agent-canvas-environment

v2026.09.24
openhands/extensions00

Work effectively inside a local Agent Canvas environment, including local agent-server auth, frontend/backend port discovery, safe workspace hygiene, and delegating work to a new local conversation through POST /api/conversations.

GitHub
Install command
npx skhub add openhands/agent-canvas-environment
Markdown
SKILL.md

Agent Canvas Environment

Use this skill when running inside or alongside a local Agent Canvas stack, especially when the user asks to inspect the local backend, create or monitor local conversations, or delegate work to another local conversation.

Core rules

  • Treat the local Agent Canvas backend as an agent-server API, usually http://localhost:8001.
  • Treat the local UI as a separate frontend, usually http://localhost:8000.
  • Do not print session API keys. Pass them directly in X-Session-API-Key.
  • Trust any runtime-services block or explicit user-provided host over default ports.
  • Before mutating a repository, check git status -sb. If a worktree has unrelated changes, use a separate worktree or clone.
  • When delegating, write a self-contained prompt. The new conversation does not inherit the current chat context.

Find the session key

Use the first available value, without echoing it:

KEY="${SESSION_API_KEY:-${OH_SESSION_API_KEYS_0:-${LOCAL_BACKEND_API_KEY:-}}}"
if [ -z "$KEY" ] && [ -f "$HOME/.openhands/agent-canvas/api-key.txt" ]; then
  KEY="$(tr -d '\n' < "$HOME/.openhands/agent-canvas/api-key.txt")"
fi
test -n "$KEY" || { echo "No Agent Canvas session API key found" >&2; exit 1; }

Validate backend access:

curl -sS -o /tmp/agent-canvas-conversations.json -w '%{http_code}\n' \
  -H "X-Session-API-Key: $KEY" \
  http://localhost:8001/api/conversations/search

HTTP 200 means the backend and key work.

Delegate to a local conversation

Use POST /api/conversations with:

  • the encrypted agent_settings from GET /api/settings (with X-Expose-Secrets: encrypted), which carries the real Fernet-encrypted llm.api_key, the existing agent_context, and the agent kind — so you never handle plaintext credentials and you don't drop the caller's skill/context config
  • secrets_encrypted: true so the agent-server decrypts that api_key server-side
  • the exec tool set merged into agent_settings.tools (and task_tool_set when you enable sub-agents)
  • tool_module_qualnames for any non-SDK tools (e.g. canvas_ui)
  • agent_context.load_public_skills/load_user_skills/load_project_skills set to true if the delegated agent should inherit bundled/user/project skills
  • a fresh absolute workspace directory
  • initial_message.run: true
  • worktree: false when the workspace is already isolated

Credential handling — important

GET /api/settings (default) masks every credential — llm.api_key comes back as the literal string "**********". If you forward that verbatim, the new conversation authenticates with the placeholder and fails immediately with LLMAuthenticationError (You must provide an API key).

The supported way to obtain forwardable credentials is the X-Expose-Secrets: encrypted request header. With it, /api/settings returns the real llm.api_key as a Fernet-encrypted token (starts with gAAAAA) intended to be sent back to the server with secrets_encrypted: true; the agent-server's decrypt_incoming_llm_secrets decrypts it server-side. Do not read ~/.openhands/profiles/*.json directly — that is brittle (the caller may not share the backend's home directory, active_profile may be null, the profile store may live elsewhere).

Two working approaches:

  1. agent_profile_id (simplest, but no tools) — send only agent_profile_id: "<uuid>" (from GET /api/agent-profiles → the profile whose id equals active_agent_profile_id from /api/settings). The server resolves the LLM key + agent kind from the profile. Mutually exclusive with agent/agent_settings, and the openhands agent-profile schema forbids tools/include_default_tools, so the conversation gets zero exec tools this way. Use only when the task needs no tools.

  2. Encrypted agent_settings (full tools, preserves context) — start from the encrypted /api/settings agent_settings payload, drop schema_version and mcp_config (to avoid MCP-connection failures at creation time), merge in the exec tool set and load_*_skills flags, and send with secrets_encrypted: true. This is the pattern for real delegated work.

Template (full tools, preserves context):

set -euo pipefail

BASE="${AGENT_CANVAS_BACKEND:-http://localhost:8001}"
KEY="${SESSION_API_KEY:-${OH_SESSION_API_KEYS_0:-${LOCAL_BACKEND_API_KEY:-}}}"
if [ -z "$KEY" ] && [ -f "$HOME/.openhands/agent-canvas/api-key.txt" ]; then
  KEY="$(tr -d '\n' < "$HOME/.openhands/agent-canvas/api-key.txt")"
fi
test -n "$KEY" || { echo "No Agent Canvas session API key found" >&2; exit 1; }

WORKDIR="${WORKDIR:-$HOME/workspace/delegated/$(date +%Y%m%d-%H%M%S)}"
mkdir -p "$WORKDIR"

# Fetch the agent_settings with ENCRYPTED secrets exposed. This returns the
# real llm.api_key as a Fernet token (gAAAAA...) plus the existing
# agent_context/agent kind, so we preserve the caller's config and never
# handle plaintext credentials.
SETTINGS_JSON="$(curl -sS -H "X-Session-API-Key: $KEY" -H "X-Expose-Secrets: encrypted" "$BASE/api/settings")"

PROMPT='Write a complete, task-specific prompt here. Include repo, branch, constraints, validation, and expected report.'

