diff --git a/crud.py b/crud.py
index b542278..1e5ac73 100644
--- a/crud.py
+++ b/crud.py
@@ -1,5 +1,293 @@
+import json
+from datetime import datetime, timezone
+
 from lnbits.db import Database
+from lnbits.helpers import urlsafe_short_hash
+
+from .models import (
+    CreateTask,
+    CreateTaskCompletion,
+    Task,
+    TaskCompletion,
+    TasksSettings,
+)
 
 db = Database("ext_tasks")
 
-# CRUD functions are filled in by the next commit.
+
+def _serialize_task_jsonb(task_dict: dict) -> dict:
+    """JSON-encode the columns we store as TEXT (participants, categories,
+    recurrence) so db.insert/update sees strings, not Python objects."""
+    out = dict(task_dict)
+    if isinstance(out.get("participants"), list):
+        out["participants"] = json.dumps(
+            [p if isinstance(p, dict) else p.dict() for p in out["participants"]]
+        )
+    if isinstance(out.get("categories"), list):
+        out["categories"] = json.dumps(out["categories"])
+    rec = out.get("recurrence")
+    if rec is not None and not isinstance(rec, str):
+        out["recurrence"] = json.dumps(rec if isinstance(rec, dict) else rec.dict())
+    return out
+
+
+def _parse_task_row(row) -> dict:
+    """Decode TEXT-JSON columns back into Python structures so Pydantic can
+    rebuild the Task without each model needing a string-parser validator on
+    every read path."""
+    data = dict(row)
+    if isinstance(data.get("participants"), str):
+        data["participants"] = json.loads(data["participants"]) if data["participants"] else []
+    if isinstance(data.get("categories"), str):
+        data["categories"] = json.loads(data["categories"]) if data["categories"] else []
+    rec = data.get("recurrence")
+    if isinstance(rec, str):
+        data["recurrence"] = json.loads(rec) if rec else None
+    return data
+
+
+################################ Tasks ################################
+
+
+async def create_task(pubkey: str, data: CreateTask) -> Task:
+    """Insert a task. The d_tag is generated locally; subsequent edits keep
+    the same d_tag so the published kind 31922 stays addressable."""
+    task_id = urlsafe_short_hash()
+    d_tag = task_id
+    task = Task(
+        id=task_id,
+        wallet=data.wallet or "",
+        pubkey=pubkey,
+        d_tag=d_tag,
+        title=data.title,
+        start_date=data.start_date,
+        end_date=data.end_date,
+        description=data.description,
+        location=data.location,
+        status=data.status,
+        event_type=data.event_type,
+        participants=data.participants,
+        categories=data.categories,
+        recurrence=data.recurrence,
+        time=datetime.now(timezone.utc),
+    )
+    await db.execute(
+        """
+        INSERT INTO tasks.tasks (
+            id, wallet, pubkey, d_tag, title, start_date, end_date,
+            description, location, status, event_type, participants,
+            categories, recurrence, nostr_event_id, nostr_event_created_at,
+            time
+        ) VALUES (
+            :id, :wallet, :pubkey, :d_tag, :title, :start_date, :end_date,
+            :description, :location, :status, :event_type, :participants,
+            :categories, :recurrence, :nostr_event_id, :nostr_event_created_at,
+            :time
+        )
+        """,
+        _serialize_task_jsonb(task.dict()),
+    )
+    return task
+
+
+async def update_task(task: Task) -> Task:
+    await db.execute(
+        """
+        UPDATE tasks.tasks SET
+            wallet = :wallet,
+            title = :title,
+            start_date = :start_date,
+            end_date = :end_date,
+            description = :description,
+            location = :location,
+            status = :status,
+            event_type = :event_type,
+            participants = :participants,
+            categories = :categories,
+            recurrence = :recurrence,
+            nostr_event_id = :nostr_event_id,
+            nostr_event_created_at = :nostr_event_created_at
+        WHERE id = :id
+        """,
+        _serialize_task_jsonb(task.dict()),
+    )
+    return task
+
+
+async def get_task(task_id: str) -> Task | None:
+    row: dict | None = await db.fetchone(
+        "SELECT * FROM tasks.tasks WHERE id = :id",
+        {"id": task_id},
+    )
+    return Task(**_parse_task_row(row)) if row else None
+
+
+async def get_task_by_address(pubkey: str, d_tag: str) -> Task | None:
+    row: dict | None = await db.fetchone(
+        "SELECT * FROM tasks.tasks WHERE pubkey = :pubkey AND d_tag = :d_tag",
+        {"pubkey": pubkey, "d_tag": d_tag},
+    )
+    return Task(**_parse_task_row(row)) if row else None
+
+
+async def get_tasks(wallet_ids: str | list[str]) -> list[Task]:
+    if isinstance(wallet_ids, str):
+        wallet_ids = [wallet_ids]
+    q = ",".join([f"'{wid}'" for wid in wallet_ids])
+    rows: list[dict] = await db.fetchall(
+        f"SELECT * FROM tasks.tasks WHERE wallet IN ({q}) ORDER BY time DESC"
+    )
+    return [Task(**_parse_task_row(row)) for row in rows]
+
+
+async def get_all_tasks() -> list[Task]:
+    """Admin-only. All tasks regardless of wallet, including synced-from-Nostr
+    rows (wallet=''). Order by recency."""
