0.3"
+  },
+  {
+    "pack": "@sentry/nextjs",
+    "repo": "maximunited/yomu",
+    "commit": "228fc3e4f7abf1850e4d03d32535e28b5173306c",
+    "from": "10.75.1",
+    "to": "11.1.0"
+  },
+  {
+    "pack": "openai",
+    "repo": "microsoft/prompty",
+    "commit": "e878b6b7789ff621265ca086b20d4e2d70914f81",
+    "from": "4.104.0",
+    "to": "7.10.0"
+  },
+  {
+    "pack": "ai",
+    "repo": "miurla/morphic",
+    "commit": "989a05697d973030f2fbb4b805326bb24e68fd0d",
+    "from": "6.0.180",
+    "to": "7.0.66"
+  },
+  {
+    "pack": "express",
+    "repo": "netlify/cli",
+    "commit": "63b6f1cbca316fa6c338d59e5b5053a11de25c6c",
+    "from": "4.22.1",
+    "to": "5.2.1"
+  },
+  {
+    "pack": "stripe",
+    "repo": "nextjs/saas-starter",
+    "commit": "3e5fd2bf626c4ee73c06dcc9e1aa503b8904a37c",
+    "from": "17.7.0",
+    "to": "18.0.0"
+  },
+  {
+    "pack": "openai",
+    "repo": "openai/openai-guardrails-js",
+    "commit": "6c13ba08ab021215fd6f8c900ae15ae29627f2d2",
+    "from": "4.104.0",
+    "to": "7.9.0"
+  },
+  {
+    "pack": "express",
+    "repo": "openhab/openhab-cloud",
+    "commit": "5a1866efe1c038e287d2d59091951e1912db12f8",
+    "from": "4.22.1",
+    "to": "5.2.1"
+  },
+  {
+    "pack": "@sentry/react",
+    "repo": "owine/youth-activity-scheduler",
+    "commit": "18b467f5c4f2fc066e14dc5edfe10874016ba3d3",
+    "from": "10.75.3",
+    "to": "11.0.0"
+  },
+  {
+    "pack": "typescript",
+    "repo": "robrechtme/recipes",
+    "commit": "0853747427b71f1d5de275e72aead59979fc1a03",
+    "from": "5.9.3",
+    "to": "6.0.3"
+  },
+  {
+    "pack": "ioredis",
+    "repo": "safe-global/safe-client-gateway",
+    "commit": "14bd05b98bf41df509de0bfee8bc662cb9d95d1e",
+    "from": "5.11.1",
+    "to": "6.0.0"
+  },
+  {
+    "pack": "next",
+    "repo": "sambecker/exif-photo-blog",
+    "commit": "3f1a36354d203e5a28f7c2cd55eceda95a13e3bd",
+    "from": "15.5.5",
+    "to": "16.0.1"
+  },
+  {
+    "pack": "@sentry/browser",
+    "repo": "sbomify/sbomify",
+    "commit": "4c2be20126779d91d629b9478c6a0aff0239abfe",
+    "from": "10.75.2",
+    "to": "11.0.0"
+  },
+  {
+    "pack": "joi",
+    "repo": "senacor/azure-function-middleware",
+    "commit": "5c2da676e7327681dde70db6229edeebfa76b0f4",
+    "from": "17.13.1",
+    "to": "18.0.1"
+  },
+  {
+    "pack": "typescript",
+    "repo": "shogo82148/typescript-action",
+    "commit": "0f03405c7267fafaebee5d57e773c1bb56e28b44",
+    "from": "5.9.3",
+    "to": "6.0.3"
+  },
+  {
+    "pack": "ioredis",
+    "repo": "simondietschi/dokunc",
+    "commit": "83681ed0ccc527fa1dd5c802f554f26a5eac575c",
+    "from": "5.11.1",
+    "to": "6.0.0"
+  },
+  {
+    "pack": "lucide-react",
+    "repo": "spizeck/SFPCA",
+    "commit": "7f5b9dcb8985260e7b9ab345be971b392bd129a5",
+    "from": "0.563.0",
+    "to": "1.47.0"
+  },
+  {
+    "pack": "stripe",
+    "repo": "starl3xx/wallet-to-social",
+    "commit": "b7f60f1167b4665746e455696f6aa34caa75ad0c",
+    "from": "20.2.0",
+    "to": "22.6.2"
+  },
+  {
+    "pack": "next",
+    "repo": "stoczec/wortkarte",
+    "commit": "e3bd3679ae6ea60ce2a78aefebec0caa48c4febd",
+    "from": "15.5.27",
