Add apt-get upgrade to core packages layer

Pair 'apt-get upgrade -y --no-install-recommends' with the existing
update + install in the first RUN step. Picks up security/CVE fixes
that land in the Debian repos between base-image rebuilds. Same layer
as the install to avoid bloating history; combined with apt-get clean
and rm -rf /var/lib/apt/lists/* at the end so no index cache is kept.

Today this is a no-op (debian:trixie-slim is current: 0 upgraded).
Future-proofs against the lag between a CVE fix being published and
the next base-image rebuild.

CHANGELOG.md

@@ -19,6 +19,7 @@ Tags follow `v{opencode_version}[letter]` — bare tag for the first build on a
   - `curl --retry 5 --retry-delay 5 --retry-all-errors` on both the `-fsSL` GET requests and the `-sI` HEAD requests used for `/releases/latest` redirect resolution. 5 attempts with 5 s back-off eats most transient CDN hiccups without failing the build.
   - Added `[ -n "$V" ]` assertion after each version-resolution step. If the HEAD redirect ever fails to produce a tag name, the build fails fast with an empty-version message rather than trying to download `.../v//...` and producing a confusing 404.
   - Same hardening applied to the optional Go install block (go.dev JSON feed + tarball download) and the nodesource apt-repo setup script.
+- **Security:** Added `apt-get upgrade -y` to the core-packages RUN step. Picks up any security/CVE fixes published between `debian:trixie-slim` base-image rebuilds. Paired with the existing `update` and `install` in the same layer so image history isn't bloated. Today this produced `0 upgraded` (base image is current), but it future-proofs against the next CVE drop.
 
 ## v1.14.29 — 2026-04-28
 

Dockerfile

@@ -15,7 +15,12 @@ LABEL org.opencontainers.image.source="https://gitea.jordbo.se/joakimp/opencode-
 ENV DEBIAN_FRONTEND=noninteractive
 
 # ── Core system packages ─────────────────────────────────────────────
-RUN apt-get update && apt-get install -y --no-install-recommends \
+# apt-get upgrade picks up any security/CVE fixes published between
+# debian:trixie-slim base-image rebuilds. Paired with the index update
+# and the install in the same layer so we don't bloat image history.
+RUN apt-get update && \
+    apt-get upgrade -y --no-install-recommends && \
+    apt-get install -y --no-install-recommends \
     ca-certificates \
     curl \
     wget \
@@ -45,6 +50,7 @@ RUN apt-get update && apt-get install -y --no-install-recommends \
     python3-pip \
     python3-venv \
     && ln -s /usr/bin/fdfind /usr/local/bin/fd \
+    && apt-get clean \
     && rm -rf /var/lib/apt/lists/*
 
 # ── Go-compiled tools (install from GitHub to avoid CVEs in Debian's old Go builds)