[Bug] Task tool missing agent ID in completed agent responses

I'm on 2.0.33 on Windows and this isn't working. Frustrating. No agentId

Come on!!Fix it!!!!!Fix it!!!!!Fix it!!!!!

Resumption is a key feature for making subagents useful, I'm on 2.0.51 and encountering this on Linux (WSL2). Please escalate the priority of this.

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A very hacky work-around that shouldn't be needed (Linux, but if you get the idea you could re-create):
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Resume Agents

Agent Session Tracking

Always track agent invocations:

• What: name, agentId, brief task description.
• Where: .claude/sessions.md.

What to record:

• Name: Elliot, Jet, Morty, Rick
• ID: 8-char hex
• Context: Brief description of agent task/prompt

Getting agentId

CRITICAL Capture timing matters: Capture immediately after invocation. Once you invoke a second agent, the first agent's ID becomes difficult to retrieve.

Project command over-ride: Project CLAUDE.md commands over-ride these generic instructions and provide the full path without having to find the {project-hash}.

Capture Patterns

Generic command (replace {project-hash} with actual folder):

Single agent

ls -t ~/.claude/projects/{project-hash}/agent-*.jsonl | head -1 | xargs jq -r '.agentId' | uniq

Multi agent

1. Invoke N agents in parallel with {name}: prefixes:

• "Rick: Perform code review: X"
• "Morty: design schema for Y"

1. IMMEDIATELY get names and agentIds with:

for id in $(ls -t ~/.claude/projects/{project-hash}/agent-*.jsonl | head -{number-of-agents} | xargs jq -r '.agentId' | uniq); do
  echo -n "$id: "
  jq -r ".message.content" ~/.claude/projects/{project-hash}/agent-${id}.jsonl | head -1 | cut -d: -f1
done

Example output:

20b05857: Rick
3a22e872: Morty

Resumption: Agent targeted by ID, {name} not needed.

Resume agent-{agentId}: "Continue to next phase."

For anyone looking to enable agent resumption via claude-code (requires jq):

# post-task.sh
#!/usr/bin/env bash
# PostToolUse hook for agentId tracking
# Injects active agent information into Claude's context after Task tool invocations

set -euo pipefail

# Determine plugin root directory (same as session-start.sh)
# CLAUDE_PLUGIN_ROOT is provided by Claude Code, but we compute it as fallback
SCRIPT_DIR="$(cd "$(dirname "${BASH_SOURCE[0]:-$0}")" && pwd)"
PLUGIN_ROOT="${CLAUDE_PLUGIN_ROOT:-$(cd "${SCRIPT_DIR}/.." && pwd)}"

# Read hook data from stdin
HOOK_DATA=$(cat)

# Only process Task tool invocations
TOOL_NAME=$(echo "$HOOK_DATA" | jq -r '.tool_name')
if [[ "$TOOL_NAME" != "Task" ]]; then
  exit 0
fi

# Extract agent information
AGENT_ID=$(echo "$HOOK_DATA" | jq -r '.tool_response.agentId // null')
SUBAGENT_TYPE=$(echo "$HOOK_DATA" | jq -r '.tool_input.subagent_type')
RESUME=$(echo "$HOOK_DATA" | jq -r '.tool_input.resume // null')

# Only process if we have a valid agentId
if [[ "$AGENT_ID" != "null" && -n "$AGENT_ID" ]]; then

  # === Context Injection ===
  # Determine if this is a new agent or resumed agent
  if [[ "$RESUME" == "null" ]]; then
    MSG="Active agent: $AGENT_ID ($SUBAGENT_TYPE)"
  else
    MSG="Resumed agent: $AGENT_ID ($SUBAGENT_TYPE)"
  fi

  # Inject context into Claude's conversation
  jq -n --arg msg "$MSG" '{
    hookSpecificOutput: {
      hookEventName: "PostToolUse",
      additionalContext: ("<system-reminder>\($msg)</system-reminder>")
    }
  }'
fi

exit 0

your .claude/settings.json:

{
...
  "hooks": {
...
    "PostToolUse": [
      {
        "matcher": "Task",
        "hooks": [
          {
            "type": "command",
            "command": "<path-to-script>/post-task.sh"
          }
        ]
      }
    ]
  }
}

Added agentId to the model prompt (and it should already be part of the cli UI):

<img width="708" height="252" alt="Image" src="https://github.com/user-attachments/assets/b54f143f-cb5a-4d0f-8abc-7bb67d639cd9" />

<img width="798" height="114" alt="Image" src="https://github.com/user-attachments/assets/9f478f75-25ac-4c57-920e-b17be0b8d13e" />

Might take a day or two to deploy to npm.