PAYLOAD="$(jq -n --argjson settings "$SETTINGS_JSON" --arg prompt "$PROMPT" --arg workdir "$WORKDIR" '
  # Start from the encrypted agent_settings so llm.api_key (Fernet token),
  # agent_kind, and agent_context are preserved. Drop schema_version and
  # mcp_config (MCP servers can fail to connect at creation time; the profile
  # can be re-resolved later if needed).
  def base_agent_settings:
    ($settings.agent_settings // {})
    | del(.schema_version)
    | del(.mcp_config);

  # Merge the exec tool set into the existing tools list. Include task_tool_set
  # when sub-agents are enabled — enable_sub_agents alone does not expose the
  # delegation tool; Agent Canvas adds task_tool_set for that.
  def with_tools:
    .tools = ((.tools // []) + [
      {name: "terminal", params: {}},
      {name: "file_editor", params: {}},
      {name: "task_tracker", params: {}},
      {name: "browser_tool_set", params: {}},
      {name: "canvas_ui", params: {}}
    ] + (if .enable_sub_agents then [{name: "task_tool_set", params: {}}] else [] end)
    | unique_by(.name));

  # Preserve the existing agent_context and enable skill loading for the
  # delegated agent (defaults are false, so set these explicitly).
  def with_skill_loading:
    .agent_context = ((.agent_context // {}) + {
      load_public_skills: true,
      load_user_skills: true,
      load_project_skills: true
    });

  ($settings.conversation_settings // {}) as $conv |
  {
    secrets_encrypted: true,
    agent_settings: (base_agent_settings | with_tools | with_skill_loading),
    tool_module_qualnames: { canvas_ui: "canvas_ui_tool" },
    workspace: {kind: "LocalWorkspace", working_dir: $workdir},
    confirmation_policy: {kind: "NeverConfirm"},
    # Delegated tasks usually need more than the SDK default of 80 iterations;
    # default to the caller's conversation_settings value (1000 in Agent Canvas)
    # so long-running tasks aren't cut off prematurely. Override per-task if needed.
    max_iterations: (($conv.max_iterations // 1000) | if . == null then 1000 else . end),
    stuck_detection: true,
    autotitle: true,
    worktree: false,
    initial_message: {
      role: "user",
      content: [{type: "text", text: $prompt}],
      run: true
    }
  }
')"

curl -sS -X POST "$BASE/api/conversations" \
  -H "Content-Type: application/json" \
  -H "X-Session-API-Key: $KEY" \
  --data-binary "$PAYLOAD" | jq '{id, title, execution_status, workspace}'

Verify the new conversation actually has tools and is running (not errored):

CID="<conversation_id>"
curl -sS -H "X-Session-API-Key: $KEY" "$BASE/api/conversations/$CID" \
  | jq '{execution_status, tools: [.agent.tools[]?.name]}'
curl -sS -H "X-Session-API-Key: $KEY" "$BASE/api/conversations/$CID/events/search?limit=20" \
  | jq '[.events[]? | select(.kind=="ConversationErrorEvent") | .code] // []'

execution_status should be running/idle/finished (not error), tools should list the exec tools, and there should be no ConversationErrorEvent.

If MCP servers configured in the profile are unreachable, conversation creation can fail with MCP Connection Failure; the template drops mcp_config from the forwarded agent_settings to avoid that.

Report both links:

  • UI: http://localhost:8000/conversations/<conversation_id>
  • API: http://localhost:8001/api/conversations/<conversation_id>

Monitor a delegated conversation

CID="<conversation_id>"
curl -sS -H "X-Session-API-Key: $KEY" "$BASE/api/conversations/$CID" \
  | jq '{id, title, execution_status, updated_at, workspace, agent_kind: .agent.kind, current_model_id, current_model_name}'

curl -sS -H "X-Session-API-Key: $KEY" "$BASE/api/conversations/$CID/events/search?limit=20" \
  | jq '.events // .items // .'

Terminal statuses commonly include idle, running, finished, error, stuck, and stopped.

Prompt checklist for delegation

Include:

  • repository owner/name and local path if relevant
  • branch, PR, issue, or Linear ticket identifiers
  • current status and known blockers
  • exact files or subsystems in scope
  • dirty-worktree warnings and paths not to touch
  • whether to push, open a PR, or only report
  • checks/tests to run
  • expected final report format

Do not rely on the new conversation knowing anything from the current thread.

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Version
Latest version metadata

Version

v2026.09.24

Published

Sep 24, 2026

Category

Uncategorized

License

MIT

Source path

skills/agent-canvas-environment

Default branch

main

Latest commit

f02d3aa

Tree SHA

f3a3b25