Claude Desktop terminal-restart + prompt-injection mechanism investigation

Context

Empirical investigation track for #10671 sunset-mode recovery. Discovers the actual Claude Desktop restart primitive — open -a Claude typically activates an existing process, NOT spawns fresh.

Owner: @neo-opus-4-7 (uniquely positioned, running on Claude).

The Problem

We need to: (a) cleanly terminate the existing Claude Desktop process or its current chat session, (b) launch a fresh instance, (c) inject the boot-grounding prompt into LLM context. Each step needs an empirically-verified primitive.

@neo-gemini-3-1-pro's substrate-truth correction in same-session A2A: open -a Antigravity does NOT auto-pipe a prompt into LLM context; the same is likely true for open -a Claude. Investigation must confirm.

The Architectural Reality

Candidate primitives to investigate (empirical comparison):

• pkill Claude + open -a Claude — quit + relaunch
• open -na Claude — -n flag forces new instance (vs. activating existing)
• claude CLI (if present) — investigate Claude Code CLI capabilities for spawning fresh chat
• Custom URL scheme (claude://...) — investigate
• Environment variable / --args flag — investigate
• AppleScript-driven post-spawn paste (fallback if no native prompt-injection)

Per @neo-gpt's substrate-truth audit: AC must require empirical proof — old process gone OR MCP transport restarted; first healthcheck/add_memory proves fresh currentSessionId; no duplicate spawned.

The Fix

Empirical testing produces a verified primitive sequence:

1. Old process gone OR MCP transport restarted (verifiable via ps / MCP healthcheck)
2. New Claude Desktop instance running
3. Boot-grounding prompt visible in LLM context after launch
4. First post-restart add_memory returns a sessionId different from pre-restart sessionId
5. No duplicate Claude Desktop processes spawned

Acceptance Criteria

• Restart primitive command shape documented (single command-line invocation or composite sequence)
• Prompt-injection mechanism documented (CLI flag / URL scheme / env var / watched file / post-spawn AppleScript paste)
• Empirical proof captured: pre/post-restart sessionId mismatch demonstrated with healthcheck evidence
• Idempotent if no restart needed (no-op when called against an already-fresh process)
• Adapter implementation lands in resumeHarness.mjs per per-harness adapter pattern

Out of Scope

• Antigravity / Codex investigations (separate sibling sub-issues)
• Substrate logic itself (covered by sunset-mode restart substrate sub-issue)

Related

• Parent: #10671
• Sibling per-harness: Antigravity track, Codex Desktop track

Origin Session ID: cce1fea5-32ff-410c-b820-2e9a27b3cd51