diff --git a/.github/scripts/bench_watch.sh b/.github/scripts/bench_watch.sh
new file mode 100755
index 00000000..bb982cf6
--- /dev/null
+++ b/.github/scripts/bench_watch.sh
@@ -0,0 +1,90 @@
+#!/usr/bin/env bash
+# Copy to lightcone-cli:.github/scripts/bench_watch.sh
+# Watch the lightcone-bench run dispatched for a PR commit and keep ONE PR comment
+# (found by the marker below) up to date: the run link while it runs, the outcome
+# when it ends. A dispatch returns no run id, so the run is found by the sha in its
+# title — the bench workflow's run-name carries stack_ref for exactly this reason.
+#
+# When the run ends, the comment also carries the run's "Overall" row (all agents
+# pooled: mean reward, mean steps/tokens/cost/time, total cost), read from the
+# `overall` block of the run's results.json artifact.
+#
+# Env: BENCH_TOKEN  reads runs in lightcone-bench (the dispatch token)
+#      GH_TOKEN     comments on this repo (the job's GITHUB_TOKEN, pull-requests: write)
+#      REPO         owner/name of this repo      PR   pull request number
+#      SHA          head sha being benchmarked   POLL_SECONDS (default 600)
+#      MAX_POLLS    give up after this many polls (default 18 → 3 h)
+set -uo pipefail
+BENCH=LightconeResearch/lightcone-bench
+API=https://api.github.com
+MARKER="<!-- lightcone-bench-run -->"
+POLL_SECONDS="${POLL_SECONDS:-600}"
+MAX_POLLS="${MAX_POLLS:-18}"
+short="${SHA:0:7}"
+
+bench_api() { curl -sf -H "Authorization: Bearer $BENCH_TOKEN" -H "Accept: application/vnd.github+json" "$@"; }
+repo_api()  { curl -sf -H "Authorization: Bearer $GH_TOKEN"    -H "Accept: application/vnd.github+json" "$@"; }
+
+upsert_comment() { # $1 = markdown body; creates the marker comment or edits it in place
+  local payload id
+  payload=$(jq -n --arg m "$MARKER" --arg b "$1" '{body: ($m + "\n" + $b)}')
+  id=$(repo_api "$API/repos/$REPO/issues/$PR/comments?per_page=100" \
+       | jq -r --arg m "$MARKER" '[.[] | select(.body | startswith($m))] | first | .id // empty')
+  if [ -n "$id" ]; then
+    repo_api -X PATCH "$API/repos/$REPO/issues/comments/$id" -d "$payload" >/dev/null
+  else
+    repo_api -X POST "$API/repos/$REPO/issues/$PR/comments" -d "$payload" >/dev/null
+  fi
+}
+
+overall_table() { # markdown table of the run's pooled results; empty if unavailable
+  local url dir
+  url=$(bench_api "$API/repos/$BENCH/actions/runs/$run_id/artifacts?name=results" \
+        | jq -r '.artifacts[0].archive_download_url // empty')
+  [ -n "$url" ] || return 0
+  dir=$(mktemp -d)
+  curl -sfL -H "Authorization: Bearer $BENCH_TOKEN" "$url" -o "$dir/results.zip" \
+    && unzip -qo "$dir/results.zip" results.json -d "$dir" || return 0
+  jq -r '.overall // empty | select(.trials > 0)
+    | def f(d): if . == null then "—" elif d == 0 then (round | tostring) else
+        ((. * pow(10; d) | round | tostring) as $s
+         | ("0" * ([d + 1 - ($s | length), 0] | max)) + $s
+         | .[:-d] + "." + .[-d:]) end;
+      "| trials | scored | mean reward | steps | tool calls | shell calls | out tokens (k) | cached % | cost $ | agent min | total cost $ |",
+      "|---|---|---|---|---|---|---|---|---|---|---|",
+      "| \(.trials) | \(.scored) | \(.mean_reward | f(2)) | \(.agent_steps | f(0)) | \(.tool_calls_total | f(0)) | \(.shell_calls | f(0)) | \(.completion_ktokens | f(1)) | \(.cached_pct | f(0)) | \(.cost_usd | f(3)) | \(.agent_min | f(1)) | \(.total_cost_usd | f(3)) |"' \
+    "$dir/results.json"
+}
+
+# 1. Find the run: it shows up a few seconds after the dispatch.
+run_id=""; run_url=""
+for _ in $(seq 1 12); do
+  sleep 5
+  read -r run_id run_url < <(bench_api "$API/repos/$BENCH/actions/workflows/benchmark.yml/runs?event=workflow_dispatch&per_page=30" \
+    | jq -r --arg sha "$SHA" '[.workflow_runs[] | select(.display_title | contains($sha))]
+                              | sort_by(.created_at) | last | select(. != null) | "\(.id) \(.html_url)"')
+  [ -n "$run_id" ] && break
+done
+if [ -z "$run_id" ]; then
+  upsert_comment "**lightcone-bench** — dispatched a run for \`$short\` but could not find it in the queue; look under [lightcone-bench → Actions](https://github.com/$BENCH/actions/workflows/benchmark.yml)."
