feat(sync): separate full-generation Android trigger

android/app/src/main/java/com/labfytools/trainlog/data/ExchangeSafTree.kt

@@ -39,6 +39,7 @@ internal fun canonicalExchangeDirectory(): File =
 internal fun exchangeArtifactIdentity(displayName: String): String = when (displayName) {
     "trainlog-exercise-body-zones-v1.json" -> "BODY_ZONES"
     "trainlog-sync-request-v1.json" -> "SYNC_REQUEST"
+    "trainlog-sync-full-generation-request-v1.json" -> "FULL_GENERATION_SYNC_REQUEST"
     "trainlog-mobile-export-v3.json" -> "MOBILE_EXPORT"
     "trainlog-mobile-equipment-definitions-v1.json" -> "EQUIPMENT_DEFINITIONS"
     "trainlog-equipment-associations-v2.json" -> "EQUIPMENT_ASSOCIATIONS"

android/app/src/main/java/com/labfytools/trainlog/data/SyncGenerationForegroundCoordinator.kt

@@ -382,9 +382,9 @@ internal class SyncGenerationCoordinator(
         }
         var currentRunId: String? = null
         return try {
-            val baselineRunId = request(directory)?.optString("run_id")
             val peer = publishPeer(directory)
             phase(null, "peer_published", "android-peer-v1.json")
+            val baselineRunId = request(directory)?.optString("run_id")
             /* WHY: trainlog-syncd is intentionally driven by the established
              * Android request artifact, not by polling generation internals.
              * CONTRACT: each explicit foreground attempt publishes the peer
@@ -393,7 +393,11 @@ internal class SyncGenerationCoordinator(
              * ACK evidence remain immutable; retry creates new correlation. */
             afterPeerPublication?.let {
                 it.invoke()
-                phase(null, "legacy_trigger_published", "trainlog-sync-request-v1.json")
+                phase(
+                    null,
+                    "full_generation_trigger_published",
+                    FULL_GENERATION_REQUEST_NAME,
+                )
             }
             val deadline = System.nanoTime() + timeout.toNanos()
             val requestRaw =

android/app/src/main/java/com/labfytools/trainlog/data/SyncRequestOutbox.kt

@@ -13,6 +13,23 @@ import java.util.UUID
 import kotlinx.coroutines.Dispatchers
 import kotlinx.coroutines.withContext
 
+internal const val FULL_GENERATION_REQUEST_NAME =
+    "trainlog-sync-full-generation-request-v1.json"
+internal const val LEGACY_SYNC_REQUEST_NAME = "trainlog-sync-request-v1.json"
+
+internal data class SyncRequestIntent(
+    val requestId: String,
+    val requestedAt: String,
+) {
+    fun payload(): String =
+        JSONObject()
+            .put("format", "trainlog-sync-request")
+            .put("version", 1)
+            .put("request_id", requestId)
+            .put("requested_at", requestedAt)
+            .toString()
+}
+
 sealed interface SyncRequestResult {
     /** The full-generation coordinator completed both durable peer ACKs. */
     data class Completed(
@@ -60,39 +77,39 @@ class SyncRequestOutbox private constructor(
             return SyncRequestResult.Unsupported
         }
 
-        val requestId =
+        val intent = newIntent()
-            "sr_" +
+        return publishLegacy(snapshot, intent)
-                UUID.randomUUID()
+    }
-                    .toString()
 
-        val payload =
+    internal fun newIntent(): SyncRequestIntent =
-            JSONObject()
+        SyncRequestIntent(
-                .put(
+            requestId = "sr_${UUID.randomUUID()}",
-                    "format",
+            requestedAt = OffsetDateTime.now().toString(),
-                    "trainlog-sync-request",
+        )
-                )
-                .put(
-                    "version",
-                    1,
-                )
-                .put(
-                    "request_id",
-                    requestId,
-                )
-                .put(
-                    "requested_at",
-                    OffsetDateTime.now()
-                        .toString(),
-                )
-                .toString()
 
