v4 is not a version bump

[askalf]

Every dario release so far has answered one question:

Can you point every tool at one local URL and route it anywhere?

v1 → v3 is the answer. It works. 19 point releases of hardening — template replay, OAuth single-flight, SSE reassembly, sealed-sender pooling, SLSA-attested every tag. The router is shipped.

That was the prerequisite.

v4 is what the prerequisite was for.

The endpoint stays where it is. What's behind it changes shape.

No dates. No specifics. If you want the first look, watch this space — the reveal lands here.

— askalf

[askalf]

Update — 2026-05-16, hours after v4.0.0 shipped:

v4.1.0 and v4.2.0 followed on the same day:

• v4.1.0 — overage-guard. dario now halts itself the moment any upstream response carries representative-claim: overage and returns 503 with an Anthropic-shaped error body until you run dario resume or the cooldown clears. Subscribers should never see a single overage hit during normal operation; one means something is wrong, and continuing to forward requests bleeds against per-token billing. The TUI's Status / Hits / Analytics tabs all surface the halt state in real time. See #288 for the spec + test/overage-guard-e2e-live.mjs for the verified end-to-end halt cycle (20/20 assertions, mocked upstream, halt → 503 → resume → flow).

• v4.2.0 — dario shim deprecated (removal scheduled for v5.x). Side-by-side fingerprint diff against the proxy's full-shape rebuild showed shim only normalizes 3 of the 8 axes Anthropic's billing classifier inspects (system blocks, agent identity, header order). On the 1-block-system shape that claude -p and Agent-SDK emit, shim returns null and the request goes upstream unchanged — total passthrough, no fingerprint replay. For interactive CC the gap is a no-op because CC's own outbound matches every axis; for non-CC clients shim was always under-protected. See CHANGELOG v4.2.0 for the 8-axis comparison table.

Five releases in one calendar day:

	When	What
v4.0.0	11:45Z	TUI as default surface
v4.0.1	13:10Z	CC v2.1.143 drift patch + template re-bake
v4.1.0	15:13Z	overage-guard
v4.1.1	15:35Z	polish batch (resume regex, help text, README, enum validation)
v4.2.0	19:56Z	shim deprecation

All on npm @askalf/dario@latest, all SLSA-attested, all multi-arch on ghcr.io/askalf/dario:v4 and :latest.