diff --git a/Packages/WhoopStore/Tests/WhoopStoreTests/Resources/schema_oracle.json b/Packages/WhoopStore/Tests/WhoopStoreTests/Resources/schema_oracle.json
index 72081fadf5..0de99c3e75 100644
--- a/Packages/WhoopStore/Tests/WhoopStoreTests/Resources/schema_oracle.json
+++ b/Packages/WhoopStore/Tests/WhoopStoreTests/Resources/schema_oracle.json
@@ -1,5 +1,5 @@
 {
-  "_readme": "SHARED Room<->GRDB SCHEMA ORACLE (#775). Two byte-identical copies: Packages/WhoopStore/Tests/WhoopStoreTests/Resources/schema_oracle.json and android/app/src/test/resources/schema_oracle.json. SchemaOracleTests.swift compares GRDB's PRAGMA table_info/index_list against it; SchemaOracleTest.kt compares Room's exported schema JSON against it. `columns` is the iOS/GRDB shape in GRDB column order (macOS is the reference implementation); every way Android differs is spelled out in an `android` / `iosAbsent` / `androidColumnOrder` override naming a key in `divergenceReasons`. Adding a column, reordering one, or changing a type/nullability on one platform only fails both suites until it is either fixed or written down here.",
+  "_readme": "SHARED Room<->GRDB SCHEMA ORACLE (#775). Two byte-identical copies: Packages/WhoopStore/Tests/WhoopStoreTests/Resources/schema_oracle.json and android/app/src/test/resources/schema_oracle.json. SchemaOracleTests.swift compares GRDB's PRAGMA table_info/index_list against it; SchemaOracleTest.kt compares Room's exported schema JSON against it. `columns` is the iOS/GRDB shape in GRDB column order (macOS is the reference implementation); every way Android differs is spelled out in an `android` / `iosAbsent` / `androidColumnOrder` override naming a key in `divergenceReasons`. Adding a column, reordering one, or changing a type/nullability on one platform only fails both suites until it is either fixed or written down here. The optional `grdbMigrationLineages` is the same idea for migration IDENTIFIERS: a fork or long-lived branch that numbered its own migrations before upstream reached those numbers declares them there instead of renumbering \u2014 GRDB keys migrations by identifier string, so renaming one wedges a database that already ran it. Whatever is not declared is the baseline lineage and is still checked as exactly v1..vN.",
   "roomVersion": 25,
   "grdbMigrations": [
     "v1",
diff --git a/Packages/WhoopStore/Tests/WhoopStoreTests/SchemaOracleTests.swift b/Packages/WhoopStore/Tests/WhoopStoreTests/SchemaOracleTests.swift
index 5cba234060..30853408ae 100644
--- a/Packages/WhoopStore/Tests/WhoopStoreTests/SchemaOracleTests.swift
+++ b/Packages/WhoopStore/Tests/WhoopStoreTests/SchemaOracleTests.swift
@@ -32,6 +32,15 @@ final class SchemaOracleTests: XCTestCase {
         let grdbMigrations: [String]
         let divergenceReasons: [String: String]
         let tables: [String: OracleTable]
+        /// Absent upstream, where there is only the baseline lineage. See `MigrationLineage`.
+        let grdbMigrationLineages: [String: MigrationLineage]?
+        var lineages: [String: MigrationLineage] { grdbMigrationLineages ?? [:] }
+    }
+    /// A set of migration identifiers numbered independently of the baseline lineage — a fork that
+    /// reached `vN` before upstream did. Declaring one is what lets the two coexist without a renumber.
+    struct MigrationLineage: Decodable {
+        let reason: String
+        let migrations: [String]
     }
     struct OracleTable: Decodable {
         let platform: String                 // "both" | "ios_only" | "android_only"
@@ -201,23 +210,58 @@ final class SchemaOracleTests: XCTestCase {
     /// entirely, because the first already recorded that name in `grdb_migrations`.
     ///
     /// So: identifiers unique, and their `vN` prefixes exactly 1...N with no gaps and no repeats.
+    ///
+    /// The one sanctioned exception is a DECLARED lineage. A fork that numbered its own migrations
+    /// before upstream reached those numbers cannot renumber its way out — GRDB keys by identifier
+    /// string, so renaming one makes it read as un-applied on a device that already ran it and the
+    /// migrator re-runs its body against a schema that already has the table. Such a fork lists its
+    /// identifiers under `grdbMigrationLineages`; everything NOT listed is the baseline lineage and is
+    /// still held to exactly v1...vN. So the escape hatch costs a written-down reason and cannot be
+    /// taken by accident — an undeclared collision still fails, which is what catches #369 vs #475.
