diff --git a/.gitea/workflows/agent.yml b/.gitea/workflows/agent.yml
index 9aa81f3..743d2b5 100644
--- a/.gitea/workflows/agent.yml
+++ b/.gitea/workflows/agent.yml
@@ -185,7 +185,7 @@ jobs:
           FILES: ${{ steps.imgs.outputs.files }}   # opencode -f image flags (vision agents only)
         run: bash "$SCRIPTS/run-agent.sh"
 
-      - name: Build activity log (tool calls + reasoning) from the event stream
+      - name: Build run report (tool calls + input/output tokens + $ cost) from the event stream
         id: log
         env:
           SCRIPTS: ${{ runner.temp }}/agents-scripts
diff --git a/.gitea/workflows/scripts/build-activity-log.sh b/.gitea/workflows/scripts/build-activity-log.sh
index 5349690..15a6866 100755
--- a/.gitea/workflows/scripts/build-activity-log.sh
+++ b/.gitea/workflows/scripts/build-activity-log.sh
@@ -1,24 +1,51 @@
 #!/usr/bin/env bash
-# Build the activity log — the list of TOOL CALLS the agent made — into /tmp/activity_log.md.
-# Only dev agents (mode=pr) get an activity-log comment — comment-only roles (pm/qa) do no tool calls.
-# NOTE: we deliberately DO NOT include the agent's prose text parts. That final "here's what I did"
-# text is just a restatement of the PR description (already published as the PR body), not a tool
-# call — so it was noise in a section titled "tool calls". The log is the record of ACTIONS taken.
+# Build the RUN REPORT appended to the agent's reply comment: the TOOL CALLS the agent made plus a
+# usage line (input / output tokens + $ cost). Written to /tmp/activity_log.md; the Publish step
+# appends it to the agent's reply. Applies to EVERY agent — @pm/@qa also call tools and cost money.
 #
-# Required env (provided by the workflow step): MODE
+# opencode --format json emits one JSON event per line. `step_finish` events carry, per LLM step,
+# .part.tokens {input, output, reasoning, cache:{read, write}} and .part.cost (USD, already computed
+# by opencode from the model's pricing). We sum them across all steps of the run. Models without
+# pricing (e.g. self-hosted ollama) report cost 0 — shown as $0.0000.
+#
+# Required env (provided by the workflow step): (none needed; reads /tmp/events.jsonl)
 set -u
+E=/tmp/events.jsonl
+: > /tmp/activity_log.md
+[ -s "$E" ] || { echo "no events — empty report"; exit 0; }
 
-if [ "$MODE" != "pr" ]; then
-  echo "skipping activity log for comment-mode agent"; : > /tmp/activity_log.md; exit 0
-fi
+# Tool calls = the ACTIONS taken (not the agent's prose text parts).
 jq -r '
   def trunc(n): if length > n then (.[0:n] + "…") else . end;
   select(.type=="tool_use") |
     (.part.tool // "?") as $t |
     ((.part.state.title // (.part.state.input | tojson | trunc(160)) // "")) as $title |
     "🔧 **" + $t + "**: `" + ($title | trunc(240)) + "`"
-' /tmp/events.jsonl > /tmp/activity_log.md 2>/dev/null || true
-n=$(wc -l < /tmp/activity_log.md 2>/dev/null || echo 0)
-echo "activity log: $n tool calls"
-[ "$n" -eq 0 ] && : > /tmp/activity_log.md
-head -3 /tmp/activity_log.md
+' "$E" > /tmp/tools.md 2>/dev/null || true
+n=$(wc -l < /tmp/tools.md 2>/dev/null || echo 0); n=${n:-0}
+
+# Usage: sum per-step tokens + cost across every step_finish event (tab-separated for `read`).
+read -r COST INP OUT CR CW RE < <(jq -rs '
+  [ .[] | select(.type=="step_finish") | .part ] as $s
+  | [ ([$s[].cost // 0]|add // 0),
+      ([$s[].tokens.input // 0]|add // 0),
+      ([$s[].tokens.output // 0]|add // 0),
+      ([$s[].tokens.cache.read // 0]|add // 0),
+      ([$s[].tokens.cache.write // 0]|add // 0),
+      ([$s[].tokens.reasoning // 0]|add // 0) ]
+  | @tsv' "$E" 2>/dev/null)
+COST=${COST:-0}; INP=${INP:-0}; OUT=${OUT:-0}; CR=${CR:-0}; CW=${CW:-0}; RE=${RE:-0}
+IN_TOTAL=$(( INP + CR + CW ))                          # total input context processed
+COSTF=$(awk -v c="$COST" 'BEGIN{printf "$%.4f", c+0}')
+echo "usage: in=$IN_TOTAL out=$OUT cost=$COSTF (fresh=$INP cache_r=$CR cache_w=$CW reasoning=$RE); tools=$n"
+
+{
+  if [ "$n" -gt 0 ]; then
+    printf '\n\n<details>\n<summary>🔧 %s tool calls · in %s · out %s · %s</summary>\n\n' "$n" "$IN_TOTAL" "$OUT" "$COSTF"
+    cat /tmp/tools.md
+    printf '\n\n<sub>tokens — input %s (fresh %s · cache %sw / %sr) · output %s · reasoning %s · **cost %s**</sub>\n</details>' \
+      "$IN_TOTAL" "$INP" "$CW" "$CR" "$OUT" "$RE" "$COSTF"
+  else
+    printf '\n\n<sub>💰 **%s** · in %s · out %s tokens (cache %sw / %sr)</sub>' "$COSTF" "$IN_TOTAL" "$OUT" "$CW" "$CR"
+  fi
+} > /tmp/activity_log.md
diff --git a/.gitea/workflows/scripts/publish.sh b/.gitea/workflows/scripts/publish.sh
index 08320ce..05cfd31 100755
--- a/.gitea/workflows/scripts/publish.sh
+++ b/.gitea/workflows/scripts/publish.sh
@@ -91,6 +91,9 @@ reply=$(printf '%s' "$reply" | awk -v me="@$NAME" '
 # Prefer the agent's clean delimited PR description; fall back to the whole reply.
 prdesc=$(awk '/BEGIN_PR_DESCRIPTION/{f=1;next} /END_PR_DESCRIPTION/{f=0} f' /tmp/agent_out.md)
 [ -z "$prdesc" ] && prdesc="$reply"
+# Run report (tool calls + input/output tokens + $ cost) built by build-activity-log.sh. Appended to
+# every agent's reply comment so each run reports what it did and what it cost.
+activity="$(cat /tmp/activity_log.md 2>/dev/null || true)"
 
