TierDecay v0.5.0

Every agent, production Linux: the same posterior and the same deterministic
engine now drive OpenAI Codex and Google Antigravity natively, any MCP client
over stdio, and CI pipelines through a health gate.

Added

• OpenAI Codex adapter (install.sh codex): AGENTS.md, four roles in
  .codex/agents/ bound by model_reasoning_effort (xhigh / high /
  medium / low) with matching sandboxes, the MCP advisor in
  .codex/config.toml, a PreToolUse guard on apply_patch and Bash
  scoped to executor roles (.codex/hooks.json), and single-session
  profiles tierdecay-t0…t3.
• Google Antigravity adapter (install.sh antigravity): an always-on
  workspace rule, four subagents in .agents/agents/ (pro for T3/T2,
  flash for T1/T0, executors sandboxed), and .agents/mcp_config.json.
• Shared Agent Skills (core/agent-skills/: tierdecay-routing,
  tierdecay-distill, tierdecay-execution) installed to .agents/skills/
  for both; the installer records co-ownership so uninstalling one target
  keeps them for the other.
• tierdecay mcp: an MCP server over stdio with tierdecay_route,
  tierdecay_rubric, tierdecay_playbook, tierdecay_status,
  tierdecay_export, tierdecay_doctor, and
  tierdecay_validate_observation; tierdecay_record only with
  --allow-ledger-append true. Speaks the stateless 2026-07-28 protocol
  (server/discover, per-request version in _meta, resultType,
  cacheable tools/list, error -32022 with the supported versions) and the
  initialize handshake of 2025-11-25, 2025-06-18, 2025-03-26, and
  2024-11-05.
• tierdecay doctor: read-only health checks (Node version, ledger and
  playbook parse, 150-line cap, world-writable state, MODELS.md, router
  configuration, guard executable, owed bookkeeping, entries without
  epoch:); exit 1 on any failure.
• tierdecay observe --append LEDGER: validated, locked (O_EXCL, stale
  after 30 s, timeout 10 s), duplicate-refusing, fsync + rename ledger
  append that preserves the file mode.
• tierdecay export --format codex|antigravity; --root, --version,
  tierdecay completion --shell bash; documented, stable exit codes.
• OCI image (Dockerfile): distroless nonroot, base images pinned by
  digest, verified in CI read-only and without network.
• GitHub Action (action.yml): uses: alebgl77/tierdecay@v0.5.0 runs
  doctor, writes a job summary, exposes healthy and report.
• Releases: tag-release.yml tags main when package.json carries a new
  version with a CHANGELOG section, after the full CI suite passes on that
  commit; release assets gain a CycloneDX SBOM covered by SHA256SUMS.
• Engineering diagrams (docs/diagrams/: reference architecture, routing
  decision, decay lifecycle) generated by scripts/build-diagrams.js;
  ROADMAP.md; docs/PRODUCTION.md.
• Tests: tests/test-production.js (MCP both eras, concurrent appends,
  locks, doctor, layouts) and tests/test-adapters.js (Codex and
  Antigravity schemas and bindings against the engine); installer and guard
  suites cover the new targets and Codex apply_patch payloads.

Changed

• The guard resolves the project from CLAUDE_PROJECT_DIR, then
  TIERDECAY_PROJECT_DIR, then the working directory, and understands Codex
  apply_patch envelopes; its Codex copy is generated and CI-checked.
• install.sh auto detects .codex/, .agents/rules/, .agents/agents/,
  and the codex, agy, and antigravity binaries; the codex binary now
  selects the native Codex target instead of the generic AGENTS.md.
• core/MODELS.md records the Codex (effort) and Antigravity (pro /
  flash) bindings.
• Dependabot also tracks the container base images.