-        val displayName =
+    internal fun publishFullGeneration(
-            "trainlog-sync-request-v1.json"
+        snapshot: DirectExchangeSnapshot,
-        val error = snapshot.writeJson(displayName, payload)
+        intent: SyncRequestIntent,
+    ): SyncRequestResult = publish(snapshot, FULL_GENERATION_REQUEST_NAME, intent)
+
+    internal fun publishLegacy(
+        snapshot: DirectExchangeSnapshot,
+        intent: SyncRequestIntent,
+    ): SyncRequestResult = publish(snapshot, LEGACY_SYNC_REQUEST_NAME, intent)
+
+    private fun publish(
+        snapshot: DirectExchangeSnapshot,
+        displayName: String,
+        intent: SyncRequestIntent,
+    ): SyncRequestResult {
+        if (Build.VERSION.SDK_INT < Build.VERSION_CODES.Q) {
+            return SyncRequestResult.Unsupported
+        }
+        val error = snapshot.writeJson(displayName, intent.payload())
         return if (error == null) {
             try {
                 visibility.confirm(listOf(java.io.File(canonicalExchangeDirectory(), displayName)))
-                SyncRequestResult.Requested(requestId)
+                SyncRequestResult.Requested(intent.requestId)
             } catch (error: Exception) {
                 SyncRequestResult.Error(error.message ?: "Publication MTP impossible.")
             }

android/app/src/main/java/com/labfytools/trainlog/ui/SyncScreen.kt

@@ -60,29 +60,29 @@ internal suspend fun publishBundleAndRequest(
     terminalLedger: BackgroundSyncRunLedger? = null,
 ): SyncRequestResult = withContext(Dispatchers.IO) {
     try {
-        val opened = exporter.openStorageSnapshot()
-        if (opened is com.labfytools.trainlog.data.DirectExchangeSnapshotResult.Error) {
-            return@withContext SyncRequestResult.Error("prepare:${opened.message}")
-        }
-        val snapshot =
-            (opened as com.labfytools.trainlog.data.DirectExchangeSnapshotResult.Ready).snapshot
-        /* CONTRACT: the request signal remains compatible with an unconfigured
-         * desktop, so publish the strict standalone V3 snapshot before admission.
-         * A configured daemon still routes the signal exclusively to the complete
-         * generation below; this compatibility publication never selects V3. */
-        when (val publication = exporter.exportMobileBundle(snapshot)) {
-            SyncExportResult.Unsupported -> return@withContext SyncRequestResult.Unsupported
-            is SyncExportResult.Error ->
-                return@withContext SyncRequestResult.Error("prepare:${publication.message}")
-            is SyncExportResult.Exported -> Unit
-        }
         val directory = canonicalExchangeDirectory()
         val coordinator = SyncGenerationForegroundCoordinator(repository, visibility)
         return@withContext when (
             val result = coordinator.run(
                 directory,
                 afterPeerPublication = {
-                    when (val request = requestOutbox.requestSync(snapshot)) {
+                    val opened = exporter.openStorageSnapshot()
+                    if (opened is com.labfytools.trainlog.data.DirectExchangeSnapshotResult.Error) {
+                        throw IllegalStateException(opened.message)
+                    }
+                    val snapshot =
+                        (opened as com.labfytools.trainlog.data.DirectExchangeSnapshotResult.Ready)
+                            .snapshot
+                    val requestIntent = requestOutbox.newIntent()
+                    /* WHY: a strict V3 snapshot cannot represent causal
+                     * tombstones, but the complete generation can. CONTRACT:
+                     * publish and confirm the modern trigger before attempting
+                     * optional legacy compatibility. INVARIANT: an old desktop
+                     * sees this intent only after a fresh V3 bundle succeeds. */
+                    when (
+                        val request =
+                            requestOutbox.publishFullGeneration(snapshot, requestIntent)
+                    ) {
                         is SyncRequestResult.Requested -> Unit
                         SyncRequestResult.Unsupported ->
                             throw IllegalStateException("Generation synchronization is unsupported.")
@@ -90,6 +90,27 @@ internal suspend fun publishBundleAndRequest(
                         is SyncRequestResult.Completed ->
                             throw IllegalStateException("Unexpected completed request signal.")
                     }
+                    when (exporter.exportMobileBundle(snapshot)) {
+                        is SyncExportResult.Exported ->
+                            when (requestOutbox.publishLegacy(snapshot, requestIntent)) {
+                                is SyncRequestResult.Requested ->
+                                    logDirectExchange(
+                                        "trainlog-sync-request-v1.json",
+                                        "legacy_compatibility_published",
+                                    )
+                                else ->
+                                    logDirectExchange(
+                                        "trainlog-sync-request-v1.json",
+                                        "legacy_compatibility_unavailable",
+                                    )
+                            }
+                        SyncExportResult.Unsupported,
+                        is SyncExportResult.Error ->
+                            logDirectExchange(
+                                "trainlog-sync-request-v1.json",
+                                "legacy_compatibility_unavailable",
+                            )
+                    }
                 },
                 intent = SyncConversationIntent.NEW_EXPLICIT,
                 explicitClaim = explicitClaim,

android/app/src/test/java/com/labfytools/trainlog/data/SyncDeploymentConversationTest.kt