+    "to": "16.3.8"
+  },
+  {
+    "pack": "@sentry/react",
+    "repo": "successible/cleanslate",
+    "commit": "5d45401e6562e6c028028774c9097ecb4737dc6e",
+    "from": "10.74.0",
+    "to": "11.0.0"
+  },
+  {
+    "pack": "redis",
+    "repo": "swoofer/mcp-coordinator",
+    "commit": "8b337f0a081d0d0e0c3724890b9cc847b6c5dd6f",
+    "from": "5.12.1",
+    "to": "6.2.0"
+  },
+  {
+    "pack": "ioredis",
+    "repo": "syzygyhack/open-foundry",
+    "commit": "73910018b5e8119cf4db99a81ff145726451aa3b",
+    "from": "5.10.1",
+    "to": "6.0.0"
+  },
+  {
+    "pack": "redis",
+    "repo": "tearingItUp786/blog",
+    "commit": "bb88f3afc40df07e29da461c6aed6c34709bc6bf",
+    "from": "4.7.0",
+    "to": "6.0.0"
+  },
+  {
+    "pack": "react",
+    "repo": "tldraw/tldraw",
+    "commit": "5957867a9c5c205a0b0c3665be443138b8014a79",
+    "from": "18.3.1",
+    "to": "19.2.1"
+  },
+  {
+    "pack": "lucide-react",
+    "repo": "tradeblocks-org/tradeblocks",
+    "commit": "918c0dadccacec7e0533ea1a208f252562ac711f",
+    "from": "0.577.0",
+    "to": "1.52.0"
+  },
+  {
+    "pack": "zod",
+    "repo": "ugurkocde/AwesomeIntune",
+    "commit": "dcf38603fd55cea72737e17274d5de03cece341e",
+    "from": "3.25.76",
+    "to": "4.6.5"
+  },
+  {
+    "pack": "stripe",
+    "repo": "unkeyed/unkey",
+    "commit": "37044fc57fe08c917e92b323933baf322d6df1c6",
+    "from": "14.23.0",
+    "to": "22.2.0"
+  },
+  {
+    "pack": "ai",
+    "repo": "vercel/chatbot",
+    "commit": "77d362e596e2c624638cad5a35199c0c8785c9fd",
+    "from": "6.0.116",
+    "to": "7.0.9"
+  },
+  {
+    "pack": "vitest",
+    "repo": "vitorvasc/opentelemetry-ecosystem-explorer",
+    "commit": "46d5b37d00bbf27f394e33cee64a0e206c31315f",
+    "from": "4.1.11",
+    "to": "5.0.0"
+  },
+  {
+    "pack": "vitest",
+    "repo": "votingworks/vxsuite",
+    "commit": "5cb3c7d9c1abc891e7b12de57c0278790dd6160a",
+    "from": "4.1.11",
+    "to": "5.0.2"
+  },
+  {
+    "pack": "zod",
+    "repo": "vzdc-artcc/website",
+    "commit": "48a93f65a0976e342d4c15145b51de8eef030214",
+    "from": "3.25.76",
+    "to": "4.6.5"
+  },
+  {
+    "pack": "openai",
+    "repo": "wardby/wardby",
+    "commit": "d46ec64dc0be781aa43967d9b6d26be9386aa67d",
+    "from": "4.104.0",
+    "to": "7.30.0"
+  },
+  {
+    "pack": "@sentry/nextjs",
+    "repo": "xdoubleu/tools.xdoubleu.com",
+    "commit": "d3b780d42c8937af42d37072f7b0948bced39d47",
+    "from": "10.75.3",
+    "to": "11.0.0"
+  },
+  {
+    "pack": "openai",
+    "repo": "zeikar/charivo",
+    "commit": "b9a476d9acb59f473e08f0e97ce6e91dc2201d99",
+    "from": "4.104.0",
+    "to": "7.10.0"
+  }
+]
diff --git a/bench/judge.sh b/bench/judge.sh
new file mode 100755
index 00000000..6cf8f065
--- /dev/null
+++ b/bench/judge.sh
@@ -0,0 +1,47 @@
+#!/usr/bin/env bash
+# Let the repository's own CI judge one run: a fork in the uptide-bench organization whose
+# default branch is reset to the parent commit (so `pull_request` branch filters match), the
+# run's head pushed as bench/<run>, and a pull request between the two, on the fork only.
+# Pushes go to the fork's explicit URL; the original repository is never written to.
