fix(googlereader): raise item IDs limit to 10000

Since fbbff63f, a non-positive limit is clamped to model.MaxEntryLimit
instead of producing an unbounded query. /stream/items/ids defaults "n"
to 0, so omitting it started returning at most 1000 IDs, whereas
previous versions returned every matching entry.

Cap the four ID stream handlers at model.MaxEntryIDsLimit instead, like
the REST API does for /v1/entries/ids: ID lists are cheap, and clients
can still follow the continuation offset for the remainder.

Fixes: #4479

internal/googlereader/README.md

@@ -417,7 +417,7 @@ Required query parameters:
 
 Optional query parameters:
 
-- `n`: maximum number of items to return
+- `n`: maximum number of items to return, capped at 10000
 - `c`: numeric offset continuation token
 - `r`: sort direction, `o` for ascending, anything else for descending
 - `ot`: only items published after this Unix timestamp in seconds
@@ -437,7 +437,8 @@ Notes:
 - exactly one `s` value is expected
 - label streams are not supported here
 - when `xt` contains the `read` stream, `reading-list` and `feed/<id>` behave as unread-only queries
-- if `n` is omitted, the query is effectively unbounded
+- if `n` is omitted, or is above 10000 or non-positive, 10000 items are returned at most
+- clients must follow `continuation` to retrieve the remaining items
 - `continuation` is a numeric offset encoded as a JSON string, not an opaque token
 
 Response shape:

internal/googlereader/handler.go

@@ -1012,7 +1012,7 @@ func (h *greaderHandler) handleReadingListStreamHandler(w http.ResponseWriter, r
 	)
 
 	builder := h.store.NewEntryQueryBuilder(rm.UserID).
-		WithLimit(rm.Count).
+		WithLimitAndMaximum(rm.Count, model.MaxEntryIDsLimit).
 		WithOffset(rm.Offset).
 		WithSorting(model.DefaultSortingOrder, rm.SortDirection)
 
@@ -1049,7 +1049,7 @@ func (h *greaderHandler) handleReadingListStreamHandler(w http.ResponseWriter, r
 func (h *greaderHandler) handleStarredStreamHandler(w http.ResponseWriter, r *http.Request, rm requestModifiers) {
 	builder := h.store.NewEntryQueryBuilder(rm.UserID).
 		WithStarred(true).
-		WithLimit(rm.Count).
+		WithLimitAndMaximum(rm.Count, model.MaxEntryIDsLimit).
 		WithOffset(rm.Offset).
 		WithSorting(model.DefaultSortingOrder, rm.SortDirection)
 
@@ -1073,7 +1073,7 @@ func (h *greaderHandler) handleStarredStreamHandler(w http.ResponseWriter, r *ht
 func (h *greaderHandler) handleReadStreamHandler(w http.ResponseWriter, r *http.Request, rm requestModifiers) {
 	builder := h.store.NewEntryQueryBuilder(rm.UserID).
 		WithStatuses(model.EntryStatusRead).
-		WithLimit(rm.Count).
+		WithLimitAndMaximum(rm.Count, model.MaxEntryIDsLimit).
 		WithOffset(rm.Offset).
 		WithSorting(model.DefaultSortingOrder, rm.SortDirection)
 
@@ -1125,7 +1125,7 @@ func (h *greaderHandler) handleFeedStreamHandler(w http.ResponseWriter, r *http.
 
 	builder := h.store.NewEntryQueryBuilder(rm.UserID).
 		WithFeedID(feedID).
-		WithLimit(rm.Count).
+		WithLimitAndMaximum(rm.Count, model.MaxEntryIDsLimit).
 		WithOffset(rm.Offset).
 		WithSorting(model.DefaultSortingOrder, rm.SortDirection)