@@ -177,7 +177,7 @@ class SyncDeploymentConversationTest {
                     tracePhases.containsAll(
                         listOf(
                             "peer_published",
-                            "legacy_trigger_published",
+                            "full_generation_trigger_published",
                             "generation_request_observed",
                             "archive_ack_observed",
                             "generation_capture_started",

android/app/src/test/java/com/labfytools/trainlog/data/SyncRequestOutboxTest.kt

@@ -3,6 +3,7 @@ package com.labfytools.trainlog.data
 import java.nio.file.Files
 import org.json.JSONObject
 import org.junit.Assert.assertNotEquals
+import org.junit.Assert.assertEquals
 import org.junit.Assert.assertTrue
 import org.junit.Test
 import org.junit.runner.RunWith
@@ -32,4 +33,27 @@ class SyncRequestOutboxTest {
             directory.deleteRecursively()
         }
     }
+
+    @Test
+    fun oneIntentUsesSameIdentityAcrossFullGenerationAndLegacyChannels() {
+        val directory = Files.createTempDirectory("trainlog-dual-request-").toFile()
+        try {
+            val outbox = SyncRequestOutbox { directExchangeDirectoryForPath(directory) }
+            val snapshot =
+                (DirectExchangePublisher { directExchangeDirectoryForPath(directory) }.snapshot()
+                    as DirectExchangeSnapshotResult.Ready).snapshot
+            val intent = outbox.newIntent()
+
+            assertTrue(outbox.publishFullGeneration(snapshot, intent) is SyncRequestResult.Requested)
+            assertTrue(outbox.publishLegacy(snapshot, intent) is SyncRequestResult.Requested)
+
+            val full = JSONObject(java.io.File(directory, FULL_GENERATION_REQUEST_NAME).readText())
+            val legacy = JSONObject(java.io.File(directory, LEGACY_SYNC_REQUEST_NAME).readText())
+            assertEquals(intent.requestId, full.getString("request_id"))
+            assertEquals(intent.requestId, legacy.getString("request_id"))
+            assertEquals(full.toString(), legacy.toString())
+        } finally {
+            directory.deleteRecursively()
+        }
+    }
 }

tests/test_syncd_routing.py

@@ -126,17 +126,65 @@ class SyncdRoutingTest(unittest.TestCase):
             self.assertEqual(1, len(commands))
             self.assertEqual("sy_old", json.loads(state.read_text())["run_id"])
 
-    def test_android_production_trigger_no_longer_uses_opt_in_or_legacy_export(self):
+    def test_android_production_publishes_full_generation_before_optional_legacy(self):
         source = (ROOT / "android/app/src/main/java/com/labfytools/trainlog/ui/SyncScreen.kt").read_text()
         production = source.split("internal suspend fun publishBundleAndRequest", 1)[1].split(
             "internal suspend fun publishLegacyBundleAndRequest", 1
         )[0]
-        self.assertIn(
+        self.assertIn("coordinator.run", production)
-            "SyncGenerationForegroundCoordinator(repository, visibility).run", production
-        )
         self.assertNotIn("generation-opt-in", production)
         self.assertIn("exportMobileBundle", production)
-        self.assertIn("generation below", production)
+        self.assertLess(
+            production.index("publishFullGeneration"), production.index("exportMobileBundle")
+        )
+        self.assertGreater(
+            production.index("publishLegacy"), production.index("exportMobileBundle")
+        )
+
+    def test_full_generation_wins_and_retires_older_legacy(self):
+        with tempfile.TemporaryDirectory() as directory:
+            root = Path(directory)
+            old = "sr_11111111-1111-4111-8111-111111111111"
+            new = "sr_22222222-2222-4222-8222-222222222222"
+            self._write_request(root / syncd.REQUEST_NAME, old, "2026-09-20T11:00:00Z")
+            self._write_request(
+                root / syncd.FULL_GENERATION_REQUEST_NAME, new, "2026-09-20T12:00:00Z"
+            )
+            selected = syncd.select_request(root, [])
+            self.assertEqual((new, "full_generation", [old]), selected)
+            self.assertIsNone(syncd.select_request(root, [old, new]))
+
+    def test_dual_channel_same_intent_is_one_request(self):
+        with tempfile.TemporaryDirectory() as directory:
+            root = Path(directory)
+            request = "sr_22222222-2222-4222-8222-222222222222"
+            for name in (syncd.REQUEST_NAME, syncd.FULL_GENERATION_REQUEST_NAME):
+                self._write_request(root / name, request, "2026-09-20T12:00:00Z")
+            self.assertEqual(
+                (request, "full_generation", []), syncd.select_request(root, [])
+            )
+            self.assertIsNone(syncd.select_request(root, [request]))
+
+    def test_newer_legacy_remains_eligible_after_full_generation(self):
+        with tempfile.TemporaryDirectory() as directory:
+            root = Path(directory)
+            full = "sr_22222222-2222-4222-8222-222222222222"
+            legacy = "sr_33333333-3333-4333-8333-333333333333"
+            self._write_request(
+                root / syncd.FULL_GENERATION_REQUEST_NAME, full, "2026-09-20T12:00:00Z"
+            )
+            self._write_request(root / syncd.REQUEST_NAME, legacy, "2026-09-20T13:00:00Z")
+            self.assertEqual((full, "full_generation", []), syncd.select_request(root, []))
+            self.assertEqual((legacy, "legacy", [full]), syncd.select_request(root, [full]))
+
+    @staticmethod
+    def _write_request(path, request_id, requested_at):
+        path.write_text(json.dumps({
+            "format": "trainlog-sync-request",
+            "version": 1,
+            "request_id": request_id,
+            "requested_at": requested_at,
+        }))
 