+#
+#   BENCH_OUT=<dir> bench/judge.sh <run>            fork, push, open the pull request
+#   BENCH_OUT=<dir> bench/judge.sh <run> --collect  wait for its checks once, store them
+set -euo pipefail
+run=$1
+here=$(cd "$(dirname "$0")" && pwd)
+dir=${BENCH_OUT:?}/runs/$run
+org=uptide-bench
+id=$(jq -r .id "$dir/meta.json") head=$(jq -r .head "$dir/meta.json")
+sel() { jq -er --arg id "$id" ".repos[] | select(.id == \$id) | $1" "$here/selection.json"; }
+repo=$(sel .repo) parent=$(sel .parent)
+fork=$org/${repo%%/*}--${repo##*/}
+
+if [ "${2:-}" = --collect ]; then
+  pr=$(jq -r .number "$dir/pr.json")
+  [ "$pr" = null ] && exit 0
+  gh pr checks "$pr" --repo "$fork" --watch --interval 60 >/dev/null 2>&1 || :
+  gh pr checks "$pr" --repo "$fork" --json name,workflow,state,bucket >"$dir/ci.json" || :
+  echo "$run $(jq -c 'group_by(.bucket) | map({(.[0].bucket): length}) | add' "$dir/ci.json")"
+  exit 0
+fi
+
+if [ "$head" = "$parent" ]; then
+  echo '{"number": null, "skipped": "no commits"}' >"$dir/pr.json"
+  echo "$run no commits, no pull request"
+  exit 0
+fi
+if ! gh repo view "$fork" >/dev/null 2>&1; then
+  gh repo fork "$repo" --org "$org" --fork-name "${fork#*/}" --clone=false --default-branch-only
+  sleep 5
+fi
+# Forks start with Actions off.
+gh api -X PUT "repos/$fork/actions/permissions" -F enabled=true -f allowed_actions=all >/dev/null
+base=$(gh api "repos/$fork" --jq .default_branch)
+url=https://github.com/$fork.git
+git -C "$dir/repo" push -q --force "$url" "$parent:refs/heads/$base"
+git -C "$dir/repo" push -q --force "$url" "$head:refs/heads/bench/$run"
+head -c 60000 "$dir/summary.md" >"$dir/pr-body.md"
+[ -s "$dir/pr-body.md" ] || echo "(no summary)" >"$dir/pr-body.md"
+gh api "repos/$fork/pulls" -f title="bench $run" -f head="bench/$run" -f base="$base" \
+  -F body=@"$dir/pr-body.md" --jq '{number, url: .html_url}' >"$dir/pr.json"
+echo "$run $(cat "$dir/pr.json")"
diff --git a/bench/run.sh b/bench/run.sh
new file mode 100755
index 00000000..23fb1166
--- /dev/null
+++ b/bench/run.sh
@@ -0,0 +1,77 @@
+#!/usr/bin/env bash
+# One run of one arm on one repository of bench/selection.json.
+#
+#   BENCH_OUT=<dir outside this repo> bench/run.sh <claude|uptide|human> <id>
+#
+# Both arms start from the same fresh clone of the parent commit, with installs' lifecycle
+# scripts off and pushes to the original repository disabled. `human` checks out the human's
+# upgrade commit instead: the reference every score is measured against.
+# The run gets an opaque id; $BENCH_OUT/key.tsv is the only place its arm is written, so
+# check.sh, judge.sh and score.mjs never see it.
+set -euo pipefail
+arm=$1 id=$2
+here=$(cd "$(dirname "$0")" && pwd)
+out=${BENCH_OUT:?set BENCH_OUT to a directory outside this repository}
+sel() { jq -er --arg id "$id" ".repos[] | select(.id == \$id) | $1" "$here/selection.json"; }
+repo=$(sel .repo) parent=$(sel .parent) upgrade=$(sel .upgrade) pkg=$(sel .package)
+from=$(sel .from) to=$(sel .to)
+# Uptide's default executor model and effort (packages/core/src/llm/pricing.ts DEFAULT_MODELS,
+# capabilities.ts defaultEffort), used by both arms.
+model=claude-sonnet-5-5 effort=medium
+
+run=$(uuidgen | tr '[:upper:]' '[:lower:]' | cut -c1-8)
+dir=$out/runs/$run
+mkdir -p "$dir"
+printf '%s\t%s\t%s\n' "$run" "$id" "$arm" >>"$out/key.tsv"
+git clone -q "https://github.com/$repo.git" "$dir/repo"
+cd "$dir/repo"
+git checkout -q -b bench-base "$parent"
+git remote set-url --push origin no-push
+git config user.name "UpgradeBench" && git config user.email bench@uptide.invalid
+export npm_config_ignore_scripts=true YARN_ENABLE_SCRIPTS=0
+# A developer's checkout is installed; Uptide refuses one that is not. Untimed, both arms.
+bash -c "$(sel .checks.install)" >"$dir/setup.log" 2>&1
+
+start=$(date +%s) status=0 cost=0
+case $arm in
+claude)
+  prompt="Upgrade $pkg from $from to $to. Make the code compile and work with the new version, keep behavior correct, and make sure type-check, lint and tests pass. Commit and summarize what to review."
