test: expose truncated Forgejo timelines

test/forge-backends.test.sh

@@ -746,6 +746,7 @@ check "no api base refuses" 1 "cannot reach the forge" \
 # .user.login -> .actor.login. Mutation-verified: collapsing add/remove or
 # emitting .user instead of .actor each reds its own case (#4853).
 timeline_stub() {
+  : >"$timeline_calls"
   # shellcheck disable=SC2317 # invoked indirectly, by forge_api
   curl() {
     local hdr="" out="" url=""
@@ -753,14 +754,44 @@ timeline_stub() {
       case "$1" in -D) hdr="$2"; shift ;; -o) out="$2"; shift ;; -H) shift ;; *) url="$1" ;; esac
       shift
     done
-    printf 'HTTP/1.1 200 OK\r\nX-Total-Count: %s\r\n\r\n' "${FAKE_TL_N:-2}" >"$hdr"
+    printf '%s\n' "$url" >>"$timeline_calls"
+    local page=1 page_body="$FAKE_TIMELINE" page_total="${FAKE_TL_N:-2}"
+    case "$url" in *page=*) page="${url##*page=}"; page="${page%%&*}" ;; esac
+    if [ "${#FAKE_TL_PAGES[@]}" -gt 0 ]; then
+      if [ "$page" -le "${#FAKE_TL_PAGES[@]}" ]; then
+        page_body="${FAKE_TL_PAGES[$((page - 1))]}"
+      else
+        page_body='[]'
+      fi
+      page_total="$(jq 'length' <<<"$page_body")"
+    fi
+    {
+      printf 'HTTP/1.1 200 OK\r\n'
+      [ "${FAKE_TL_HEADERS:-yes}" = no ] || printf 'X-Total-Count: %s\r\n' "$page_total"
+      printf '\r\n'
+    } >"$hdr"
     case "$url" in
-      *timeline*) printf '%s' "$FAKE_TIMELINE" >"$out" ;;
+      *timeline*) printf '%s' "$page_body" >"$out" ;;
       *) printf '[]' >"$out" ;;
     esac
     return 0
   }
 }
+timeline_page() {
+  jq -nc --argjson first "$1" --argjson count "$2" '
+    [range($first; $first + $count)
+      | {
+          type: "label",
+          body: "1",
+          user: {login: "setter"},
+          label: {name: "needs-ruling"},
+          created_at: ("event-" + tostring)
+        }]
+  '
+}
+timeline_calls="$TMP/timeline_calls"
+FAKE_TL_PAGES=()
+FAKE_TL_HEADERS=yes
 FAKE_TIMELINE='[
   {"type":"label","body":"1","user":{"login":"setter"},"label":{"name":"needs-ruling"},"created_at":"2026-08-02T14:58:13Z"},
   {"type":"label","body":"","user":{"login":"setter"},"label":{"name":"needs-ruling"},"created_at":"2026-08-02T15:22:22Z"},
@@ -777,6 +808,48 @@ check "forge_timeline drops non-label events" 0 "" \
   test "$(jq '[.[] | select(.event == null or .event == "")] | length' <<<"$tl")" = 0
 check "forge_timeline uses .actor.login, not a bare .user" 0 "" \
   jq -e 'all(.[]; has("actor") and (.user|not))' <<<"$tl" >/dev/null
+
+# Forgejo's timeline endpoint lies consistently: x-total-count echoes the
+# current page size. With 151 events its pages declare 50, 50, 50 and 1, so
+# strict pagination stops successfully after page 1 and drops the newest 101
+# events. Exhaustion is safe only here because timelines are append-only.
+FAKE_TL_PAGES=(
+  "$(timeline_page 1 50)"
+  "$(timeline_page 51 50)"
+  "$(timeline_page 101 50)"
+  "$(timeline_page 151 1)"
+)
+timeline_stub
+tl="$(REPO=o/r forge_timeline 188)"
+check "forge_timeline exhausts all pages despite per-page total headers" 0 "" \
+  test "$(jq 'length' <<<"$tl")" = 151
+check "forge_timeline retains the newest event beyond page one" 0 "" \
+  jq -e 'any(.[]; .created_at == "event-151")' <<<"$tl" >/dev/null
+
+# A collection exactly divisible by the page size needs one final empty read;
+# stopping after the second full page cannot prove exhaustion.
+FAKE_TL_PAGES=("$(timeline_page 1 50)" "$(timeline_page 51 50)")
+timeline_stub
+exhaustive_count="$(REPO=o/r forge_api --paginate-exhaustive 'repos/o/r/issues/188/timeline' --jq 'length')"
+check "exhaustive pagination terminates after an empty page" 0 "" \
+  test "$exhaustive_count" = 100
+check "an exactly-full exhaustive gather reads the empty third page" 0 "" \
+  test "$(wc -l <"$timeline_calls")" = 3
+
+# The exhaustive path's completeness proof is the short page itself; it must
+# never consult the endpoint's missing or dishonest total header.
+FAKE_TL_PAGES=("$(timeline_page 1 50)" "$(timeline_page 51 1)")
+FAKE_TL_HEADERS=no
+timeline_stub
+check "exhaustive pagination needs no x-total-count header" 0 "" \
+  eq 51 forge_api --paginate-exhaustive 'repos/o/r/issues/188/timeline' --jq 'length'
+FAKE_TL_HEADERS=yes
+
+check "strict and exhaustive pagination are mutually exclusive" 1 "mutually exclusive" \
+  forge_api --paginate --paginate-exhaustive 'repos/o/r/issues/188/timeline'
+check "exhaustive pagination refuses a non-GET method" 1 "GET" \
+  forge_api --paginate-exhaustive --method POST 'repos/o/r/issues/188/timeline'
+
 # Unreadable: curl fails. Status must surface through forge_timeline itself
 # (not a later jq), or the ruling ladder invents a verdict on a half-read.
 # shellcheck disable=SC2317