 
 if __name__ == "__main__":

tools/trainlog_syncd.py

@@ -19,6 +19,8 @@ from pathlib import Path
 
 STOP = False
 REQUEST_NAME = "trainlog-sync-request-v1.json"
+FULL_GENERATION_REQUEST_NAME = "trainlog-sync-full-generation-request-v1.json"
+SEEN_REQUEST_LIMIT = 64
 REQUEST_ID = re.compile(r"sr_[0-9a-f]{8}-[0-9a-f]{4}-4[0-9a-f]{3}-[89ab][0-9a-f]{3}-[0-9a-f]{12}")
 
 
@@ -90,7 +92,7 @@ def load_generation_config(path: Path) -> dict:
     return value
 
 
-def request_id(path: Path) -> str | None:
+def request(path: Path) -> tuple[str, datetime] | None:
     try:
         value = json.loads(path.read_text(encoding="utf-8"))
     except (OSError, UnicodeError, json.JSONDecodeError):
@@ -106,7 +108,58 @@ def request_id(path: Path) -> str | None:
         and isinstance(candidate, str)
         and REQUEST_ID.fullmatch(candidate)
     ):
-        return candidate
+        requested_at = value.get("requested_at")
+        if not isinstance(requested_at, str):
+            return None
+        try:
+            timestamp = datetime.fromisoformat(requested_at.replace("Z", "+00:00"))
+        except ValueError:
+            return None
+        if timestamp.tzinfo is None:
+            return None
+        return candidate, timestamp
+    return None
+
+
+def load_request_state(path: Path) -> tuple[dict, list[str]]:
+    try:
+        state = json.loads(path.read_text(encoding="utf-8"))
+    except (OSError, UnicodeError, json.JSONDecodeError):
+        return {}, []
+    if not isinstance(state, dict):
+        return {}, []
+    seen = [item for item in state.get("seen_request_ids", [])
+            if isinstance(item, str) and REQUEST_ID.fullmatch(item)]
+    historical = state.get("request_id")
+    if isinstance(historical, str) and REQUEST_ID.fullmatch(historical) and historical not in seen:
+        seen.append(historical)
+    return state, seen[-SEEN_REQUEST_LIMIT:]
+
+
+def select_request(root: Path, seen: list[str]) -> tuple[str, str, list[str]] | None:
+    """Select one unseen intent while preventing an older cross-channel replay.
+
+    WHY: modern Android may publish the same intent on full-generation and
+    legacy channels, while stale legacy files remain durable on MTP. CONTRACT:
+    full-generation wins and an older alternate intent is retired. INVARIANT:
+    one request_id starts at most one daemon conversation.
+    """
+    full = request(root / FULL_GENERATION_REQUEST_NAME)
+    legacy = request(root / REQUEST_NAME)
+    unseen_full = full if full is not None and full[0] not in seen else None
+    unseen_legacy = legacy if legacy is not None and legacy[0] not in seen else None
+    if unseen_full is not None:
+        selected_id, selected_at = unseen_full
+        retired = list(seen)
+        if (
+            unseen_legacy is not None
+            and unseen_legacy[0] != selected_id
+            and unseen_legacy[1] <= selected_at
+        ):
+            retired.append(unseen_legacy[0])
+        return selected_id, "full_generation", retired
+    if unseen_legacy is not None:
+        return unseen_legacy[0], "legacy", list(seen)
     return None
 