     func testGrdbMigrationIdentifiersAreUniqueAndSequential() throws {
+        let oracle = try loadOracle()
         let ids = WhoopStore.makeMigrator().migrations
         XCTAssertEqual(Set(ids).count, ids.count,
                        "duplicate GRDB migration identifier — GRDB would silently SKIP the second body")
 
-        var numbers: [Int] = []
-        for id in ids {
-            let digits = id.dropFirst().prefix { $0.isNumber }
-            guard id.hasPrefix("v"), let n = Int(digits) else {
-                return XCTFail("migration identifier '\(id)' is not of the form v<N>[-slug]")
+        func version(of id: String) -> Int? {
+            guard id.hasPrefix("v"), let n = Int(id.dropFirst().prefix(while: \.isNumber)) else { return nil }
+            return n
+        }
+        for id in ids where version(of: id) == nil {
+            return XCTFail("migration identifier '\(id)' is not of the form v<N>[-slug]")
+        }
+
+        // A declared lineage must be true (every member registered) and self-consistent (its own vN
+        // strictly increasing), so the ledger can only shrink deliberately — same rule the divergence
+        // reasons live by.
+        var claimedBy: [String: String] = [:]
+        for (name, lineage) in oracle.lineages.sorted(by: { $0.key < $1.key }) {
+            XCTAssertFalse(lineage.migrations.isEmpty, "lineage '\(name)' declares no migrations — delete it")
+            for id in lineage.migrations {
+                if let other = claimedBy.updateValue(name, forKey: id) {
+                    return XCTFail("'\(id)' is claimed by both lineage '\(other)' and '\(name)'")
+                }
+                guard ids.contains(id) else {
+                    return XCTFail("lineage '\(name)' declares '\(id)', which is not registered — a lineage "
+                                   + "entry that stopped being true must be deleted, not left to rot")
+                }
+            }
+            let numbers = lineage.migrations.compactMap(version(of:))
+            for (a, b) in zip(numbers, numbers.dropFirst()) where b <= a {
+                return XCTFail("lineage '\(name)' goes v\(a) then v\(b) — a lineage numbers its own "
+                               + "migrations, so its vN must strictly increase")
             }
-            numbers.append(n)
         }
-        for (offset, n) in numbers.enumerated() where n != offset + 1 {
-            return XCTFail("GRDB migration '\(ids[offset])' claims v\(n) but is #\(offset + 1) in "
-                           + "registration order — two migrations claiming the same vN, or a gap, makes the "
-                           + "GRDB-name <-> Room-version mapping ambiguous. Renumber before merging.")
+
+        let baseline = ids.filter { claimedBy[$0] == nil }
+        for (offset, id) in baseline.enumerated() where version(of: id) != offset + 1 {
+            return XCTFail("GRDB migration '\(id)' claims v\(version(of: id)!) but is #\(offset + 1) in the "
+                           + "BASELINE lineage (registration order minus every lineage schema_oracle.json "
+                           + "declares) — two migrations claiming the same vN, or a gap, makes the "
+                           + "GRDB-name <-> Room-version mapping ambiguous. Renumber before merging, or, if "
+                           + "the identifier already shipped and renaming it would wedge a live database, "
+                           + "declare it in grdbMigrationLineages with a reason.")
         }
     }
 
diff --git a/android/app/src/test/java/com/noop/data/SchemaOracleTest.kt b/android/app/src/test/java/com/noop/data/SchemaOracleTest.kt
index 14aec7c2f4..a482a41d4b 100644
--- a/android/app/src/test/java/com/noop/data/SchemaOracleTest.kt
+++ b/android/app/src/test/java/com/noop/data/SchemaOracleTest.kt
@@ -238,25 +238,67 @@ class SchemaOracleTest {
      * migrations by NAME and applies them in registration order; Room keys by integer version, so the
      * only thing that can be compared mechanically is the RESULTING schema — which is what the tests
      * above do. Pinning the two identifier spaces is what forces them to be re-checked together.
+     *
+     * The one sanctioned exception is a DECLARED lineage. A fork that numbered its own migrations before
+     * upstream reached those numbers cannot renumber its way out — GRDB keys by identifier string, so
+     * renaming one makes it read as un-applied on a device that already ran it. Such a fork lists its
+     * identifiers under `grdbMigrationLineages`; everything NOT listed is the baseline lineage and is
+     * still held to exactly v1..vN. An UNDECLARED collision still fails, which is the #369-vs-#475 case.
+     * Mirrors `testGrdbMigrationIdentifiersAreUniqueAndSequential` in the Swift half.
      */
     @Test
     fun pinnedMigrationIdentifiersAreCoherent() {
         val oracle = loadOracle()
         val grdb = oracle.getJSONArray("grdbMigrations").strings()
         assertEquals("duplicate GRDB migration identifier in schema_oracle.json", grdb.size, grdb.toSet().size)
-        grdb.forEachIndexed { i, id ->
-            val n = id.removePrefix("v").takeWhile { it.isDigit() }.toIntOrNull()
+
+        // A declared lineage must be true (every member pinned) and self-consistent (its own vN strictly
+        // increasing), so the ledger can only shrink deliberately — same rule the divergence reasons live by.