+  # --bare: none of this machine's hooks, plugins, memory or CLAUDE.md; --add-dir loads the
+  # repository's own CLAUDE.md as a plain `claude -p` in it would. Bash runs only inside
+  # Claude Code's sandbox (claude-sandbox.json); anything that would prompt is denied.
+  claude -p --bare --add-dir "$PWD" --model "$model" --effort "$effort" \
+    --settings "$here/claude-sandbox.json" --permission-mode acceptEdits --permission-prompts none \
+    --no-session-persistence --output-format json --max-budget-usd "${CLAUDE_CAP_USD:-6}" \
+    "$prompt" >"$dir/agent.json" 2>"$dir/agent.log" || status=$?
+  # Claude Code does not know this model's price and reports it at an older Sonnet's; price its
+  # tokens with Uptide's table (pricing.ts, per million: input, output, cache read, 5m write),
+  # the one Uptide's own cost uses.
+  cost=$(jq '[.modelUsage // {} | to_entries[]
+    | (if (.key | test("haiku")) then [1, 5, 0.1, 1.25] else [2, 10, 0.2, 2.5] end) as $p
+    | (.value.inputTokens * $p[0] + .value.outputTokens * $p[1]
+      + .value.cacheReadInputTokens * $p[2] + .value.cacheCreationInputTokens * $p[3]) / 1e6]
+    | add // 0' "$dir/agent.json" 2>/dev/null || echo 0)
+  jq -r '.result // ""' "$dir/agent.json" >"$dir/summary.md" 2>/dev/null || : >"$dir/summary.md"
+  ;;
+uptide)
+  UPTIDE_MODEL=$model node "$here/../packages/cli/dist/index.js" fix "$pkg" --target "$to" \
+    --json >"$dir/agent.json" 2>"$dir/agent.log" || status=$?
+  branch=$(git for-each-ref --format='%(refname:short)' "refs/heads/uptide/$pkg-*" | head -1)
+  [ -n "$branch" ] && git checkout -q "$branch"
+  cost=$(jq '.llm.costUsd // 0' "$dir/agent.json" 2>/dev/null || echo 0)
+  cp "$(jq -r '.prBody // empty' "$dir/agent.json" 2>/dev/null)" "$dir/summary.md" 2>/dev/null ||
+    tail -5 "$dir/agent.log" >"$dir/summary.md"
+  ;;
+human)
+  git checkout -q "$upgrade"
+  git log -1 --format=%B >"$dir/summary.md"
+  ;;
+*) echo "unknown arm $arm" >&2 && exit 2 ;;
+esac
+wall=$(($(date +%s) - start)) cost=${cost:-0}
+dirty=$(git status --porcelain --untracked-files=no -- . ':!.uptide' | wc -l | tr -d ' ')
+jq -n --arg id "$id" --arg head "$(git rev-parse HEAD)" --argjson status "$status" \
+  --argjson cost "$cost" --argjson wall "$wall" --argjson dirty "$dirty" \
+  '{id: $id, head: $head, exit: $status, costUsd: $cost, wallSeconds: $wall, uncommittedFiles: $dirty}' \
+  >"$dir/meta.json"
+echo "$run $(cat "$dir/meta.json")"
diff --git a/bench/score.mjs b/bench/score.mjs
new file mode 100644
index 00000000..3c5ad20f
--- /dev/null
+++ b/bench/score.mjs
@@ -0,0 +1,188 @@
+// Scores every run in $BENCH_OUT/runs the same way, blind to arm: it never reads key.tsv.
+// The reference of a repository is the run whose head is the human's upgrade commit.
+//
+//   BENCH_OUT=<dir> node bench/score.mjs             writes $BENCH_OUT/scores.json
+//   BENCH_OUT=<dir> node bench/score.mjs --unblind   then prints the table with arms joined in
+//
+// Measures, on code files only (lockfiles, package.json and docs left out):
+// - coverage: human hunks (git diff -U0 parent..upgrade) whose old lines the run also changed;
+//   a pure insertion counts as the two lines around it. Missed hunks are the candidates for
+//   escaped regressions, read by hand.
+// - unrelated: run hunks in files the human left alone that never name the package.
+// - regressions: local checks and CI checks that fail on the run and pass on the reference.
+// - unverified: whether the run's summary or PR body says what it did not verify.
+// - silent changes (ADR 0017): the selection's `silent` sites, behavior the upgrade must keep that
+//   no check shows. Caught when the run's diff touches the site's line and the file at the run's
+//   head has the `keep` edit, or when the PR body names the record. A silent false positive is a
+//   site a PR body's "Behavior change (<record>)" line names that the selection does not.