 # comment-only roles (pm/qa): never change files
 if [ "$MODE" != "pr" ]; then
@@ -103,13 +106,13 @@ if [ "$MODE" != "pr" ]; then
   if [ "$NAME" = "qa" ]; then
     PRN=$(resolve_pr)
     if grep -qiE '^[[:space:]]*APPROVE[[:space:]]*$' /tmp/agent_out.md; then
-      post_to "$ISSN" "$(printf '✅ Reviewed PR #%s — looks good.\n\n%s' "${PRN:-?}" "$reply")"
+      post_to "$ISSN" "$(printf '✅ Reviewed PR #%s — looks good.\n\n%s%s' "${PRN:-?}" "$reply" "$activity")"
       trig    "$ISSN" "@pm — @qa approved PR #${PRN:-?} (issue #$ISSN). Over to you."
     elif grep -qiE '^[[:space:]]*BOUNCE:[[:space:]]*@(junior|senior|lead)' /tmp/agent_out.md; then
       dev=$(grep -oiE 'BOUNCE:[[:space:]]*@(junior|senior|lead)' /tmp/agent_out.md | head -1 | grep -oiE '(junior|senior|lead)' | tr '[:upper:]' '[:lower:]')
       [ -z "$dev" ] && [ -n "$PRN" ] && dev=$(curl -sS "${hdr[@]}" "$API/pulls/$PRN" | jq -r '.user.login // "junior"')
       dest="${PRN:-$NUM}"
-      post_to "$dest" "$reply"                       # recommendations, on the PR
+      post_to "$dest" "$reply$activity"              # recommendations, on the PR
       # Bounce budget: count prior "fix attempt" markers on the PR thread; stop after 3.
       prior=$(curl -sS "${hdr[@]}" "$API/issues/$dest/comments?limit=100" | jq -r 'if type=="array" then [.[]|select(.body|test("fix attempt"))]|length else 0 end' 2>/dev/null); prior=${prior:-0}
       if [ "$prior" -ge 3 ]; then
@@ -121,9 +124,9 @@ if [ "$MODE" != "pr" ]; then
       fi
     elif grep -qiE '^[[:space:]]*HALT([_ ]AUTOPILOT)?[[:space:]]*$' /tmp/agent_out.md; then
       [ "$AUTOPILOT" = "true" ] && del_autopilot_label "$ISSN"
-      post_to "$ISSN" "$(printf '🛑 This needs a human decision (not a dev fix) — @ffaerber please take a look.\n\n%s' "$reply")"
+      post_to "$ISSN" "$(printf '🛑 This needs a human decision (not a dev fix) — @ffaerber please take a look.\n\n%s%s' "$reply" "$activity")"
     else
-      post_to "${PRN:-$NUM}" "$reply"               # no verdict yet (a question) — post where qa works
+      post_to "${PRN:-$NUM}" "$reply$activity"       # no verdict yet (a question) — post where qa works
     fi
     exit 0
   fi
@@ -173,7 +176,7 @@ if [ "$MODE" != "pr" ]; then
     done < /tmp/subtasks.txt
     subtext=$(printf '\n\n---\nCreated sub-issues%s (mention an agent on each when ready):%b' "${ms:+ under milestone **$ms**}" "$links")
   fi
-  post "$(printf '%s%s' "$msg" "$subtext")"
+  post "$(printf '%s%s%s' "$msg" "$subtext" "$activity")"
 
   # --- @pm autopilot merge: @pm is the ONLY agent that merges, and ONLY under the autopilot label ---
   # (@qa never merges — it approves and hands back here.) Merge with the PAT (TTOK), not the built-in
@@ -246,16 +249,8 @@ git fetch -q origin 2>/dev/null || true
 prbody=$(printf '%s\n\n---\nResolves #%s' "$prdesc" "$NUM")
 owner=${GITHUB_REPOSITORY%%/*}
 
-# Post the agent's activity trail (tool calls + reasoning) inline in the same comment so
-# each run produces exactly ONE comment (issue #38). Computed once here so every dev-agent
-# exit path (no-changes, PR-open-failed, normal) appends it to the single reply comment.
-activity=""
-if [ -s /tmp/activity_log.md ]; then
-  entries=$(wc -l < /tmp/activity_log.md 2>/dev/null || echo 0)
-  log=$(cat /tmp/activity_log.md)
-  activity=$(printf '\n\n<details>\n<summary>🔧 activity — %s tool calls</summary>\n\n%s\n\n</details>' "$entries" "$log")
-fi
-
+# $activity (the run report: tool calls + tokens + $ cost) was built once near the top, so every
+# dev-agent exit path (no-changes, PR-open-failed, normal) appends it to the single reply comment.
 # One PR per run: publish ONLY this run's own branch ($BRANCH), never sibling
 # ai/issue-N-* branches. This removes the multi-PR ambiguity that left the
 # activity log stranded on the triggering issue instead of the PR thread.