+        val lineages = oracle.optJSONObject("grdbMigrationLineages") ?: JSONObject()
+        val claimedBy = HashMap<String, String>()
+        for (name in lineages.keys().asSequence().sorted()) {
+            val migrations = lineages.getJSONObject(name).getJSONArray("migrations").strings()
+            assertTrue("lineage '$name' declares no migrations — delete it", migrations.isNotEmpty())
+            val numbers = migrations.map { id ->
+                val other = claimedBy.put(id, name)
+                assertTrue("'$id' is claimed by both lineage '$other' and '$name'", other == null)
+                assertTrue(
+                    "lineage '$name' declares '$id', which is not in grdbMigrations — a lineage entry that " +
+                        "stopped being true must be deleted, not left to rot",
+                    grdb.contains(id),
+                )
+                val n = migrationVersion(id)
+                assertNotNull("lineage '$name' member '$id' is not of the form v<N>[-slug]", n)
+                n!!
+            }
+            numbers.zipWithNext { a, b ->
+                assertTrue(
+                    "lineage '$name' goes v$a then v$b — a lineage numbers its own migrations, so its vN " +
+                        "must strictly increase",
+                    b > a,
+                )
+            }
+        }
+
+        grdb.filterNot { claimedBy.containsKey(it) }.forEachIndexed { i, id ->
             assertEquals(
-                "GRDB migration '$id' claims v$n but is #${i + 1} in registration order — two migrations " +
-                    "claiming the same vN, or a gap, makes the GRDB-name <-> Room-version mapping ambiguous.",
+                "GRDB migration '$id' claims v${migrationVersion(id)} but is #${i + 1} in the BASELINE " +
+                    "lineage (grdbMigrations minus every lineage grdbMigrationLineages declares) — two " +
+                    "migrations claiming the same vN, or a gap, makes the GRDB-name <-> Room-version " +
+                    "mapping ambiguous. Renumber before merging, or, if the identifier already shipped and " +
+                    "renaming it would wedge a live database, declare it in grdbMigrationLineages.",
                 i + 1,
-                n,
+                migrationVersion(id),
             )
         }
         // loadRoomSchema asserts the exported version equals this; call it so the check is not vacuous.
         loadRoomSchema(oracle.getInt("roomVersion"))
     }
 
+    /** The `N` of a `v<N>[-slug]` migration identifier, or null if it is not of that form. */
+    private fun migrationVersion(id: String): Int? =
+        id.removePrefix("v").takeWhile { it.isDigit() }.toIntOrNull()
+
     /**
      * The Android and Swift copies of the oracle MUST be byte-identical, so neither platform can edit its
      * fixture without the other. Skips gracefully if the Swift tree isn't present.
diff --git a/android/app/src/test/resources/schema_oracle.json b/android/app/src/test/resources/schema_oracle.json
index 72081fadf5..0de99c3e75 100644
--- a/android/app/src/test/resources/schema_oracle.json
+++ b/android/app/src/test/resources/schema_oracle.json
@@ -1,5 +1,5 @@
 {
-  "_readme": "SHARED Room<->GRDB SCHEMA ORACLE (#775). Two byte-identical copies: Packages/WhoopStore/Tests/WhoopStoreTests/Resources/schema_oracle.json and android/app/src/test/resources/schema_oracle.json. SchemaOracleTests.swift compares GRDB's PRAGMA table_info/index_list against it; SchemaOracleTest.kt compares Room's exported schema JSON against it. `columns` is the iOS/GRDB shape in GRDB column order (macOS is the reference implementation); every way Android differs is spelled out in an `android` / `iosAbsent` / `androidColumnOrder` override naming a key in `divergenceReasons`. Adding a column, reordering one, or changing a type/nullability on one platform only fails both suites until it is either fixed or written down here.",
+  "_readme": "SHARED Room<->GRDB SCHEMA ORACLE (#775). Two byte-identical copies: Packages/WhoopStore/Tests/WhoopStoreTests/Resources/schema_oracle.json and android/app/src/test/resources/schema_oracle.json. SchemaOracleTests.swift compares GRDB's PRAGMA table_info/index_list against it; SchemaOracleTest.kt compares Room's exported schema JSON against it. `columns` is the iOS/GRDB shape in GRDB column order (macOS is the reference implementation); every way Android differs is spelled out in an `android` / `iosAbsent` / `androidColumnOrder` override naming a key in `divergenceReasons`. Adding a column, reordering one, or changing a type/nullability on one platform only fails both suites until it is either fixed or written down here. The optional `grdbMigrationLineages` is the same idea for migration IDENTIFIERS: a fork or long-lived branch that numbered its own migrations before upstream reached those numbers declares them there instead of renumbering \u2014 GRDB keys migrations by identifier string, so renaming one wedges a database that already ran it. Whatever is not declared is the baseline lineage and is still checked as exactly v1..vN.",
   "roomVersion": 25,
   "grdbMigrations": [
     "v1",