+import { execFileSync } from 'node:child_process';
+import { existsSync, readdirSync, readFileSync, writeFileSync } from 'node:fs';
+import { join } from 'node:path';
+
+const CODE = /\.(c|m)?(t|j)sx?$/;
+const UNVERIFIED =
+  /not (been )?(verified|tested|checked|run)|did(n't| not) (run|verify|test|check)|could(n't| not) (run|verify|test)|unable to|untested|unverified|manual(ly)? (review|check|test)|needs? (manual|human)|not covered|wasn't able/i;
+
+const read = (file, fallback) =>
+  existsSync(file) ? JSON.parse(readFileSync(file, 'utf8')) : fallback;
+const git = (repo, ...args) =>
+  execFileSync('git', ['-C', repo, ...args], { encoding: 'utf8', maxBuffer: 1 << 28 });
+
+/** Hunks of `git diff -U0 a b` on code files: file, old start, old count. */
+export function hunks(diff) {
+  const found = [];
+  let file;
+  for (const line of diff.split('\n')) {
+    const header = /^diff --git a\/(.+) b\//.exec(line);
+    if (header) file = CODE.test(header[1]) ? header[1] : undefined;
+    const hunk = /^@@ -(\d+)(?:,(\d+))? /.exec(line);
+    if (hunk && file)
+      found.push({
+        file,
+        start: Number(hunk[1]),
+        count: hunk[2] === undefined ? 1 : Number(hunk[2]),
+      });
+  }
+  return found;
+}
+/** Old-side lines a hunk touches; an insertion after line n touches n and n + 1. */
+export const lines = (h) =>
+  h.count === 0 ? [h.start, h.start + 1] : Array.from({ length: h.count }, (_, i) => h.start + i);
+
+export function compare(human, agent) {
+  const touched = new Set(agent.flatMap((h) => lines(h).map((l) => `${h.file}:${l}`)));
+  const missed = human.filter((h) => !lines(h).some((l) => touched.has(`${h.file}:${l}`)));
+  return { covered: human.length - missed.length, missed };
+}
+
+/** Silent sites caught by an edit or by a decision citing the record, and silent false positives. */
+export function silent(entry, agent, summary, headText) {
+  const truth = entry.silent ?? [];
+  const touched = new Set(agent.flatMap((h) => lines(h).map((l) => `${h.file}:${l}`)));
+  const edited = truth.filter(
+    (s) => touched.has(`${s.file}:${s.line}`) && new RegExp(s.keep).test(headText(s.file)),
+  );
+  const decided = truth.filter((s) => !edited.includes(s) && summary.includes(s.record));
+  const known = new Set(truth.map((s) => `${s.record} ${s.file}:${s.line}`));
+  const named = [...summary.matchAll(/\*\*Behavior change \(([^)\s]+)\):\*\*([^\n]*)/g)].flatMap(
+    ([, record, line]) =>
+      [...line.matchAll(/`([^`\s]+):(\d+)`/g)].map(([, file, n]) => `${record} ${file}:${n}`),
+  );
+  const at = (s) => `${s.file}:${s.line}`;
+  return {
+    silentSites: truth.length,
+    silentEdited: edited.map(at),
+    silentDecided: decided.map(at),
+    silentFalsePositives: [...new Set(named.filter((n) => !known.has(n)))],
+  };
+}
+
+function score(out, selection, run) {
+  const dir = join(out, 'runs', run);
+  const meta = read(join(dir, 'meta.json'));
+  const entry = selection.repos.find((r) => r.id === meta.id);
+  const repo = join(dir, 'repo');
+  const human = hunks(git(repo, 'diff', '-U0', '--no-renames', entry.parent, entry.upgrade));
+  const agent = hunks(git(repo, 'diff', '-U0', '--no-renames', entry.parent, meta.head));
+  const { covered, missed } = compare(human, agent);
+  const humanFiles = new Set(human.map((h) => h.file));
+  const names = new RegExp(`['"]${entry.package.replace(/[/.]/g, '\\$&')}(/[^'"]*)?['"]`);
+  const unrelated = agent.filter((h) => {
+    if (humanFiles.has(h.file)) return false;
+    try {
+      return !names.test(git(repo, 'show', `${entry.parent}:${h.file}`));
+    } catch {
+      return false; // a file the run created
+    }
+  });
+  const summaryFile = join(dir, 'summary.md');
+  const summary = existsSync(summaryFile) ? readFileSync(summaryFile, 'utf8') : '';
+  const headText = (file) => {
+    try {
+      return git(repo, 'show', `${meta.head}:${file}`);
+    } catch {
+      return '';
+    }
+  };
