From 1c181c1739739d93ddc2f3b9aae8a878ce972e38 Mon Sep 17 00:00:00 2001
From: Postil Maintainer <morgaesis+git@morgaes.is>
Date: Sat, 13 Jun 2026 03:44:55 +0000
Subject: [PATCH] Add x86_64 musl prebuilt target; installer accepts musl

Add x86_64-unknown-linux-musl to the release build matrix so Alpine and
other musl-libc systems get a prebuilt, statically linked binary. The
musl leg runs on an ubuntu runner with musl-tools installed for the
musl-gcc linker wrapper; packaging, checksum, and cosign keyless signing
are identical to the existing targets, producing
postil-x86_64-unknown-linux-musl.tar.gz with .sha256, .sig, and .pem.

install.sh now detects musl (via ldd --version or the /lib/ld-musl-*
loader) and maps to the musl asset instead of refusing the install. The
glibc path and the checksum/signature verification flow are unchanged.
---
 .github/workflows/release.yml |  7 +++++++
 ROADMAP.md                    |  5 ++---
 install.sh                    | 10 +++++++---
 3 files changed, 16 insertions(+), 6 deletions(-)

diff --git a/.github/workflows/release.yml b/.github/workflows/release.yml
index 42db430..44ee534 100644
--- a/.github/workflows/release.yml
+++ b/.github/workflows/release.yml
@@ -11,6 +11,10 @@ jobs:
         include:
           - target: x86_64-unknown-linux-gnu
             os: ubuntu-latest
+          - target: x86_64-unknown-linux-musl
+            os: ubuntu-latest
+            # musl needs the musl-gcc wrapper/linker from musl-tools (Alpine static build).
+            musl: true
           - target: aarch64-unknown-linux-gnu
             os: ubuntu-24.04-arm
           - target: x86_64-apple-darwin
@@ -30,6 +34,9 @@ jobs:
       - uses: dtolnay/rust-toolchain@stable
         with:
           targets: ${{ matrix.target }}
+      - name: Install musl toolchain
+        if: matrix.musl
+        run: sudo apt-get update && sudo apt-get install -y musl-tools
       - uses: Swatinem/rust-cache@v2
       - run: cargo test --quiet
       # SHA-pinned: this action handles the OIDC token.
diff --git a/ROADMAP.md b/ROADMAP.md
index 0b52962..63f51c1 100644
--- a/ROADMAP.md
+++ b/ROADMAP.md
@@ -17,7 +17,8 @@
 - Model cascade + concurrent multi-model consensus over any OpenAI-compatible endpoint;
   bounded retry with backoff on transient provider errors.
 - Verified `curl | sh` install script with SHA-256 checksum verification; prebuilt
-  release binaries for four targets.
+  release binaries for five targets, including x86_64 musl (Alpine) for static-libc
+  systems.
 - Sigstore keyless signing of release artifacts (cosign, GitHub OIDC); the installer
   verifies the signature when cosign is present and refuses a stripped signature
   unless explicitly overridden.
@@ -36,8 +37,6 @@
 - `postil respond` parity on GitLab/Bitbucket/Azure (today it is GitHub-only), and a
   visible error reply when the hosted bot exhausts its retries (today a dead respond
   job is only logged).
-- musl (Alpine) prebuilt target; the installer currently refuses musl and points at
-  the source build.
 - An `/evidence` benchmark: Postil's own silence rate and confirmed-finding rate on
   public OSS PRs, with raw envelopes.
 
diff --git a/install.sh b/install.sh
index 9e40f46..9c8c4dd 100755
--- a/install.sh
+++ b/install.sh
@@ -47,9 +47,13 @@ case "$arch" in
     aarch64|arm64) arch_part="aarch64" ;;
     *) err "unsupported architecture: $arch ($FROM_SOURCE)" ;;
 esac
-# The prebuilt Linux binaries link glibc; a musl libc (Alpine) cannot run them.
-if [ "$os" = "Linux" ] && ldd --version 2>&1 | grep -qi musl; then
-    err "musl libc detected (Alpine?); no musl prebuilt yet ($FROM_SOURCE)"
+# glibc and musl binaries are not interchangeable, so pick the matching libc on
+# Linux. Alpine and other musl systems report "musl" in `ldd --version`; the
+# presence of the musl loader (/lib/ld-musl-*) is a fallback when ldd is absent.
+if [ "$os" = "Linux" ]; then
+    if { ldd --version 2>&1 | grep -qi musl; } || ls /lib/ld-musl-* >/dev/null 2>&1; then
+        os_part="unknown-linux-musl"
+    fi
 fi
 target="${arch_part}-${os_part}"