MemForge: Portable, agent-neutral persistent memory format for AI coding agents (v0.5.0)

MemForge is a portable, agent-neutral persistent memory format for AI coding agents (Claude Code, Cursor, Aider, Continue.dev, and others). The format describes a folder of typed markdown files with a single index, optionally organized into rollup subfolders. v0.5.0 extends the v0.4.0 single-operator multi-agent foundation to multi-identity team-scale memory with cryptographic attribution and a real-time messaging substrate (WebSocket). Eight new normative sections cover multi-identity primitives (operator long-lived keys + agent ephemeral keys; required identity + signature frontmatter), cryptographic attribution (GPG default; signing-time-aware verification with first_seen_at clock-skew guard), operator identity + cross-store references (UUIDv7 + fail-closed signed registry + content-hash-anchored cache), messaging adapter contract (WebSocket; sender-uid + sender-sequence + signed checkpoints; receiver-state file shape; wss:// + per-operator strong auth mandatory), key lifecycle + revocation (GPG-signed revoke commits + revoked_at clock-skew guard; sparse-checkout TOFU + fast-forward-only fallback; recovery-secret content integrity via SHA256 in registry; 24-hour cool-down on key rotation), security considerations (eleven boundary statements), known limitations (residual non-BLOCKER refinements), and a cross-element surface map. v0.5.0 ships with no BLOCKER-class known limitations. This deposit bundles the canonical specification (SPEC.md), the controlled-vocabulary taxonomy (taxonomy.yaml), the known-limitations document (v0.5.0-known-limitations.md), the changelog through v0.5.0, the Apache-2.0 license, and a bundle README. The Python reference implementation (audit, link rewriter, frontmatter backfill, etc.) ships separately as ildan-memforge on PyPI; the v0.5.1 patch will add reference CLI binaries for the new v0.5.0 operator-side flows. Spec is licensed Apache-2.0 (same as the reference implementation). Prose in this bundle is CC-BY-4.0.