+  return {
+    run,
+    id: meta.id,
+    head: meta.head,
+    reference: meta.head === entry.upgrade,
+    exit: meta.exit,
+    costUsd: meta.costUsd,
+    wallSeconds: meta.wallSeconds,
+    uncommittedFiles: meta.uncommittedFiles,
+    humanHunks: human.length,
+    covered,
+    missed: missed.map((h) => `${h.file}:${h.start}`),
+    agentHunks: agent.length,
+    agentFiles: new Set(agent.map((h) => h.file)).size,
+    unrelated: unrelated.map((h) => `${h.file}:${h.start}`),
+    unverified: UNVERIFIED.exec(summary)?.[0] ?? null,
+    ...silent(entry, agent, summary, headText),
+    checks: read(join(dir, 'checks.json'), {}),
+    ci: read(join(dir, 'ci.json'), []).map((c) => ({
+      name: `${c.workflow}/${c.name}`,
+      bucket: c.bucket,
+    })),
+  };
+}
+
+export function regressions(row, reference) {
+  if (!reference || row.reference) return [];
+  const local = Object.entries(row.checks)
+    .filter(([step, code]) => code !== 0 && reference.checks[step] === 0)
+    .map(([step]) => `local ${step}`);
+  const passed = new Set(reference.ci.filter((c) => c.bucket === 'pass').map((c) => c.name));
+  const ci = row.ci
+    .filter((c) => c.bucket === 'fail' && passed.has(c.name))
+    .map((c) => `ci ${c.name}`);
+  return [...local, ...ci];
+}
+
+function table(rows, arms) {
+  const ci = (r) => {
+    const n = (b) => r.ci.filter((c) => c.bucket === b).length;
+    return r.ci.length ? `${n('pass')} pass, ${n('fail')} fail` : 'none';
+  };
+  const checks = (r) =>
+    Object.entries(r.checks)
+      .map(([s, c]) => `${s} ${c === 0 ? 'ok' : 'FAIL'}`)
+      .join(', ') || 'not run';
+  const lines = [
+    '| repo | arm | exit | coverage | missed | unrelated | regressions vs human | silent changes caught | silent FP | states unverified | local checks | fork CI | cost | wall |',
+    '|---|---|---|---|---|---|---|---|---|---|---|---|---|---|',
+  ];
+  const caught = (r) =>
+    r.silentSites
+      ? `${r.silentEdited.length + r.silentDecided.length}/${r.silentSites} (edit ${r.silentEdited.length})`
+      : 'n/a';
+  const sorted = [...rows].sort(
+    (a, b) => a.id.localeCompare(b.id) || arms[a.run].localeCompare(arms[b.run]),
+  );
+  for (const r of sorted)
+    lines.push(
+      `| ${r.id} | ${arms[r.run]} | ${r.exit} | ${r.covered}/${r.humanHunks} | ${r.missed.length} | ${r.unrelated.length} | ${r.regressions.join(', ') || 'none'} | ${caught(r)} | ${r.silentFalsePositives.length} | ${r.unverified ? 'yes' : 'no'} | ${checks(r)} | ${ci(r)} | $${Number(r.costUsd).toFixed(2)} | ${Math.round(r.wallSeconds / 60)} min |`,
+    );
+  return lines.join('\n');
+}
+
+if (process.argv[1] === new URL(import.meta.url).pathname) {
+  const out = process.env.BENCH_OUT;
+  if (!out) throw new Error('set BENCH_OUT');
+  const selection = JSON.parse(readFileSync(new URL('./selection.json', import.meta.url), 'utf8'));
+  const rows = readdirSync(join(out, 'runs')).map((run) => score(out, selection, run));
+  for (const row of rows)
+    row.regressions = regressions(
+      row,
+      rows.find((r) => r.reference && r.id === row.id),
+    );
+  writeFileSync(join(out, 'scores.json'), `${JSON.stringify(rows, null, 2)}\n`);
+  if (process.argv.includes('--unblind')) {
+    const key = readFileSync(join(out, 'key.tsv'), 'utf8').trim().split('\n');
+    console.log(
+      table(rows, Object.fromEntries(key.map((l) => [l.split('\t')[0], l.split('\t')[2]]))),
+    );
+  }
+}
diff --git a/bench/score.test.mjs b/bench/score.test.mjs
new file mode 100644
index 00000000..cf1ec833
--- /dev/null
+++ b/bench/score.test.mjs
@@ -0,0 +1,73 @@
+import assert from 'node:assert/strict';
+import { test } from 'node:test';
+import { compare, hunks, regressions, silent } from './score.mjs';
+
+const diff = (...parts) => parts.join('\n');
+const human = hunks(
+  diff(
+    'diff --git a/src/a.ts b/src/a.ts',
+    '@@ -3 +3 @@',
+    '@@ -10,0 +11,2 @@',
+    'diff --git a/package-lock.json b/package-lock.json',
