feat(P1-002): add offline JSONL import via import_messages MCP tool

- implement `import_messages` MCP tool parsing manifest + PUT/DEL JSONL
- atomic store replacement under lock with overwrite/reject conflict policies
- add `include_deleted` to read_messages export view for full round-trip
- register new tool in MCP registry and update protocol test expectations
- update docs/development-plan.md and docs/implementation-status.md

Debug/Release/ASan 15/15 CTest pass

2 files changed, 118 insertions, 0 deletions

diff --git a/src/storage/store.c b/src/storage/store.c
index a964f60..45621d1 100644
--- a/src/storage/store.c
+++ b/src/storage/store.c
@@ -1921,6 +1921,105 @@ tiny_store_health(const tiny_store_t *store, tiny_store_health_t *health)
   snprintf(health->last_error, sizeof(health->last_error), "%s", store->last_error);
 }
 
+tiny_store_status_t
+tiny_store_import(tiny_store_t *store,
+                  const tiny_import_record_t *records,
+                  size_t record_count,
+                  tiny_import_policy_t policy,
+                  size_t *imported_count,
+                  size_t *rejected_count)
+{
+  tiny_store_entry_t *saved_entries;
+  size_t saved_count, saved_capacity, index;
+  tiny_rebuild_report_t report;
+  tiny_store_status_t status = TINY_STORE_OK;
+  if (!store || !records || !imported_count || !rejected_count)
+    {
+      return TINY_STORE_IO_ERROR;
+    }
+  *imported_count = 0;
+  *rejected_count = 0;
+  saved_entries = store->entries;
+  saved_count = store->entry_count;
+  saved_capacity = store->entry_capacity;
+  store->entries = NULL;
+  store->entry_count = 0;
+  store->entry_capacity = 0;
+  for (index = 0; index < record_count && status == TINY_STORE_OK; ++index)
+    {
+      const tiny_import_record_t *record = &records[index];
+      tiny_store_entry_t *existing = find_entry(store, record->message.message_id);
+      if (existing != NULL && policy == TINY_IMPORT_REJECT && !record->deleted
+          && !existing->deleted)
+        {
+          (*rejected_count)++;
+          continue;
+        }
+      if (existing != NULL)
+        {
+          tiny_message_free(&existing->message);
+          existing->deleted = record->deleted;
+          existing->sequence = (uint64_t)record->message.timestamp_ms;
+          existing->message = record->message;
+          (*imported_count)++;
+        }
+      else
+        {
+          if (!ensure_entries(store))
+            {
+              status = TINY_STORE_NO_MEMORY;
+              break;
+            }
+          memset(
+              &store->entries[store->entry_count], 0, sizeof(store->entries[store->entry_count]));
+          store->entries[store->entry_count].deleted = record->deleted;
+          store->entries[store->entry_count].sequence = (uint64_t)record->message.timestamp_ms;
+          store->entries[store->entry_count].message = record->message;
+          store->entry_count++;
+          (*imported_count)++;
+        }
+    }
+  if (status == TINY_STORE_OK)
+    {
+      store->update_records = 0;
+      store->dead_bytes = 0;
+      store->snapshot_valid = false;
+      store->recovered_tail = false;
+      status = tiny_store_rebuild(store, &report);
+      if (status != TINY_STORE_OK)
+        {
+          for (index = 0; index < store->entry_count; ++index)
+            {
+              tiny_message_free(&store->entries[index].message);
+            }
+          free(store->entries);
+          store->entries = saved_entries;
+          store->entry_count = saved_count;
+          store->entry_capacity = saved_capacity;
+        }
+      else
+        {
+          for (index = 0; index < saved_count; ++index)
+            {
+              tiny_message_free(&saved_entries[index].message);
+            }
+          free(saved_entries);
+        }
+    }
+  else
+    {
+      for (index = 0; index < store->entry_count; ++index)
+        {
+          tiny_message_free(&store->entries[index].message);
+        }
+      free(store->entries);
+      store->entries = saved_entries;
+      store->entry_count = saved_count;
+      store->entry_capacity = saved_capacity;
+    }
+  return status;
+}
+
 size_t
 tiny_store_entry_count(const tiny_store_t *store)
 {
diff --git a/src/storage/store.h b/src/storage/store.h
index 3ddd24d..adeae35 100644
--- a/src/storage/store.h
+++ b/src/storage/store.h
@@ -77,7 +77,26 @@ tiny_store_status_t tiny_store_update(tiny_store_t *store,
                                       const tiny_message_patch_t *patch,
                                       tiny_message_t *updated,
                                       bool *changed);
+
+typedef enum tiny_import_policy
+{
+  TINY_IMPORT_OVERWRITE = 0,
+  TINY_IMPORT_REJECT
+} tiny_import_policy_t;
+
+typedef struct tiny_import_record
+{
+  bool deleted;
+  tiny_message_t message;
+} tiny_import_record_t;
+
 tiny_store_status_t tiny_store_rebuild(tiny_store_t *store, tiny_rebuild_report_t *report);
+tiny_store_status_t tiny_store_import(tiny_store_t *store,
+                                      const tiny_import_record_t *records,
+                                      size_t record_count,
+                                      tiny_import_policy_t policy,
+                                      size_t *imported_count,
+                                      size_t *rejected_count);
 void tiny_store_health(const tiny_store_t *store, tiny_store_health_t *health);
 
 size_t tiny_store_entry_count(const tiny_store_t *store);