Stop the Stop hook from loading the whole transcript into memory every turn

.claude-plugin/marketplace.json

@@ -10,7 +10,7 @@
       "name": "warp",
       "description": "Native Warp notifications when Claude completes tasks or needs input",
       "source": "./plugins/warp",
-      "version": "2.4.0",
+      "version": "2.4.1",
       "category": "productivity",
       "tags": ["notifications", "terminal", "warp"]
     },

README.md

@@ -49,7 +49,7 @@ Payloads include a protocol version negotiated between the plugin and Warp (`min
 
 The plugin registers lifecycle hooks including:
 - **SessionStart** — emits the plugin version and a welcome system message
-- **Stop** — reads the transcript to extract your prompt and Claude's response, then sends a task-complete notification that also reports how many background tasks and scheduled wakeups are still pending, so Warp can tell a finished session from one waiting on background work
+- **Stop** — reads the end of the transcript to extract your prompt and Claude's response, then sends a task-complete notification that also reports how many background tasks and scheduled wakeups are still pending, so Warp can tell a finished session from one waiting on background work
 - **Notification** (`idle_prompt`, `agent_needs_input`) — fires when Claude is waiting for user input
 - **PermissionRequest** — fires when Claude wants to run a tool, includes the tool name and a preview of its input
 - **UserPromptSubmit** — fires when you submit a prompt, signaling the session is active again

plugins/warp/.claude-plugin/plugin.json

@@ -1,7 +1,7 @@
 {
   "name": "warp",
   "description": "Warp terminal integration for Claude Code - native notifications, and more to come",
-  "version": "2.4.0",
+  "version": "2.4.1",
   "author": {
     "name": "Warp",
     "url": "https://warp.dev"

plugins/warp/scripts/legacy/on-stop.sh

@@ -3,6 +3,7 @@
 # Sends a Warp notification when Claude completes a task
 
 SCRIPT_DIR="$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)"
+source "$SCRIPT_DIR/../transcript-tail.sh"
 
 # Read hook input from stdin
 INPUT=$(cat)
@@ -15,16 +16,18 @@ MSG="Task completed"
 
 # Try to extract prompt and response from the transcript (JSONL format)
 if [ -n "$TRANSCRIPT_PATH" ] && [ -f "$TRANSCRIPT_PATH" ]; then
-    # Get the first user prompt
-    PROMPT=$(jq -rs '
-        [.[] | select(.type == "user")] | first | .message.content // empty
+    # Get the first user prompt. Stream records and stop at the first match,
+    # so memory stays at one record however long the transcript is.
+    PROMPT=$(jq -rn '
+        first(inputs | select(.type == "user")) | .message.content // empty
     ' "$TRANSCRIPT_PATH" 2>/dev/null)
 
-    # Get the last assistant response
-    RESPONSE=$(jq -rs '
+    # Get the last assistant response from a bounded tail of the transcript
+    RESPONSE_FILTER='
         [.[] | select(.type == "assistant" and .message.content)] | last |
         [.message.content[] | select(.type == "text") | .text] | join(" ")
-    ' "$TRANSCRIPT_PATH" 2>/dev/null)
+    '
+    RESPONSE=$(transcript_tail "$TRANSCRIPT_PATH" "$TRANSCRIPT_TAIL_BYTES" | jq -rs "$RESPONSE_FILTER" 2>/dev/null)
 
     if [ -n "$PROMPT" ] && [ -n "$RESPONSE" ]; then
         # Truncate prompt to 50 chars

plugins/warp/scripts/on-stop.sh

@@ -12,6 +12,7 @@ if ! should_use_structured; then
 fi
 
 source "$SCRIPT_DIR/build-payload.sh"
+source "$SCRIPT_DIR/transcript-tail.sh"
 
