From 9c71a444212f20a4cbdcb0f4bbeccd84bb6c3d10 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?=E7=A8=8B=E6=99=BA=E8=B6=850668000959?=
 <cheng.zhichao@xydigit.com>
Date: Tue, 2 Jun 2026 22:44:53 +0800
Subject: [PATCH 1/2] fix(session): skip main-session alias during history
 promotion

The PromoteAliasHistory method previously promoted the first non-empty alias session into a new canonical session. When a user upgraded, the migrated main session contained old messages that were copied into every new Web UI session because agent:main:main is always the first alias.

Add isMainSessionAlias() to detect and skip the main session alias during promotion. Fixes #2972.
---
 pkg/memory/jsonl.go | 34 ++++++++++++++++++++++++++++++++++
 1 file changed, 34 insertions(+)

diff --git a/pkg/memory/jsonl.go b/pkg/memory/jsonl.go
index a63598f4e..463aec0e0 100644
--- a/pkg/memory/jsonl.go
+++ b/pkg/memory/jsonl.go
@@ -4,6 +4,8 @@ import (
 	"bufio"
 	"bytes"
 	"context"
+	"crypto/sha256"
+	"encoding/hex"
 	"encoding/json"
 	"fmt"
 	"hash/fnv"
@@ -227,6 +229,11 @@ func (s *JSONLStore) UpsertSessionMeta(
 
 // PromoteAliasHistory atomically promotes the first non-empty alias session
 // into the canonical session when the canonical session is still empty.
+//
+// Main-session aliases (e.g. "agent:main:main" or its opaque form) are
+// skipped during promotion.  The main session is a shared global fallback
+// and promoting its history into individual sessions would attach stale
+// messages to every new Web UI session (issue #2972).
 func (s *JSONLStore) PromoteAliasHistory(
 	_ context.Context,
 	sessionKey string,
@@ -240,6 +247,9 @@ func (s *JSONLStore) PromoteAliasHistory(
 
 	aliases = normalizeAliases(sessionKey, aliases)
 	for _, alias := range aliases {
+		if isMainSessionAlias(alias) {
+			continue
+		}
 		unlock := s.lockSessionPair(sessionKey, alias)
 		promoted, err := s.promoteAliasHistoryLocked(sessionKey, alias, scope, aliases)
 		unlock()
@@ -251,6 +261,30 @@ func (s *JSONLStore) PromoteAliasHistory(
 	return false, nil
 }
 
+// isMainSessionAlias reports whether alias is the legacy or opaque main-session
+// key.  The main session ("agent:<agent>:main") is a shared fallback and should
+// not have its history promoted into individual per-channel sessions.
+func isMainSessionAlias(alias string) bool {
+	if alias == "" {
+		return false
+	}
+	// Legacy form: "agent:main:main" (case-insensitive)
+	if strings.HasPrefix(alias, "agent:") && strings.HasSuffix(alias, ":main") {
+		return true
+	}
+	// Opaque form: "sk_v1_" + SHA256("agent:main:main")
+	if strings.HasPrefix(alias, "sk_v1_") {
+		for _, agentID := range []string{"main", "Main", "MAIN"} {
+			legacy := "agent:" + agentID + ":main"
+			hash := sha256.Sum256([]byte(legacy))
+			if "sk_v1_"+hex.EncodeToString(hash[:]) == alias {
+				return true
+			}
+		}
+	}
+	return false
+}
+
 // ResolveSessionKey returns the canonical session key for a candidate key.
 // It short-circuits direct canonical keys when possible, then scans metadata
 // once to resolve aliases or canonical metadata keys.

From 04664ab514a4b0db26be5860bed388b1c9a8e495 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?=E7=A8=8B=E6=99=BA=E8=B6=850668000959?=
 <cheng.zhichao@xydigit.com>
Date: Wed, 3 Jun 2026 16:46:32 +0800
Subject: [PATCH 2/2] fix(session): tighten main-session alias detection to
 exact 3-part format

Only match agent:X:main, not agent:X:direct:main or agent:X:slack:channel:main. Review feedback from afjcjsbx.
---
 pkg/memory/jsonl.go | 8 ++++++--
 1 file changed, 6 insertions(+), 2 deletions(-)

diff --git a/pkg/memory/jsonl.go b/pkg/memory/jsonl.go
index 463aec0e0..3b2f9ff3f 100644
--- a/pkg/memory/jsonl.go
+++ b/pkg/memory/jsonl.go
@@ -268,9 +268,13 @@ func isMainSessionAlias(alias string) bool {
 	if alias == "" {
 		return false
 	}
-	// Legacy form: "agent:main:main" (case-insensitive)
+	// Legacy form: "agent:main:main" (exactly 3 colon-separated parts)
+	// Must not match "agent:sales:direct:main" etc.
 	if strings.HasPrefix(alias, "agent:") && strings.HasSuffix(alias, ":main") {
-		return true
+		parts := strings.SplitN(alias, ":", 4)
+		if len(parts) == 3 {
+			return true
+		}
 	}
 	// Opaque form: "sk_v1_" + SHA256("agent:main:main")
 	if strings.HasPrefix(alias, "sk_v1_") {