From f560949e545bfc2a79dac5c67c46282b14499d4d Mon Sep 17 00:00:00 2001
From: Elron Bandel <elron.bandel@ibm.com>
Date: Mon, 29 Jun 2026 13:27:44 +0300
Subject: [PATCH] =?UTF-8?q?feat(release):=20affected-set=20=E2=80=94=20bui?=
 =?UTF-8?q?ld=20only=20what=20changed=20since=20the=20last=20release?=
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On a manual dispatch, enumerate diffs HEAD against the previous vX.Y.Z tag and
keeps only the combos + per-task images whose benchmark or agent source changed.
A change under containers/core, gateways, or the root bake is a shared/base
change, so the full fleet rebuilds (the cascade = bulk on base update).
rebuild_bases / --only / tag-release / no-prior-tag all build the full fleet.

Leaves stay full: they're ~38s cache hits, and an empty leaf matrix would skip
the merge job the combos depend on. Plain git-diff is the standard affected-set
(Nx/Turborepo's 'affected') — no content-hash tags, no per-job skip, no script.

Signed-off-by: Elron Bandel <elron.bandel@ibm.com>
---
 .github/workflows/release-images.yml | 19 +++++++++++++++++++
 1 file changed, 19 insertions(+)

diff --git a/.github/workflows/release-images.yml b/.github/workflows/release-images.yml
index 5b262170..1f4b6568 100644
--- a/.github/workflows/release-images.yml
+++ b/.github/workflows/release-images.yml
@@ -268,6 +268,25 @@ jobs:
             combos=$(printf '%s\n%s' "$shared" "$ptc" | jq -cs 'add')
           fi
 
+          # ── affected-set (manual dispatch): build only the combos + per-task whose
+          # benchmark or agent changed since the last release. A change under
+          # containers/core, gateways, or the root bake is a shared/base change → keep
+          # everything (the cascade = "bulk on base update"). rebuild_bases / --only /
+          # tag-release / no-prior-tag all skip this and build the full fleet. Leaves
+          # stay full: they're ~38s cache hits, and an empty leaf matrix would skip the
+          # merge job the combos depend on.
+          LAST=$(git tag --list 'v*' --sort=-v:refname | grep -vxF "${TAG:-}" | head -1 || true)
+          if [ "$IS_DISPATCH" = "true" ] && [ -z "${ONLY:-}" ] && [ "${{ inputs.rebuild_bases }}" != "true" ] && [ -n "$LAST" ]; then
+            ch=$(git diff --name-only "$LAST" HEAD 2>/dev/null || true)
+            if [ -n "$ch" ] && ! printf '%s\n' "$ch" | grep -qE '^containers/(core|gateways)/|^containers/docker-bake\.hcl|^\.github/workflows/release-images'; then
+              names() { printf '%s\n' "$ch" | sed -nE "s#^containers/$1/([^/]+)/.*#\\1#p" | sort -u | jq -Rsc 'split("\n")-[""]'; }
+              cb=$(names benchmarks); ca=$(names agents)
+              combos=$(printf '%s'  "$combos"  | jq -c --argjson b "$cb" --argjson a "$ca" 'map(select((.b|IN($b[])) or (.a|IN($a[]))))')
+              pertask=$(printf '%s' "$pertask" | jq -c --argjson b "$cb" 'map(select(.b|IN($b[])))')
+              echo "affected-set since $LAST: combos=$(jq length <<<"$combos") pertask=$(jq length <<<"$pertask")  (changed benchmarks=$cb agents=$ca)"
+            fi
+          fi
+
           # ── shard oversize lists into ≤256 chunks: [{idx,items}] ──
           # GitHub caps a matrix at 256 jobs; each shard job loops its items. Chunk
           # combos by 25 (thin overlays) and per-task bases by 10 (heavier builds).