v0.23.0

localharness becomes genuinely model-agnostic — Gemini and Claude, on
platform $LH credits, from both the CLI and the browser, with no per-user
provider key. Live end-to-end.

Added

• Anthropic backend (second ConnectionStrategy). src/backends/anthropic/
  implements the Claude Messages API behind the same Connection/
  ConnectionStrategy seam as Gemini — the harness is model-agnostic by
  construction. Agent::start_anthropic(AnthropicAgentConfig::new(key)), models
  claude-haiku-4-5-20251001 (default) / claude-sonnet-4-6 / claude-opus-4-8.
  Gated behind a new anthropic Cargo feature — additive (off by default, no new
  deps, default build + Gemini backend untouched). Streaming SSE, tool calling,
  thinking, compaction all mapped to the neutral types; 23 canned-fixture tests.
• Multi-provider credit proxy. The proxy routes by path (Gemini
  /v1beta/models/<m>:<method>, Anthropic /v1/messages), holds both platform
  keys, and meters per-model $LH (Gemini flat; haiku 0.01 / sonnet 0.05 / opus
  0.20). One redeemed-invite balance calls EITHER provider, no provider key;
  BYOK-either is the fallback. Gemini path byte-identical.
• Model selectors. CLI: call --model <id> routes claude-* to the Anthropic
  backend. Browser: a Gemini/Haiku/Sonnet/Opus dropdown in the Agent admin tab
  (src/app/model.rs, persisted to .lh_model); chat.rs branches the session
  to the right backend through the proxy.

Changed

• Shed the "antigravity SDK port" framing. Described as a model-agnostic agent
  SDK (Gemini today; pluggable backends) across lib.rs / README / llms.txt /
  CLAUDE.md / Cargo; content.rs/types.rs reframed as provider-neutral;
  antig::mcp → localharness::mcp.

Fixed

• --as <name> parses anywhere in the arg list (was first-arg only — broke
  probe --deep --as <name>).
• Cross-backend call history keyed per backend (__<target>.<backend>.bin)
  so Gemini/Claude threads to one target don't collide; an incompatible load warns
  and starts fresh instead of failing the call.
• Clean fs errors — compile/publish/persona map raw os error 2 →
  file not found: <path>.
• Anthropic turn errors surface instead of an empty success (a failed Claude
  turn returns the real error, e.g. low-balance).

Internal

• design/model-agnostic.md (the multi-model → local-model → coding-model →
  cluster arc) and docs/SOP-QA-001-autonomous-feedback.md (an ISO-9001 QA
  feedback procedure).