docs(changelog): v1.6.1 — pi 0.80.6→0.81.1 (skips 0.81.0)

v1.6.0 was tagged 2026-07-17 but never reached Docker Hub (variant
publish blocked by a site-network SYN-drop fault, since fixed). Cut
v1.6.1 to land v1.6.0's content (agent-browser + pi-devbox-version)
alongside a first pi bump since v1.5.0.

0.81.0 is skipped deliberately: it removed the default stream fallback
for extensions using the pre-0.81 pi-agent-core API, which
pi-observational-memory relies on via agentLoop + stream.result().
0.81.1 restored the fallback (earendil-works/pi#6915), so 0.81.1 — but
not 0.81.0 — is a safe drop-in. pi-fork only imports types; unaffected.

Audit of 0.80.7–0.81.1 vs the two baked extensions and the base image:
no breaking changes affect pi-devbox. Node engine bumped to >=22.19.0
in 0.81.0 (nodesource 22.x currently 22.23.1, so no engine bump needed).

Base-affecting via the npm install line, so base-<hash> rebuilds.

CHANGELOG.md

@@ -15,8 +15,54 @@ Pre-v1.0.0 tags followed the pi npm version (`v{pi_version}[letter]`).
 
 _Nothing yet — next release's changes will accrue here._
 
+## v1.6.1 — 2026-07-22
+
+Patch release. Headline: **pi `0.80.6` → `0.81.1`** (npm `latest`) — the first
+pi bump since v1.5.0.
+
+> **Note on v1.6.0.** The `v1.6.0` git tag was cut on 2026-07-17 (agent-browser +
+> `pi-devbox-version`, see below) but never reached Docker Hub: the variant
+> publish was blocked by an intermittent SYN-drop fault on the on-prem CI
+> network (`ci-network-diagnosis.md`, since resolved). v1.6.1 lands v1.6.0's
+> content **plus** the pi bump in one release; there is no `v1.6.0` image on
+> Docker Hub. The `v1.6.0` git tag is left in place as an accurate record of
+> what was intended on that day.
+
+### Changed
+
+- **pi `0.80.6` → `0.81.1`.** The CI resolves `pi@latest` at build time; latest
+  is now `0.81.1`. The intermediate `0.81.0` is deliberately skipped: 0.81.0
+  removed the default stream fallback for extensions using the pre-0.81
+  `@earendil-works/pi-agent-core` API, which `pi-observational-memory` relies
+  on (`agentLoop` + `stream.result()` in the observer/reflector/dropper
+  agents). 0.81.1 restored the fallback ([earendil-works/pi#6915][pi-6915]),
+  making 0.81.1 — but not 0.81.0 — a safe drop-in. `pi-fork` only imports
+  types from `pi-agent-core` and is unaffected. Everything since v1.5.0's
+  baked `0.80.6` (i.e. `0.80.7`–`0.80.10`, `0.81.0`, `0.81.1`) was audited for
+  breaking changes against the two baked extensions — none affect this image.
+  The Node engine requirement rose to `>=22.19.0` in `0.81.0`; the base still
+  ships `22.23.1` (nodesource 22.x), so no engine bump is needed. Highlights
+  users inherit from the upstream jump: **local llama.cpp router support**
+  (search + download Hugging Face models, explicit load/unload, live
+  progress); **full pi-ai provider extensions** (extensions can now register
+  complete providers with native auth, model refresh, filtering, and
+  streaming); **Qwen Token Plan** subscription providers; **resilient
+  compaction / branch-summary retries** on transient provider failures with
+  lifecycle events exposed to interactive, JSON, RPC, and SDK consumers;
+  expanded usage accounting for tools, compaction, and branch summaries.
+  Base-affecting (npm install line rebuilds), so `base-<hash>` rebuilds. See
+  the [pi changelog][pi-changelog] for the full list.
+
+[pi-6915]: https://github.com/earendil-works/pi/issues/6915
+[pi-changelog]: https://github.com/earendil-works/pi/blob/main/CHANGELOG.md
+
 ## v1.6.0 — 2026-07-13
 
+> ⚠️ **Never published to Docker Hub.** Tagged in git on 2026-07-17 but the
+> variant publish was blocked by a site-network fault before the image reached
+> the registry. Superseded by v1.6.1, which carries this release's content
+> forward alongside the `pi 0.81.1` bump.
+
 ### Added
 
 - **`agent-browser` — headless browser automation, baked into every variant.**