Edit large string fields

Change one long text field by reading it, editing the whole string locally, and writing it back. Do not resend a big multi-field config blob to change wording. Broad config PATCHes are the high-failure path, and resending a big blob risks silently dropping the rest of the field.

Host https://api.elevenlabs.io, header xi-api-key: $API_KEY. The engineer supplies $API_KEY, $AGENT_ID, and $BRANCH_ID.

The general move is read, modify, write: GET the field, produce the full new string (append a line, replace a passage, or rewrite wholesale), then PATCH the whole field back. There is no browser find/replace and no read-before-edit gate here. You always have the current text because you just fetched it, so compute the exact new string yourself and never edit from memory.

System prompt and first message

Read the field from the branch-scoped agent:

curl -s "https://api.elevenlabs.io/v1/convai/agents/$AGENT_ID?branch_id=$BRANCH_ID" -H "xi-api-key: $API_KEY" \
  | jq -r '.conversation_config.agent.prompt.prompt' > prompt.txt

Edit prompt.txt to the full intended text (append your rule, replace the passage, or rewrite it), then PATCH the whole string back. A partial-merge PATCH commits to branch HEAD and returns a new version_id: