fix(doc): mention 配对增加双射一致性校验

评审连续三轮卡在「目标互换仍返回 verified=true」。逐目标核验需要
openDingTalkId → staffId 的反查，而该反查在 CLI 面上不存在（openDingTalkId 仅作
输出字段；contact 查询入口是姓名/手机/部门/角色），dws api 又要求自有应用凭证且
把 raw OpenAPI 塞进文档校验路径违背现有架构——故无法在本 PR 内实现。

但按位置配对之外还有两条纯本地可判的约束此前没做，现补上：
- 同一个 openDingTalkId 必须解析到同一个 profile 目标
- 两个不同的 openDingTalkId 不得解析到同一个 profile 目标

这能捕捉服务端把身份搞混（同 id 前后不一致、不同 id 撞到同一人）的情形，把不可
判范围收窄到「两个不同 id 的目标互换」这一项——作者侧从不携带解析后的 staffId，
(A→X,B→Y) 与 (A→Y,B→X) 在本地信息量下不可区分，属信息不足而非实现薄弱。

验证：新增 4 行表驱动用例覆盖两条约束的正反面，另测 destination 提取的边界；
变更行覆盖率 100%；internal/shortcut/... 与 internal/helpers/... 全绿。

internal/shortcut/doc/content_shortcuts.go

@@ -1281,13 +1281,37 @@ func isProfileLinkToken(token string) bool {
 	return strings.HasPrefix(token, docFingerprintLinkTokenPrefix+docProfileLinkPrefix)
 }
 
+// docFingerprintLinkDestination extracts the link destination from a fingerprint
+// token shaped "open\x00link:<destination>\x00<title>".
+func docFingerprintLinkDestination(token string) string {
+	rest := strings.TrimPrefix(token, docFingerprintLinkTokenPrefix)
+	if idx := strings.IndexByte(rest, 0); idx >= 0 {
+		return rest[:idx]
+	}
+	return rest
+}
+
 // markdownMentionAwareTokensEqual compares two fingerprint token sequences,
 // tolerating exactly one kind of difference: an authored mention protocol link
 // may appear as a profile link in the readback.
+//
+// Pairs are additionally required to form a consistent bijection: one
+// openDingTalkId must resolve to one profile target throughout the document, and
+// two different openDingTalkIds must not resolve to the same target. Both checks
+// are decidable locally and catch a service that mixed identities up.
+//
+// What remains undetectable is a permutation of two *distinct* targets: the
+// authored side never carries the resolved staffId, so (A→X, B→Y) and
+// (A→Y, B→X) are indistinguishable here. That is missing information, not a
+// weaker implementation — closing it needs the service to report what it
+// rewrote, or a reverse openDingTalkId lookup that the CLI surface does not
+// expose.
 func markdownMentionAwareTokensEqual(actual, expected []string) bool {
 	if len(actual) != len(expected) {
 		return false
 	}
+	resolved := map[string]string{}
+	claimed := map[string]string{}
 	for index := range expected {
 		if actual[index] == expected[index] {
 			continue
@@ -1295,6 +1319,16 @@ func markdownMentionAwareTokensEqual(actual, expected []string) bool {
 		if !isMentionProtocolLinkToken(expected[index]) || !isProfileLinkToken(actual[index]) {
 			return false
 		}
+		mention := docFingerprintLinkDestination(expected[index])
+		target := docFingerprintLinkDestination(actual[index])
+		if previous, seen := resolved[mention]; seen && previous != target {
+			return false
+		}
+		if previous, seen := claimed[target]; seen && previous != mention {
+			return false
+		}
+		resolved[mention] = target
+		claimed[target] = mention
 	}
 	return true
 }

internal/shortcut/doc/doc_readback_verification_test.go

@@ -853,3 +853,62 @@ func TestCrossPlatformCoverageDocMentionSuffixComparisonLayers(t *testing.T) {
 		t.Fatal("an oversized readback must not be accepted")
 	}
 }
+
+// Mention pairing must form a consistent bijection. Neither check needs an
+// identity lookup, so both are enforced locally; a permutation of two distinct
+// targets stays undetectable because the authored side carries no staffId.
+func TestCrossPlatformCoverageDocMentionPairingRequiresBijection(t *testing.T) {
+	const (
+		mentionA = "alidocs-mcp://doc/mention?openDingTalkId=DEXAMPLEAAAA"
+		mentionB = "alidocs-mcp://doc/mention?openDingTalkId=DEXAMPLEBBBB"
+		profile1 = "dingtalk://dingtalkclient/page/profile?corp_id=dingexamplecorpid&staff_id=100001"
+		profile2 = "dingtalk://dingtalkclient/page/profile?corp_id=dingexamplecorpid&staff_id=100002"
+	)
+
+	for _, tc := range []struct {
+		name     string
+		expected string
+		actual   string
+		want     bool
+	}{
+		{
+			"one id resolving to one target twice is accepted",
+			"[@甲](" + mentionA + ") 与 [@甲](" + mentionA + ")",
+			"[@甲](" + profile1 + ") 与 [@甲](" + profile1 + ")",
+			true,
+		},
+		{
+			"the same id resolving to two different targets is rejected",
+			"[@甲](" + mentionA + ") 与 [@甲](" + mentionA + ")",
+			"[@甲](" + profile1 + ") 与 [@甲](" + profile2 + ")",
+			false,
+		},
+		{
+			"two different ids collapsing onto one target is rejected",
+			"[@甲](" + mentionA + ") 与 [@乙](" + mentionB + ")",
+			"[@甲](" + profile1 + ") 与 [@乙](" + profile1 + ")",
+			false,
+		},
+		{
+			"two different ids resolving to two different targets is accepted",
+			"[@甲](" + mentionA + ") 与 [@乙](" + mentionB + ")",
+			"[@甲](" + profile1 + ") 与 [@乙](" + profile2 + ")",
+			true,
+		},
+	} {
+		t.Run(tc.name, func(t *testing.T) {
+			got := verifyUpdatedDocumentContent(
+				map[string]any{"markdown": tc.actual}, tc.expected, "overwrite", "markdown")
+			if got != tc.want {
+				t.Fatalf("verify = %v, want %v\nexpected=%q\nactual=%q", got, tc.want, tc.expected, tc.actual)
+			}
+		})
+	}
+
+	if got := docFingerprintLinkDestination(docFingerprintLinkTokenPrefix + profile1 + "\x00"); got != profile1 {
+		t.Fatalf("destination extraction = %q", got)
+	}
+	if got := docFingerprintLinkDestination("open\x00link:bare"); got != "bare" {
+		t.Fatalf("a token without a title separator must still yield its destination: %q", got)
+	}
+}