 # Read hook input from stdin
 INPUT=$(cat)
@@ -36,7 +37,10 @@ if [ -n "$TRANSCRIPT_PATH" ] && [ -f "$TRANSCRIPT_PATH" ]; then
     # containing {type:"text"} blocks. Tool-result messages have content arrays
     # containing only {type:"tool_result"} blocks. We filter to messages that
     # have at least one "text" block (or are a plain string).
-    QUERY=$(jq -rs '
+    #
+    # Both values sit near the end, so read a bounded tail instead of the whole
+    # transcript, and retry with a larger one only when no prompt is in the first.
+    QUERY_FILTER='
         [
             .[] | select(.type == "user") |
             if .message.content | type == "string" then .
@@ -48,13 +52,19 @@ if [ -n "$TRANSCRIPT_PATH" ] && [ -f "$TRANSCRIPT_PATH" ]; then
         then [.message.content[] | select(.type == "text") | .text] | join(" ")
         else .message.content // empty
         end
-    ' "$TRANSCRIPT_PATH" 2>/dev/null)
+    '
+    QUERY=$(transcript_tail "$TRANSCRIPT_PATH" "$TRANSCRIPT_TAIL_BYTES" | jq -rs "$QUERY_FILTER" 2>/dev/null)
+    if [ -z "$QUERY" ] && transcript_larger_than "$TRANSCRIPT_PATH" "$TRANSCRIPT_TAIL_BYTES"; then
+        QUERY=$(transcript_tail "$TRANSCRIPT_PATH" "$TRANSCRIPT_TAIL_MAX_BYTES" | jq -rs "$QUERY_FILTER" 2>/dev/null)
+    fi
 
-    # Get the last assistant response
-    RESPONSE=$(jq -rs '
+    # Get the last assistant response. The last assistant record is always at
+    # the very end, so the first window is enough.
+    RESPONSE_FILTER='
         [.[] | select(.type == "assistant" and .message.content)] | last |
         [.message.content[] | select(.type == "text") | .text] | join(" ")
-    ' "$TRANSCRIPT_PATH" 2>/dev/null)
+    '
+    RESPONSE=$(transcript_tail "$TRANSCRIPT_PATH" "$TRANSCRIPT_TAIL_BYTES" | jq -rs "$RESPONSE_FILTER" 2>/dev/null)
 
     # Truncate for notification display
     if [ -n "$QUERY" ] && [ ${#QUERY} -gt 200 ]; then

plugins/warp/scripts/transcript-tail.sh

@@ -0,0 +1,33 @@
+#!/bin/bash
+# Reads only the end of a Claude Code transcript.
+#
+# Transcripts grow for the whole session and can reach gigabytes. Slurping the
+# whole file with `jq -s` costs about three times its size in memory at every
+# turn end, while the last prompt and response sit within the final few
+# hundred KB. Reading a bounded tail keeps the Stop hook's memory flat.
+#
+# Usage:
+#   source "$SCRIPT_DIR/transcript-tail.sh"
+#   transcript_tail "$TRANSCRIPT_PATH" "$TRANSCRIPT_TAIL_BYTES" | jq -rs '...'
+
+# Window to read, and the larger one to retry with when the last prompt
+# is further back (a long autonomous turn with big tool results).
+TRANSCRIPT_TAIL_BYTES=4194304
+TRANSCRIPT_TAIL_MAX_BYTES=33554432
+
+# Prints the last $2 bytes of transcript $1, dropping the partial line the cut
+# lands in. Transcripts are JSONL, so every remaining line is a whole record.
+transcript_tail() {
+    local path="$1" bytes="$2"
+    if [ "$(wc -c < "$path")" -gt "$bytes" ]; then
+        tail -c "$bytes" "$path" | tail -n +2
+    else
+        cat "$path"
+    fi
+}
+
+# Returns 0 if transcript $1 is larger than $2 bytes, so a bigger window could
+# find something the smaller one missed.
+transcript_larger_than() {
+    [ "$(wc -c < "$1")" -gt "$2" ]
+}

plugins/warp/tests/test-hooks.sh

@@ -56,7 +56,7 @@ MARKETPLACE_VERSION=$(jq -r '.plugins[] | select(.name == "warp") | .version' \
     "$REPO_DIR/.claude-plugin/marketplace.json")
 NOTIFICATION_MATCHER=$(jq -r '.hooks.Notification[0].matcher' "$PLUGIN_DIR/hooks/hooks.json")
 
-assert_eq "plugin version bumped" "2.4.0" "$PLUGIN_VERSION"
+assert_eq "plugin version bumped" "2.4.1" "$PLUGIN_VERSION"
 assert_eq "marketplace version matches plugin" "$PLUGIN_VERSION" "$MARKETPLACE_VERSION"
 assert_eq "notification matcher includes input-required events" \
     "idle_prompt|agent_needs_input" \
@@ -320,6 +320,57 @@ for HOOK in on-permission-request.sh on-prompt-submit.sh on-post-tool-use.sh; do
     assert_eq "$HOOK exits 0 without protocol version" "0" "$?"
 done
 
