v0.12.8 — start just works against a live endpoint

Why this release

Two pieces of friction, both hit hardest when the harness and the model server are on different machines (a laptop driving a box elsewhere on the network).

localharness start now picks up the model your endpoint is actually serving. A single-model runtime (vLLM / llama.cpp) serves exactly one checkpoint, so a configured name that no longer matches has exactly one sensible meaning — but start used to hard-error, meaning any server-side model swap 404'd every client still pinned to the old name. In attach mode with no --model, start now reconciles against the live endpoint and adopts the sole served model, printing one line naming the substitution. This makes start consistent with init, which has always discovered models from the endpoint.

Guardrails: an explicit --model still fails loud (naming a model is a deliberate act); two or more served models is a real choice and is never guessed at; an unreachable endpoint still surfaces as "unreachable" rather than being masked by a bogus adoption. The reconciliation runs before the capability probe, so a stale name no longer burns three probe retries — and a session can't start in the wrong tool-call mode.

localharness update upgrades an installed copy to the latest PyPI release. It detects how the copy was installed and shells out to that installer (uv tool upgrade, else pip install --upgrade); --check reports without changing anything. A source/editable checkout is detected and refused with a pointer to git pull — pip'ing over a checkout would shadow your working tree with a published wheel.

Also in this release

• Security: memory-recall output now enters the ContentStore with untrusted origin (#140), closing the "known gaps" note shipped with 0.12.7.
• Fixed: context.compaction_threshold_pct is now actually wired into compaction (#147); ReadTool no longer dumps raw binary content into context.
• Added: session-only start --model/-m, start --list-models, model --download for standalone Hugging Face pulls, and a doctor warning when an AMD GPU is paired with a Vulkan-linked llama.cpp binary (#148).

Thanks to @mjdufresne for #144, #147 and #148 — the AMD/Vulkan work was verified on real AMD hardware.

Pre-1.0: interfaces and config schema may still change. Full detail in CHANGELOG.md.