Added agentId to the model prompt (and it should already be part of the cli UI): <img alt="Image" width="708" height="252" src="https://private-user-images.githubusercontent.com/213701943/523482002-b54f143f-cb5a-4d0f-8abc-7bb67d639cd9.png?jwt=eyJ0eXAiOiJKV1QiLCJhbGciOiJIUzI1NiJ9.eyJpc3MiOiJnaXRodWIuY29tIiwiYXVkIjoicmF3LmdpdGh1YnVzZXJjb250ZW50LmNvbSIsImtleSI6ImtleTUiLCJleHAiOjE3NjU1NDAxMjcsIm5iZiI6MTc2NTUzOTgyNywicGF0aCI6Ii8yMTM3MDE5NDMvNTIzNDgyMDAyLWI1NGYxNDNmLWNiNWEtNGQwZi04YWJjLTdiYjY3ZDYzOWNkOS5wbmc_WC1BbXotQWxnb3JpdGhtPUFXUzQtSE1BQy1TSEEyNTYmWC1BbXotQ3JlZGVudGlhbD1BS0lBVkNPRFlMU0E1M1BRSzRaQSUyRjIwMjUxMjEyJTJGdXMtZWFzdC0xJTJGczMlMkZhd3M0X3JlcXVlc3QmWC1BbXotRGF0ZT0yMDI1MTIxMlQxMTQzNDdaJlgtQW16LUV4cGlyZXM9MzAwJlgtQW16LVNpZ25hdHVyZT00ZTJkYmQ5YzlkMWNlZDY4Mzk0ZDczNjVmZmVkNWI4NGVhMTczOWQ1M2IwNDY2OTA3YTRlNzJmZGM1MWUxM2I2JlgtQW16LVNpZ25lZEhlYWRlcnM9aG9zdCJ9.n8VD60Uq4Y8w6jsI94VdSEY2N7fQTIzWC-JUyMLjOi4"> <img alt="Image" width="798" height="114" src="https://private-user-images.githubusercontent.com/213701943/523482045-9f478f75-25ac-4c57-920e-b17be0b8d13e.png?jwt=eyJ0eXAiOiJKV1QiLCJhbGciOiJIUzI1NiJ9.eyJpc3MiOiJnaXRodWIuY29tIiwiYXVkIjoicmF3LmdpdGh1YnVzZXJjb250ZW50LmNvbSIsImtleSI6ImtleTUiLCJleHAiOjE3NjU1NDAxMjcsIm5iZiI6MTc2NTUzOTgyNywicGF0aCI6Ii8yMTM3MDE5NDMvNTIzNDgyMDQ1LTlmNDc4Zjc1LTI1YWMtNGM1Ny05MjBlLWIxN2JlMGI4ZDEzZS5wbmc_WC1BbXotQWxnb3JpdGhtPUFXUzQtSE1BQy1TSEEyNTYmWC1BbXotQ3JlZGVudGlhbD1BS0lBVkNPRFlMU0E1M1BRSzRaQSUyRjIwMjUxMjEyJTJGdXMtZWFzdC0xJTJGczMlMkZhd3M0X3JlcXVlc3QmWC1BbXotRGF0ZT0yMDI1MTIxMlQxMTQzNDdaJlgtQW16LUV4cGlyZXM9MzAwJlgtQW16LVNpZ25hdHVyZT0xMWE5YTU0MTNmMDYzNTlhOTg5ZTdmNzY5N2RlYWE3M2NmNTQ3ZmViMTU3MDUzODI5OTRlYTFiYTg4NTA0YmE5JlgtQW16LVNpZ25lZEhlYWRlcnM9aG9zdCJ9._ZGqeA-Mbid0bLBfkv2CHz6KfJf2ppORyln5MD8pHXA"> Might take a day or two to deploy to npm.

It has been 5 days. I’ve checked the changelog and tried the latest version, but there’s still no update.

<img width="896" height="948" alt="Image" src="https://github.com/user-attachments/assets/0d43d6cd-de69-4d19-9fbe-5a9d8a84a971" />

I don't know if there's an update on this bug. I tested the latest version and it seems that the agentid is only displayed when the agent is reused. Shouldn't it be displayed every time the agent is used?

<img alt="Image" width="896" height="948" src="https://private-user-images.githubusercontent.com/6283862/526186374-0d43d6cd-de69-4d19-9fbe-5a9d8a84a971.png?jwt=eyJ0eXAiOiJKV1QiLCJhbGciOiJIUzI1NiJ9.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.HfNh1ljlWxga_g0YgkhLDjt5F5MRtwOFqeYBRDeCsMk"> I don't know if there's an update on this bug. I tested the latest version and it seems that the agentid is only displayed when the agent is reused. Shouldn't it be displayed every time the agent is used?

@timgu0

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