+    '@@ -1,4 +1,4 @@',
+    'diff --git a/src/b.tsx b/src/b.tsx',
+    '@@ -7,2 +7,0 @@',
+  ),
+);
+
+test('code hunks only, with old start and count', () => {
+  assert.deepEqual(human, [
+    { file: 'src/a.ts', start: 3, count: 1 },
+    { file: 'src/a.ts', start: 10, count: 0 },
+    { file: 'src/b.tsx', start: 7, count: 2 },
+  ]);
+});
+
+test('a hunk is covered when the run touches one of its old lines', () => {
+  const agent = hunks(diff('diff --git a/src/a.ts b/src/a.ts', '@@ -2,2 +2,2 @@', '@@ -11 +11 @@'));
+  const { covered, missed } = compare(human, agent);
+  assert.equal(covered, 2); // line 3, and the insertion after 10 by touching 11
+  assert.deepEqual(missed, [{ file: 'src/b.tsx', start: 7, count: 2 }]);
+});
+
+test('regressions are failures the reference does not have', () => {
+  const reference = {
+    reference: true,
+    checks: { test: 0, lint: 1 },
+    ci: [{ name: 'ci/build', bucket: 'pass' }],
+  };
+  const row = { checks: { test: 1, lint: 1 }, ci: [{ name: 'ci/build', bucket: 'fail' }] };
+  assert.deepEqual(regressions(row, reference), ['local test', 'ci ci/build']);
+});
+
+test('silent changes: caught by the keep edit at the site or a decision naming the record; a named site the selection lacks is a false positive', () => {
+  const record = 'zod/mcp-input-schema-additional-properties';
+  const entry = {
+    silent: [69, 83, 102].map((line) => ({
+      file: 'src/tools/index.ts',
+      line,
+      record,
+      keep: '\\.strict\\(\\)|strictObject\\(',
+    })),
+  };
+  const agent = hunks(
+    diff('diff --git a/src/tools/index.ts b/src/tools/index.ts', '@@ -69 +69 @@'),
+  );
+  const head = () => 'function strictInput(shape) { return z.object(shape).strict(); }';
+  assert.deepEqual(silent(entry, agent, '', head), {
+    silentSites: 3,
+    silentEdited: ['src/tools/index.ts:69'],
+    silentDecided: [],
+    silentFalsePositives: [],
+  });
+  // The line touched without the edit is not caught.
+  assert.deepEqual(silent(entry, agent, '', () => 'z.object(shape)').silentEdited, []);
+  const body = `- **Behavior change (${record}):** … Not applied at \`src/tools/index.ts:83\`, \`src/other.ts:4\`: recommended`;
+  assert.deepEqual(silent(entry, agent, body, head), {
+    silentSites: 3,
+    silentEdited: ['src/tools/index.ts:69'],
+    silentDecided: ['src/tools/index.ts:83', 'src/tools/index.ts:102'],
+    silentFalsePositives: [`${record} src/other.ts:4`],
+  });
+  assert.equal(silent({}, agent, body, head).silentSites, 0);
+});
diff --git a/bench/selection.json b/bench/selection.json
new file mode 100644
index 00000000..83a1e612
--- /dev/null
+++ b/bench/selection.json
@@ -0,0 +1,115 @@
+{
+  "$comment": "UpgradeBench v0 pilot (UPT-24): three held-out public repositories, each with a human's merged upgrade in the range of a verified pack. None is in any pack's ground-truth.json (bench/excluded.json). Committed before either arm ran. checks are the repository's own commands, run by bench/check.sh with lifecycle scripts off.",
+  "selected": "2026-10-15",
+  "repos": [
+    {
+      "id": "zod-calmcp",
+      "repo": "consetto/calmcp",
+      "license": "MIT",
+      "pack": "zod",
+      "package": "zod",
+      "from": "3.25.76",
+      "to": "4.6.5",
+      "parent": "741de4eba98eb96b4bed817d8974e9e8c6eec867",
+      "upgrade": "bdaef39c34705b2dfc1065a59ec683288a2e99d2",
+      "silent": [
+        {
+          "file": "src/tools/index.ts",
+          "line": 69,
+          "record": "zod/mcp-input-schema-additional-properties",
+          "keep": "\\.strict\\(\\)|strictObject\\("
+        },
+        {
+          "file": "src/tools/index.ts",
+          "line": 83,
+          "record": "zod/mcp-input-schema-additional-properties",
+          "keep": "\\.strict\\(\\)|strictObject\\("
+        },
+        {
+          "file": "src/tools/index.ts",
+          "line": 102,
+          "record": "zod/mcp-input-schema-additional-properties",
