chore: version 2.0.0-alpha.6 — companion on Claude CLI subprocess (Max subscription)

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

CHANGELOG.md

@@ -3,6 +3,32 @@
 All notable changes to Void 2.0 are documented here.
 Format: [Keep a Changelog](https://keepachangelog.com).
 
+## [2.0.0-alpha.6] — 2026-06-01
+
+### Changed (Plan 5b: companion backend → Claude CLI subprocess)
+
+- **Companion model backend switched from the Anthropic API to the `claude`
+  CLI subprocess**, authenticated by the owner's **Claude Max subscription**
+  (no API key — the Agent SDK can't use subscription auth headlessly, and Max
+  doesn't issue API keys). Mirrors Void 1.0's `lib/agent.js`: spawn `claude`
+  with `ANTHROPIC_API_KEY`/`ANTHROPIC_AUTH_TOKEN` stripped so it uses the
+  logged-in subscription. The CLI owns the agentic loop; the four companion
+  tools are exposed to it via a local **stdio MCP server** (`lib/mcp/`).
+- `lib/ai/claude_cli.js` — spawns `claude --print --output-format stream-json
+  --include-partial-messages --append-system-prompt … (--session-id | --resume)
+  --mcp-config … --strict-mcp-config --tools … --allowedTools …`, maps stream-json
+  → `{delta,tool,tool_result,result,error}`. Prompt fed via **stdin** (variadic
+  `--tools` would eat a positional). Multi-turn continuity via `--resume`.
+- `lib/mcp/companion-stdio.js` — stdio MCP server re-exposing `companionRegistry`;
+  per-turn Space/agent context passed via env in the `--mcp-config`.
+- `propose_change` now stamps the current Space onto created space-scoped
+  entities (model can't know the Space uuid).
+- CT 311 runs the `claude` CLI (logged in as `void`, `HOME=/var/lib/void`).
+- Built-in CLI tools (Bash/Read/Write/…) disabled via `--tools`; the companion
+  has only the four `mcp__void__*` tools.
+- The old `@anthropic-ai/sdk` API-key path (`lib/ai/anthropic.js`, `runTurn`)
+  is retained in-tree but no longer the companion's execution path.
+
 ## [2.0.0-alpha.5] — 2026-06-01
 
 ### Added (Plan 5: Companion chat)