Loaded up for the 3rd redo

Still on potion-voice

worker-toolkit-potion-polyglot/scripts/lib/resolve-pin.sh

@@ -0,0 +1,96 @@
+# shellcheck shell=bash
+#
+# resolve_pin — turn a task's pinned commit into a SHA that exists in the repo,
+# translating through a commit map when history has been rewritten under it.
+#
+# A task pins a commit in task.toml. If that repo's history is later rewritten
+# (to strip something that should never have shipped, say), every rewritten
+# commit gets a new SHA and the pin stops resolving — including on machines we
+# cannot reach, holding tasks we cannot edit. A commit map lets those pins keep
+# working: `<old-sha> <new-sha>` per line, at task-shared/commit-maps/<member>.map,
+# <member> being the task's `repo` key — a standalone toolkit checks its repo out
+# at repo/, so the directory name is not the member name and cannot be the key.
+#
+# The map is only consulted when the pin does not resolve, so it carries only
+# rewritten commits — an unchanged commit resolves on its own and its identity
+# row could never be read.
+#
+# Usage (source, then call):
+#   . "$(dirname "$0")/lib/resolve-pin.sh"
+#   sha=$(resolve_pin "$REPO_DIR" "$COMMIT" "$TOOLKIT_ROOT/task-shared/commit-maps" "$MEMBER") || exit 1
+#
+# Writes the resolved SHA to stdout, notes on stderr. Returns non-zero if the
+# pin cannot be resolved, having explained why.
+
+RESOLVE_PIN_MAX_HOPS="${RESOLVE_PIN_MAX_HOPS:-25}"
+_RESOLVE_PIN_ZERO='0000000000000000000000000000000000000000'
+
+# Look one hop: echo the successor of $1 in map $2, or nothing. Fails if the
+# prefix is ambiguous, which would otherwise pick an arbitrary commit.
+_resolve_pin_hop() {
+    local from="$1" map="$2" hits
+    hits=$(awk -v p="$from" '
+        /^#/ || NF < 2 { next }
+        index($1, p) == 1 { print $2 }
+    ' "$map" | sort -u)
+    [ -z "$hits" ] && return 1
+    if [ "$(printf '%s\n' "$hits" | wc -l | tr -d ' ')" -gt 1 ]; then
+        echo "  pin $from is ambiguous in $(basename "$map") — use a longer SHA" >&2
+        return 2
+    fi
+    printf '%s\n' "$hits"
+}
+
+resolve_pin() {
+    local repo_dir="$1" commit="$2" map_dir="${3:-}" key="${4:-}" sha map cur hops next rc
+
+    # Present in the repo: nothing to translate.
+    if sha=$(git -C "$repo_dir" rev-parse --quiet --verify "$commit^{commit}" 2>/dev/null); then
+        printf '%s\n' "$sha"
+        return 0
+    fi
+
+    map=""
+    if [ -n "$map_dir" ]; then
+        if [ -n "$key" ] && [ -f "$map_dir/$key.map" ]; then
+            map="$map_dir/$key.map"
+        elif [ -f "$map_dir/$(basename "$repo_dir").map" ]; then
+            map="$map_dir/$(basename "$repo_dir").map"
+        fi
+    fi
+    if [ -z "$map" ]; then
+        echo "Error: pinned commit $commit is not in $repo_dir, and no commit map is available." >&2
+        echo "       The repo may be a shallow or partial copy — try a full clone." >&2
+        return 1
+    fi
+
+    # Follow the chain: a commit rewritten more than once maps forward a hop per
+    # rewrite, so keep going until the SHA exists or the trail ends.
+    cur="$commit"
+    hops=0
+    while [ "$hops" -lt "$RESOLVE_PIN_MAX_HOPS" ]; do
+        next=$(_resolve_pin_hop "$cur" "$map"); rc=$?
+        [ "$rc" -eq 2 ] && return 1
+        if [ "$rc" -ne 0 ]; then
+            echo "Error: pinned commit $commit is not in $repo_dir and is not in $(basename "$map")." >&2
+            echo "       It predates the map, or came from a repo copy this toolkit was not built from." >&2
+            return 1
+        fi
+        if [ "$next" = "$_RESOLVE_PIN_ZERO" ]; then
+            echo "Error: pinned commit $commit was deleted by a history rewrite, not rewritten." >&2
+            echo "       Re-pin this task to a commit that still exists." >&2
+            return 1
+        fi
+        if sha=$(git -C "$repo_dir" rev-parse --quiet --verify "$next^{commit}" 2>/dev/null); then
+            echo "  Pin $commit was rewritten; using $sha" >&2
+            printf '%s\n' "$sha"
+            return 0
+        fi
+        cur="$next"
+        hops=$((hops + 1))
+    done
+
+    echo "Error: pinned commit $commit did not settle after $RESOLVE_PIN_MAX_HOPS hops." >&2
+    echo "       $(basename "$map") may contain a cycle." >&2
+    return 1
+}