+          "keep": "\\.strict\\(\\)|strictObject\\("
+        },
+        {
+          "file": "src/tools/index.ts",
+          "line": 119,
+          "record": "zod/mcp-input-schema-additional-properties",
+          "keep": "\\.strict\\(\\)|strictObject\\("
+        },
+        {
+          "file": "src/tools/index.ts",
+          "line": 148,
+          "record": "zod/mcp-input-schema-additional-properties",
+          "keep": "\\.strict\\(\\)|strictObject\\("
+        }
+      ],
+      "note": "npm, single package. The upgrade (merged in PR #22) changes 3 source files, a test and a script: z.string().uuid() to z.guid(), .strict() tool schemas, a _def walker rewritten for zod 4. Mostly behavior, little a compiler sees. The commit carries a Co-Authored-By: Claude trailer.",
+      "ci": ".github/workflows/ci.yml: build (lint, typecheck, test, build, test:e2e), btp-descriptors, docker; tool-surface.yml",
+      "checks": {
+        "install": "npm ci --ignore-scripts",
+        "typecheck": "npm run typecheck",
+        "lint": "npm run lint",
+        "test": "npm test"
+      }
+    },
+    {
+      "id": "stripe-dms-saas",
+      "repo": "AntelopeJS/dms-saas",
+      "license": "Apache-2.0",
+      "pack": "stripe",
+      "package": "stripe",
+      "from": "18.5.0",
+      "to": "22.6.2",
+      "parent": "6390f434622db5d6e546854b435fb1017c3cc665",
+      "upgrade": "f992f335089cfb17ca2b86d8d9d6a908ddbaee2a",
+      "note": "pnpm 10.2.0 workspace of 2 packages plus a nested frontend-vue project with its own lockfile. The upgrade (PR #70) changes 14 source files: subscriptions.cancel options, schedule phase iterations to duration, allowed_payment_method_types, billing mode, apiVersion basil to dahlia. dms-saas type-checks only after the interface package is built.",
+      "ci": ".github/workflows/ci.yml: static (build, lint, typecheck, knip, check:exports), unit (vitest), frontend",
+      "checks": {
+        "install": "corepack pnpm install --frozen-lockfile --ignore-scripts && corepack pnpm --dir packages/dms-saas/frontend-vue install --frozen-lockfile --ignore-scripts",
+        "typecheck": "corepack pnpm --filter @antelopejs/interface-dms-saas build && corepack pnpm -r typecheck",
+        "lint": "corepack pnpm -r lint",
+        "test": "corepack pnpm --filter @antelopejs/dms-saas test:unit"
+      }
+    },
+    {
+      "id": "react-enki",
+      "repo": "entur/enki",
+      "license": "EUPL-1.2",
+      "pack": "react",
+      "package": "react",
+      "from": "18.3.1",
+      "to": "19.2.0",
+      "parent": "08cf2a70267185a74c362c15bab3b3826e4be3f2",
+      "upgrade": "ed37dd231b49628b7611760dfcde750e9c5a8e02",
+      "note": "npm, single package (Vite). The upgrade is the merge of PR #1760 (scored against its first parent): react, react-dom and their types to 19, react-leaflet 4 to 5, MutableRefObject to RefObject, useRef arguments, useReducer generics, 11 source files.",
+      "ci": ".github/workflows/pull-request-build-external.yml: fork pull requests, npm ci, prettier check, vitest, build (tsc and vite)",
+      "checks": {
+        "install": "npm ci --ignore-scripts",
+        "typecheck": "./node_modules/.bin/tsc --noEmit",
+        "lint": "npm run check",
+        "test": "./node_modules/.bin/vitest run"
+      }
+    }
+  ],
+  "backups": [
+    {
+      "repo": "sukhmal/servicenow-mcp",
+      "package": "zod",
+      "parent": "9c71205e26752ecb5a14cf95b26fcbe475af1839",
+      "upgrade": "0406fba4baf28c9eba8d0690d70eab1b5e38f8e7"
+    },
+    {
+      "repo": "likecoin/likecoin-api-public",
+      "package": "stripe",
+      "parent": "4526998344fb4905034c9248bbed4b80e0fde242",
+      "upgrade": "12480cda61716226155dec06a98a9cd67737741b"
+    },
+    {
+      "repo": "Tietokilta/web",
+      "package": "next",
+      "parent": "f6f51b539594504d2d91adff3b5a14e5dc075b9f",
+      "upgrade": "d96361254033243cb8165bc3277f0be15649aba7"
+    }
+  ]
+}