+  exit 0
+fi
+upsert_comment "**lightcone-bench** — benchmarking \`$short\`: [run $run_id]($run_url) ⏳ in progress (checked every $((POLL_SECONDS / 60)) min)."
+
+# 2. Wait for it, editing the same comment when it ends.
+for _ in $(seq 1 "$MAX_POLLS"); do
+  sleep "$POLL_SECONDS"
+  read -r status conclusion < <(bench_api "$API/repos/$BENCH/actions/runs/$run_id" | jq -r '"\(.status) \(.conclusion)"')
+  [ "${status:-}" = "completed" ] || continue
+  case "$conclusion" in
+    success)   icon="✅"; word="passed" ;;
+    cancelled) icon="⚪"; word="was cancelled" ;;
+    *)         icon="❌"; word="failed ($conclusion)" ;;
+  esac
+  body="**lightcone-bench** — benchmark of \`$short\` $icon $word: [run $run_id]($run_url) — the per-agent tables, baseline deltas and trace report are in its job summary."
+  table=$(overall_table)
+  [ -n "$table" ] && body="$body"$'\n\n'"All agents pooled (reward averaged over scored trials, the rest over all trials):"$'\n\n'"$table"
+  upsert_comment "$body"
+  exit 0
+done
+upsert_comment "**lightcone-bench** — benchmark of \`$short\` is still running after $((MAX_POLLS * POLL_SECONDS / 3600)) h: [run $run_id]($run_url)."
diff --git a/.github/workflows/benchmark-baseline.yml b/.github/workflows/benchmark-baseline.yml
new file mode 100644
index 00000000..7134517c
--- /dev/null
+++ b/.github/workflows/benchmark-baseline.yml
@@ -0,0 +1,19 @@
+# Copy to lightcone-cli:.github/workflows/benchmark-baseline.yml
+# Every merge to main refreshes lightcone-bench's stored stack baseline (skills from
+# agent-skills main installed, three attempts per agent, matching the PR runs it is
+# compared with).
+name: benchmark-baseline
+on:
+  push:
+    branches: [main]
+jobs:
+  dispatch:
+    runs-on: ubuntu-latest
+    steps:
+      - env:
+          GH_TOKEN: ${{ secrets.BENCH_DISPATCH_TOKEN }}
+        run: |
+          curl -sf -X POST -H "Authorization: Bearer $GH_TOKEN" \
+            -H "Accept: application/vnd.github+json" \
+            https://api.github.com/repos/LightconeResearch/lightcone-bench/actions/workflows/benchmark.yml/dispatches \
+            -d '{"ref":"main","inputs":{"task":"lightcone-cli/snae-build","use_skills":"true","attempts":"3","stack_ref":"${{ github.sha }}","save_baseline":true}}'
diff --git a/.github/workflows/benchmark-on-comment.yml b/.github/workflows/benchmark-on-comment.yml
new file mode 100644
index 00000000..652f8ce6
--- /dev/null
+++ b/.github/workflows/benchmark-on-comment.yml
@@ -0,0 +1,59 @@
+# Copy to lightcone-cli:.github/workflows/benchmark-on-comment.yml  (with bench_watch.sh)
+# Comment "/benchmark" on a PR (maintainers only) to benchmark that PR's stack on
+# demand — a draft PR, or a re-run — with the skills from agent-skills main
+# installed (the skills axis is held fixed here; varying it is the agent-skills
+# senders' job). One comment on the PR links the run and is edited with the
+# outcome and the pooled results when it ends (checked every 10 minutes). Three
+# attempts per agent, run in parallel.