+echo ""
+echo "--- Transcript tail ---"
+
+source "$SCRIPT_DIR/transcript-tail.sh"
+TAIL_TMP=$(mktemp -d)
+trap 'rm -rf "$TAIL_TMP"' EXIT
+
+prompt_line() { jq -nc --arg t "$1" '{type:"user",message:{role:"user",content:$t}}'; }
+reply_line() { jq -nc --arg t "$1" '{type:"assistant",message:{role:"assistant",content:[{type:"text",text:$t}]}}'; }
+# About 1 MB of tool results, the bulk of a long session's transcript.
+FILLER=$(jq -nc --arg c "$(head -c 1000 /dev/zero | tr '\0' x)" \
+    '{type:"user",message:{role:"user",content:[{type:"tool_result",tool_use_id:"t1",content:$c}]}}')
+filler_mb() { yes "$FILLER" | head -n $(($1 * 1000)); }
+
+# Runs on-stop.sh on a transcript and prints the structured payload it emits.
+run_stop_hook() {
+    local seq
+    seq=$(jq -nc --arg p "$1" '{session_id:"s1",cwd:"/tmp/proj",transcript_path:$p}' \
+        | WARP_CLI_AGENT_PROTOCOL_VERSION=1 WARP_CLIENT_VERSION=v0.2026.09.30.08.29.stable_01 \
+          CLAUDE_CODE_VERSION=2.1.283 bash "$SCRIPT_DIR/on-stop.sh" 2>/dev/null \
+        | jq -r '.terminalSequence // empty' 2>/dev/null)
+    seq=${seq#*warp://cli-agent;}
+    printf '%s' "${seq%$'\a'}"
+}
+
+{ prompt_line "first prompt"; reply_line "first reply"; } > "$TAIL_TMP/small.jsonl"
+assert_eq "small transcript is read whole" "2" "$(transcript_tail "$TAIL_TMP/small.jsonl" "$TRANSCRIPT_TAIL_BYTES" | wc -l | tr -d ' ')"
+
+{ prompt_line "old prompt"; filler_mb 6; prompt_line "recent prompt"; reply_line "recent reply"; } > "$TAIL_TMP/large.jsonl"
+FIRST_LINE=$(transcript_tail "$TAIL_TMP/large.jsonl" "$TRANSCRIPT_TAIL_BYTES" | head -n 1)
+echo "$FIRST_LINE" | jq -e . >/dev/null 2>&1
+assert_eq "tail starts on a whole record" "0" "$?"
+TAIL_SIZE=$(transcript_tail "$TAIL_TMP/large.jsonl" "$TRANSCRIPT_TAIL_BYTES" | wc -c | tr -d ' ')
+assert_eq "tail stays within the window" "true" "$([ "$TAIL_SIZE" -le "$TRANSCRIPT_TAIL_BYTES" ] && echo true || echo false)"
+PAYLOAD=$(run_stop_hook "$TAIL_TMP/large.jsonl")
+assert_json_field "stop query from the tail" "$PAYLOAD" ".query" "recent prompt"
+assert_json_field "stop response from the tail" "$PAYLOAD" ".response" "recent reply"
+
+{ prompt_line "far prompt"; filler_mb 10; reply_line "far reply"; } > "$TAIL_TMP/far.jsonl"
+assert_json_field "prompt beyond the first window is found" "$(run_stop_hook "$TAIL_TMP/far.jsonl")" ".query" "far prompt"
+
+# The Stop hook must not hold the whole transcript in memory. Linux enforces
+# ulimit -v; skip where it does not (macOS).
+if (ulimit -v 131072) 2>/dev/null; then
+    { filler_mb 100; prompt_line "bounded prompt"; reply_line "bounded reply"; } > "$TAIL_TMP/huge.jsonl"
+    PAYLOAD=$(ulimit -v 131072; run_stop_hook "$TAIL_TMP/huge.jsonl")
+    assert_json_field "100 MB transcript fits in 128 MB" "$PAYLOAD" ".query" "bounded prompt"
+else
+    echo "  - memory bound check skipped (ulimit -v not enforced here)"
+fi
+
 # --- Summary ---
 
 echo ""