fix(framework): validate milestone title before provider reads (#1841)

Refuse missing or empty creation titles before provider detection while preserving title-free listing. Prove zero-provider usage failures and unchanged synthetic list and creation payload behavior.

Co-Authored-By: GPT-6.1-Sol (Codex) <[email protected]>

packages/mosaic/framework/tools/git/milestone-create.sh

@@ -80,6 +80,12 @@ while [[ $# -gt 0 ]]; do
     esac
 done
 
+# Creation usage errors must stop before provider detection or credentials.
+# Listing does not require a title.
+if [[ "$LIST_ONLY" != true && -z "$TITLE" ]]; then
+    usage_error "Title is required (-t) for creating milestones"
+fi
+
 PLATFORM=$(detect_platform)
 
 if [[ "$LIST_ONLY" == true ]]; then
@@ -106,10 +112,6 @@ if [[ "$LIST_ONLY" == true ]]; then
     exit 0
 fi
 
-if [[ -z "$TITLE" ]]; then
-    usage_error "Title is required (-t) for creating milestones"
-fi
-
 case "$PLATFORM" in
     github)
         # GitHub uses the API for milestone creation

packages/mosaic/framework/tools/git/test-milestone-create-usage-contract.sh

@@ -90,6 +90,7 @@ expect_stderr "[Uu]nknown option" "unknown option names itself on stderr"
 
 # 3. Missing required PR number: rc 2, stderr.
 expect_rc 2 "missing -t exits 2"
+expect_rc 2 "empty title exits 2" -t ""
 expect_stderr "Title is required" "missing -t message on stderr"
 
 
@@ -129,4 +130,42 @@ done
 # the arm above proves only parse acceptance and non-usage classification.
 # Parser-failure arms (1-4) remain zero-contact (asserted at 4b).
 
+# Positive provider paths remain real wrapper dispatch with fixture-only gh.
+# --list remains legal without a title; ordinary creation retains its JSON body.
+GH_REPO="$WORK_DIR/github-fixture"
+mkdir -p "$GH_REPO"
+git -C "$GH_REPO" init -q
+git -C "$GH_REPO" remote add origin https://github.com/fixture/widgets.git
+: > "$PROBE_LOG"
+PAYLOAD_LOG="$WORK_DIR/payload.json"
+export PAYLOAD_LOG
+cat > "$BIN_DIR/gh" <<STUB
+#!/usr/bin/env bash
+echo "gh \$*" >> "$PROBE_LOG"
+if [[ "\$*" == "api repos/:owner/:repo/milestones --jq "* ]]; then
+    printf '7\tfixture-list\topen\t0/0\n'
+    exit 0
+fi
+if [[ "\$*" == "api repos/:owner/:repo/milestones --method POST --input -" ]]; then
+    cat > "\$PAYLOAD_LOG"
+    printf '{"id":8}\n'
+    exit 0
+fi
+exit 99
+STUB
+chmod +x "$BIN_DIR/gh"
+(
+    cd "$GH_REPO"
+    PATH="$BIN_DIR:$PATH" "$SCRIPT_DIR/milestone-create.sh" --list
+) > "$OUT_FILE" 2> "$ERR_FILE" || fail "list without title failed"
+grep -q 'fixture-list' "$OUT_FILE" || fail "list result missing"
+(
+    cd "$GH_REPO"
+    PATH="$BIN_DIR:$PATH" "$SCRIPT_DIR/milestone-create.sh" -t 'fixture "title"' -d description --due 2030-01-02
+) > "$OUT_FILE" 2> "$ERR_FILE" || fail "valid creation failed"
+grep -q 'created successfully' "$OUT_FILE" || fail "creation success missing"
+jq -e '.title == "fixture \"title\"" and .description == "description" and .due_on == "2030-01-02T00:00:00Z"' "$PAYLOAD_LOG" >/dev/null || fail "creation payload changed"
+[[ "$(wc -l < "$PROBE_LOG")" -eq 2 ]] || fail "unexpected positive-path provider contact"
+[[ "$(grep -c '^gh api .* --method POST --input -$' "$PROBE_LOG")" -eq 1 ]] || fail "creation did not invoke expected provider method"
+
 echo "milestone-create.sh usage-contract regression passed (R1/R4)"