+name: benchmark-on-comment
+on:
+  issue_comment:
+    types: [created]
+concurrency:
+  group: benchmark-watch-${{ github.event.issue.number }}
+  cancel-in-progress: true
+jobs:
+  dispatch:
+    if: >
+      github.event.issue.pull_request &&
+      startsWith(github.event.comment.body, '/benchmark') &&
+      contains(fromJSON('["OWNER","MEMBER","COLLABORATOR"]'), github.event.comment.author_association)
+    runs-on: ubuntu-latest
+    timeout-minutes: 200
+    permissions:
+      contents: read
+      pull-requests: write
+    steps:
+      - uses: actions/checkout@v4
+      - name: Resolve PR head sha
+        id: pr
+        env:
+          GH_TOKEN: ${{ secrets.GITHUB_TOKEN }}
+        run: |
+          sha=$(curl -sf -H "Authorization: Bearer $GH_TOKEN" \
+            "${{ github.event.issue.pull_request.url }}" | jq -r .head.sha)
+          echo "sha=$sha" >> "$GITHUB_OUTPUT"
+      - name: Dispatch lightcone-bench (stack under test = PR head)
+        env:
+          GH_TOKEN: ${{ secrets.BENCH_DISPATCH_TOKEN }}
+          SHA: ${{ steps.pr.outputs.sha }}
+        run: |
+          curl -sf -X POST -H "Authorization: Bearer $GH_TOKEN" \
+            -H "Accept: application/vnd.github+json" \
+            https://api.github.com/repos/LightconeResearch/lightcone-bench/actions/workflows/benchmark.yml/dispatches \
+            -d "{\"ref\":\"main\",\"inputs\":{\"task\":\"lightcone-cli/snae-build\",\"use_skills\":\"true\",\"attempts\":\"3\",\"stack_ref\":\"$SHA\"}}"
+      - name: Ack with a rocket
+        env:
+          GH_TOKEN: ${{ secrets.GITHUB_TOKEN }}
+        run: |
+          curl -sf -X POST -H "Authorization: Bearer $GH_TOKEN" \
+            "https://api.github.com/repos/${{ github.repository }}/issues/comments/${{ github.event.comment.id }}/reactions" \
+            -d '{"content":"rocket"}'
+      - name: Link the run on the PR and report its outcome
+        env:
+          BENCH_TOKEN: ${{ secrets.BENCH_DISPATCH_TOKEN }}
+          GH_TOKEN: ${{ secrets.GITHUB_TOKEN }}
+          REPO: ${{ github.repository }}
+          PR: ${{ github.event.issue.number }}
+          SHA: ${{ steps.pr.outputs.sha }}
+        run: bash .github/scripts/bench_watch.sh
diff --git a/.github/workflows/benchmark-on-pr.yml b/.github/workflows/benchmark-on-pr.yml
new file mode 100644
index 00000000..b6dc1f0f
--- /dev/null
+++ b/.github/workflows/benchmark-on-pr.yml
@@ -0,0 +1,47 @@
+# Copy to lightcone-cli:.github/workflows/benchmark-on-pr.yml  (with bench_watch.sh)
+# Every non-draft PR — opened, pushed to, reopened, or marked ready for review — is
+# benchmarked against its head commit, with the skills from agent-skills main
+# installed (the skills axis is held fixed here; varying it is the agent-skills
+# senders' job). Draft PRs are not run automatically: comment "/benchmark" on them
+# (benchmark-on-comment.yml) when a run is wanted. Fork PRs are skipped — they do
+# not receive this repo's secrets. One comment on the PR links the run and is
+# edited with the outcome and the pooled results when it ends (checked every 10
+# minutes). Three attempts per agent, run in parallel.
+name: benchmark-on-pr
+on:
+  pull_request:
+    types: [opened, synchronize, reopened, ready_for_review]
+concurrency:
+  # A new push replaces the watcher for this PR (the earlier bench run itself keeps
+  # going; its result just stops being reported here).
+  group: benchmark-watch-${{ github.event.pull_request.number }}
+  cancel-in-progress: true
+jobs:
+  dispatch:
+    if: >
+      github.event.pull_request.draft == false &&
+      github.event.pull_request.head.repo.full_name == github.repository
+    runs-on: ubuntu-latest
+    timeout-minutes: 200
+    permissions:
+      contents: read
+      pull-requests: write
+    steps:
+      - uses: actions/checkout@v4
+      - name: Dispatch lightcone-bench (stack under test = PR head)
+        env:
+          GH_TOKEN: ${{ secrets.BENCH_DISPATCH_TOKEN }}
+          SHA: ${{ github.event.pull_request.head.sha }}
+        run: |
+          curl -sf -X POST -H "Authorization: Bearer $GH_TOKEN" \
+            -H "Accept: application/vnd.github+json" \
+            https://api.github.com/repos/LightconeResearch/lightcone-bench/actions/workflows/benchmark.yml/dispatches \
+            -d "{\"ref\":\"main\",\"inputs\":{\"task\":\"lightcone-cli/snae-build\",\"use_skills\":\"true\",\"attempts\":\"3\",\"stack_ref\":\"$SHA\"}}"
+      - name: Link the run on the PR and report its outcome
+        env:
+          BENCH_TOKEN: ${{ secrets.BENCH_DISPATCH_TOKEN }}
+          GH_TOKEN: ${{ secrets.GITHUB_TOKEN }}
+          REPO: ${{ github.repository }}
+          PR: ${{ github.event.pull_request.number }}
+          SHA: ${{ github.event.pull_request.head.sha }}
+        run: bash .github/scripts/bench_watch.sh