From 2bc1cf3417f9c0ab447126763f04c7a69c19246e Mon Sep 17 00:00:00 2001
From: fiatjaf <fiatjaf@gmail.com>
Date: Thu, 2 Apr 2026 03:46:54 -0300
Subject: [PATCH] performReq now uses "read" relays from p/P-tags when no
 authors are specified in outbox mode.

---
 req.go | 144 ++++++++++++++++++++++++++++++++++++++++-----------------
 1 file changed, 102 insertions(+), 42 deletions(-)

diff --git a/req.go b/req.go
index bbd450a..502bbba 100644
--- a/req.go
+++ b/req.go
@@ -291,6 +291,24 @@ func performReq(
 	} else if outbox {
 		defs := make([]nostr.DirectedFilter, 0, len(filter.Authors)*2)
 
+		pTagPubkeys := make([]nostr.PubKey, 0, 4)
+		if len(filter.Authors) == 0 && filter.Tags != nil {
+			seen := make(map[nostr.PubKey]struct{})
+			pTags := append([]string{}, filter.Tags["p"]...)
+			pTags = append(pTags, filter.Tags["P"]...)
+			for _, value := range pTags {
+				pubkey, err := parsePubKey(value)
+				if err != nil {
+					continue
+				}
+				if _, ok := seen[pubkey]; ok {
+					continue
+				}
+				seen[pubkey] = struct{}{}
+				pTagPubkeys = append(pTagPubkeys, pubkey)
+			}
+		}
+
 		for _, relayUrl := range relayUrls {
 			defs = append(defs, nostr.DirectedFilter{
 				Filter: filter,
@@ -298,54 +316,96 @@ func performReq(
 			})
 		}
 
-		// relays for each pubkey
-		errg := errgroup.Group{}
-		errg.SetLimit(16)
-		mu := sync.Mutex{}
-		logverbose("gathering outbox relays for %d authors...\n", len(filter.Authors))
-		for _, pubkey := range filter.Authors {
-			errg.Go(func() error {
-				n := int(outboxRelaysPerPubKey)
-				for _, url := range sys.FetchOutboxRelays(ctx, pubkey, n) {
-					if slices.Contains(relayUrls, url) {
-						// already specified globally, ignore
-						continue
-					}
-					if !nostr.IsValidRelayURL(url) {
-						continue
-					}
-
-					matchUrl := func(def nostr.DirectedFilter) bool { return def.Relay == url }
-					idx := slices.IndexFunc(defs, matchUrl)
-					if idx == -1 {
-						// new relay, add it
-						mu.Lock()
-						// check again after locking to prevent races
-						idx = slices.IndexFunc(defs, matchUrl)
-						if idx == -1 {
-							// then add it
-							filter := filter.Clone()
-							filter.Authors = []nostr.PubKey{pubkey}
-							defs = append(defs, nostr.DirectedFilter{
-								Filter: filter,
-								Relay:  url,
-							})
-							mu.Unlock()
-							continue // done with this relay url
+		if len(filter.Authors) == 0 && len(pTagPubkeys) > 0 {
+			// relays for p tags when no authors are given
+			errg := errgroup.Group{}
+			errg.SetLimit(16)
+			mu := sync.Mutex{}
+			logverbose("gathering inbox relays for %d p-tags...\n", len(pTagPubkeys))
+			for _, pubkey := range pTagPubkeys {
+				errg.Go(func() error {
+					n := int(outboxRelaysPerPubKey)
+					for _, url := range sys.FetchInboxRelays(ctx, pubkey, n) {
+						if slices.Contains(relayUrls, url) {
+							// already specified globally, ignore
+							continue
+						}
+						if !nostr.IsValidRelayURL(url) {
+							continue
 						}
 
-						// otherwise we'll just use the idx
-						mu.Unlock()
+						matchUrl := func(def nostr.DirectedFilter) bool { return def.Relay == url }
+						idx := slices.IndexFunc(defs, matchUrl)
+						if idx == -1 {
+							// new relay, add it
+							mu.Lock()
+							idx = slices.IndexFunc(defs, matchUrl)
+							if idx == -1 {
+								defs = append(defs, nostr.DirectedFilter{
+									Filter: filter,
+									Relay:  url,
+								})
+								mu.Unlock()
+								continue
+							}
+							mu.Unlock()
+						}
 					}
 
-					// existing relay, add this pubkey
-					defs[idx].Authors = append(defs[idx].Authors, pubkey)
-				}
+					return nil
+				})
+			}
+			errg.Wait()
+		} else {
+			// relays for each pubkey
+			errg := errgroup.Group{}
+			errg.SetLimit(16)
+			mu := sync.Mutex{}
+			logverbose("gathering outbox relays for %d authors...\n", len(filter.Authors))
+			for _, pubkey := range filter.Authors {
+				errg.Go(func() error {
+					n := int(outboxRelaysPerPubKey)
+					for _, url := range sys.FetchOutboxRelays(ctx, pubkey, n) {
+						if slices.Contains(relayUrls, url) {
+							// already specified globally, ignore
+							continue
+						}
+						if !nostr.IsValidRelayURL(url) {
+							continue
+						}
 
-				return nil
-			})
+						matchUrl := func(def nostr.DirectedFilter) bool { return def.Relay == url }
+						idx := slices.IndexFunc(defs, matchUrl)
+						if idx == -1 {
+							// new relay, add it
+							mu.Lock()
+							// check again after locking to prevent races
+							idx = slices.IndexFunc(defs, matchUrl)
+							if idx == -1 {
+								// then add it
+								filter := filter.Clone()
+								filter.Authors = []nostr.PubKey{pubkey}
+								defs = append(defs, nostr.DirectedFilter{
+									Filter: filter,
+									Relay:  url,
+								})
+								mu.Unlock()
+								continue // done with this relay url
+							}
+
+							// otherwise we'll just use the idx
+							mu.Unlock()
+						}
+
+						// existing relay, add this pubkey
+						defs[idx].Authors = append(defs[idx].Authors, pubkey)
+					}
+
+					return nil
+				})
+			}
+			errg.Wait()
 		}
-		errg.Wait()
 
 		if stream {
 			logverbose("running subscription with %d directed filters...\n", len(defs))