> ## Documentation Index
> Fetch the complete documentation index at: https://prism.ntecdev.ai/llms.txt
> Use this file to discover all available pages before exploring further.

# ADR-8: New MCP verb `hd_exec` — symmetric handoff pickup for cross-agent continuity

> Add a new MCP verb `hd_exec` (short for 'handoff execute' / 'handoff pickup'). Symmetric counterpart to prism_wrap: prism_wrap closes a session, hd_exec opens o

<Info>**Status:** `accepted` · **ADR-8** · Filed 2026-04-17</Info>

## Decision

Add a new MCP verb `hd_exec` (short for 'handoff execute' / 'handoff pickup'). Symmetric counterpart to prism\_wrap: prism\_wrap closes a session, hd\_exec opens one for an inherited thread. Behavior: (1) resolve PID from project\_dir match or prompt; (2) fetch last prism\_handoff doc for this PID; (3) return structured payload with status\_card (last handoff author+timestamp, focus field, next\_agent), recent session deltas, TODOs tagged to the handoff focus, ADRs in the recent window, retros for current phase, any Ring 4 drift warnings; (4) set a session marker so the subsequent prism\_wrap knows this was a handoff pickup (enables Ring 4 enforcement: 'you picked up a handoff but didn't address the focus items'). CC and Codex should surface hd\_exec as a lightweight entry point — a single verb/command agents type or run on session start when continuing another agent's work.

## Rationale

Today prism\_handoff writes the handoff doc but there is no symmetric verb to READ it as the pickup ritual. Agents continuing another agent's work must manually call prism\_start + search past chats + reconstruct the thread. hd\_exec makes cross-agent continuity a single tool call. The session-marker semantics matter: without it, Ring 4 enforcement cannot distinguish 'fresh session on this project' from 'picking up a handoff' — and those have different accounting obligations. This is the verb that operationalizes the shared-memory thesis of Prism.

## Alternatives Considered

Overload prism\_handoff with a mode parameter (handoff write-mode vs read-mode) — conflates two verbs with opposite directions. Use prism\_start for handoff pickup — but prism\_start is project-level; hd\_exec is handoff-level (pick up a specific thread, not just project state). Make it a CC slash-command only — but then Codex and other MCP clients can't use it.