+    rows: list[dict] = await db.fetchall(
+        "SELECT * FROM tasks.tasks ORDER BY time DESC"
+    )
+    return [Task(**_parse_task_row(row)) for row in rows]
+
+
+async def get_public_tasks() -> list[Task]:
+    """Public listing: all tasks. Gated upstream by the public_listing
+    settings flag."""
+    rows: list[dict] = await db.fetchall(
+        "SELECT * FROM tasks.tasks ORDER BY start_date ASC"
+    )
+    return [Task(**_parse_task_row(row)) for row in rows]
+
+
+async def get_tasks_by_pubkey(pubkey: str) -> list[Task]:
+    rows: list[dict] = await db.fetchall(
+        "SELECT * FROM tasks.tasks WHERE pubkey = :pubkey ORDER BY time DESC",
+        {"pubkey": pubkey},
+    )
+    return [Task(**_parse_task_row(row)) for row in rows]
+
+
+async def delete_task(task_id: str) -> None:
+    await db.execute("DELETE FROM tasks.tasks WHERE id = :id", {"id": task_id})
+
+
+async def delete_task_completions(task_address: str) -> None:
+    await db.execute(
+        "DELETE FROM tasks.completions WHERE task_address = :addr",
+        {"addr": task_address},
+    )
+
+
+############################# Completions #############################
+
+
+async def create_completion(
+    pubkey: str, data: CreateTaskCompletion, *, nostr_event_id: str | None = None,
+    nostr_created_at: int | None = None,
+) -> TaskCompletion:
+    """Insert (or replace on conflict) a completion for (task_address, pubkey,
+    occurrence). The newest event_id always wins — we let the caller pass an
+    already-published Nostr id, otherwise generate a local hash for an unsent
+    completion that the Nostr publisher will replace on the next round-trip."""
+    cid = nostr_event_id or urlsafe_short_hash()
+    completion = TaskCompletion(
+        id=cid,
+        task_address=data.task_address,
+        pubkey=pubkey,
+        occurrence=data.occurrence,
+        task_status=data.task_status,
+        completed_at=data.completed_at,
+        notes=data.notes,
+        nostr_created_at=nostr_created_at or int(datetime.now(timezone.utc).timestamp()),
+        time=datetime.now(timezone.utc),
+    )
+
+    # Replace any existing claim by this pubkey on this (address, occurrence).
+    existing = await get_completion(
+        data.task_address, pubkey, data.occurrence
+    )
+    if existing:
+        await db.execute(
+            "DELETE FROM tasks.completions WHERE id = :id", {"id": existing.id}
+        )
+
+    await db.execute(
+        """
+        INSERT INTO tasks.completions (
+            id, task_address, pubkey, occurrence, task_status,
+            completed_at, notes, nostr_created_at, time
+        ) VALUES (
+            :id, :task_address, :pubkey, :occurrence, :task_status,
+            :completed_at, :notes, :nostr_created_at, :time
+        )
+        """,
+        completion.dict(),
+    )
+    return completion
+
+
+async def get_completion(
+    task_address: str, pubkey: str, occurrence: str | None
+) -> TaskCompletion | None:
+    if occurrence is None:
+        row: dict | None = await db.fetchone(
+            """
+            SELECT * FROM tasks.completions
+            WHERE task_address = :addr AND pubkey = :pubkey
+              AND occurrence IS NULL
+            """,
+            {"addr": task_address, "pubkey": pubkey},
+        )
+    else:
+        row = await db.fetchone(
+            """
+            SELECT * FROM tasks.completions
+            WHERE task_address = :addr AND pubkey = :pubkey
+              AND occurrence = :occurrence
+            """,
+            {"addr": task_address, "pubkey": pubkey, "occurrence": occurrence},
+        )
+    return TaskCompletion(**dict(row)) if row else None
+
+
+async def get_completions_for_task(task_address: str) -> list[TaskCompletion]:
+    rows: list[dict] = await db.fetchall(
+        "SELECT * FROM tasks.completions WHERE task_address = :addr "
+        "ORDER BY nostr_created_at DESC",
+        {"addr": task_address},
+    )
+    return [TaskCompletion(**dict(row)) for row in rows]
+
+
+async def get_completion_by_id(completion_id: str) -> TaskCompletion | None:
+    row: dict | None = await db.fetchone(
+        "SELECT * FROM tasks.completions WHERE id = :id",
+        {"id": completion_id},
+    )
+    return TaskCompletion(**dict(row)) if row else None
+
+
+async def delete_completion(completion_id: str) -> None:
+    await db.execute(
+        "DELETE FROM tasks.completions WHERE id = :id",
+        {"id": completion_id},
+    )
+
+
+############################## Settings ##############################
+
+
+async def get_settings() -> TasksSettings:
+    row: dict | None = await db.fetchone(
+        "SELECT * FROM tasks.settings WHERE id = 1"
+    )
+    if row:
+        return TasksSettings(**dict(row))
+    return TasksSettings()
+
+
+async def update_settings(settings: TasksSettings) -> TasksSettings:
+    await db.execute(
+        "UPDATE tasks.settings SET public_listing = :public_listing WHERE id = 1",
+        {"public_listing": settings.public_listing},
+    )
+    return settings
diff --git a/migrations.py b/migrations.py
index be88854..93c27a9 100644
--- a/migrations.py
+++ b/migrations.py
@@ -1 +1,76 @@
-# Migrations are filled in by the next commit.