 
@@ -123,16 +176,13 @@ def run_full_generation(args: argparse.Namespace, config_path: Path) -> int:
     )
     if pull.returncode != 0:
         return 3
-    correlated_request = request_id(root / REQUEST_NAME)
+    _, seen = load_request_state(args.state)
-    if correlated_request is None:
+    selected = select_request(root, seen)
+    if selected is None:
         return 3
-    if args.state.is_file():
+    correlated_request, request_channel, seen = selected
-        try:
+    seen.append(correlated_request)
-            previous = json.loads(args.state.read_text(encoding="utf-8"))
+    seen = list(dict.fromkeys(seen))[-SEEN_REQUEST_LIMIT:]
-            if previous.get("request_id") == correlated_request:
-                return 3
-        except (OSError, UnicodeError, json.JSONDecodeError):
-            pass
     run_id = "sy_" + str(uuid.uuid4())
     now = datetime.now(timezone.utc).isoformat()
     atomic_json(
@@ -142,6 +192,8 @@ def run_full_generation(args: argparse.Namespace, config_path: Path) -> int:
             "version": 1,
             "run_id": run_id,
             "request_id": correlated_request,
+            "request_channel": request_channel,
+            "seen_request_ids": seen,
             "trigger": args.trigger,
             "requested_mode": "full_generation_v1",
             "effective_mode": "full_generation_v1",

tui/src/generation_mtp.c

@@ -602,6 +602,18 @@ TrainlogStatus trainlog_generation_mtp_pull(const TrainlogGenerationMtpIo *io,
         status = pull_named_file(
             io, &selection, selection.root, "trainlog-sync-request-v1.json", local, false);
     }
+    if (status == TRAINLOG_STATUS_OK) {
+        /* WHY: strict legacy V3 may be unavailable while a complete causal
+         * generation remains valid. CONTRACT: pull the dedicated bounded
+         * coordination object without scanning the exchange tree. INVARIANT:
+         * this read never acknowledges, deletes, or rewrites remote state. */
+        status = pull_named_file(io,
+                                 &selection,
+                                 selection.root,
+                                 "trainlog-sync-full-generation-request-v1.json",
+                                 local,
+                                 false);
+    }
     if (status == TRAINLOG_STATUS_OK) {
         status = pull_named_file(
             io, &selection, selection.root, "android-generation-v1.json", local, false);

tui/tests/test_generation_mtp.c

@@ -244,6 +244,12 @@ static int test_pull_and_manifest_last(void) {
         "trainlog-sync-request-v1.json",
         "{\"format\":\"trainlog-sync-request\",\"version\":1,\"request_id\":\"sr_11111111-"
         "1111-4111-8111-111111111111\",\"requested_at\":\"2026-09-20T12:00:00Z\"}");
+    add(14,
+        2,
+        false,
+        "trainlog-sync-full-generation-request-v1.json",
+        "{\"format\":\"trainlog-sync-request\",\"version\":1,\"request_id\":\"sr_11111111-"
+        "1111-4111-8111-111111111111\",\"requested_at\":\"2026-09-20T12:00:00Z\"}");
     add(5, 2, true, "android-objects", NULL);
     add(6, 5, true, "generations", NULL);
     add(7, 6, true, "gen_11111111-1111-4111-8111-111111111111", NULL);
@@ -261,6 +267,9 @@ static int test_pull_and_manifest_last(void) {
         root,
         "android-objects/generations/gen_11111111-1111-4111-8111-111111111111/payload.json"));
     CHECK(access(path, R_OK) == 0);
+    CHECK(trainlog_test_join_path(
+        path, sizeof(path), root, "trainlog-sync-full-generation-request-v1.json"));
+    CHECK(access(path, R_OK) == 0);
     CHECK(trainlog_test_join_path(path, sizeof(path), root, "trainlog-sync-request-v1.json"));
     CHECK(access(path, R_OK) == 0);
     CHECK(trainlog_test_join_path(path, sizeof(path), root, "out"));