+async def m001_initial(db):
+    """
+    Tasks table (NIP-52 kind 31922 cache) and completions table (kind 31925
+    cache). The (pubkey, d_tag) pair is the parameterized-replaceable key.
+    """
+    await db.execute(
+        f"""
+        CREATE TABLE tasks.tasks (
+            id TEXT PRIMARY KEY,
+            wallet TEXT NOT NULL,
+            pubkey TEXT NOT NULL,
+            d_tag TEXT NOT NULL,
+            title TEXT NOT NULL,
+            start_date TEXT NOT NULL,
+            end_date TEXT,
+            description TEXT NOT NULL DEFAULT '',
+            location TEXT,
+            status TEXT NOT NULL DEFAULT 'pending',
+            event_type TEXT NOT NULL DEFAULT 'task',
+            participants TEXT,
+            categories TEXT,
+            recurrence TEXT,
+            nostr_event_id TEXT,
+            nostr_event_created_at INTEGER,
+            time TIMESTAMP NOT NULL DEFAULT {db.timestamp_now}
+        );
+    """
+    )
+    await db.execute(
+        "CREATE UNIQUE INDEX tasks_pubkey_dtag_idx "
+        "ON tasks.tasks (pubkey, d_tag)"
+    )
+
+    await db.execute(
+        f"""
+        CREATE TABLE tasks.completions (
+            id TEXT PRIMARY KEY,
+            task_address TEXT NOT NULL,
+            pubkey TEXT NOT NULL,
+            occurrence TEXT,
+            task_status TEXT NOT NULL DEFAULT 'claimed',
+            completed_at INTEGER,
+            notes TEXT NOT NULL DEFAULT '',
+            nostr_created_at INTEGER NOT NULL,
+            time TIMESTAMP NOT NULL DEFAULT {db.timestamp_now}
+        );
+    """
+    )
+    # occurrence is NULL for one-shot tasks; the (task_address, pubkey,
+    # occurrence) tuple identifies "the latest claim by this user for this
+    # specific occurrence".
+    await db.execute(
+        "CREATE INDEX tasks_completions_address_idx "
+        "ON tasks.completions (task_address)"
+    )
+    await db.execute(
+        "CREATE INDEX tasks_completions_pubkey_idx "
+        "ON tasks.completions (pubkey)"
+    )
+
+
+async def m002_settings(db):
+    """Singleton settings row for the admin UI."""
+    await db.execute(
+        """
+        CREATE TABLE IF NOT EXISTS tasks.settings (
+            id INTEGER PRIMARY KEY DEFAULT 1,
+            public_listing BOOLEAN NOT NULL DEFAULT FALSE
+        )
+        """
+    )
+    await db.execute(
+        "INSERT INTO tasks.settings (id, public_listing) "
+        "SELECT 1, FALSE WHERE NOT EXISTS "
+        "(SELECT 1 FROM tasks.settings WHERE id = 1)"
+    )
diff --git a/models.py b/models.py
index 3270f77..1874b34 100644
--- a/models.py
+++ b/models.py
@@ -1 +1,156 @@
-# Pydantic models are filled in by the next commit.
+import json
+from datetime import datetime
+from typing import Literal
+
+from pydantic import BaseModel, Field, validator
+
+
+TaskStatus = Literal["claimed", "in-progress", "completed", "blocked", "cancelled"]
+
+
+class Participant(BaseModel):
+    pubkey: str
+    type: str | None = None  # "required" | "optional" | "organizer"
+
+
+class Recurrence(BaseModel):
+    frequency: Literal["daily", "weekly"]
+    day_of_week: str | None = None  # for weekly: monday..sunday
+    end_date: str | None = None  # YYYY-MM-DD, optional cutoff
+
+
+class CreateTask(BaseModel):
+    wallet: str | None = None  # filled from caller's wallet if absent
+    title: str
+    start_date: str  # YYYY-MM-DD or ISO datetime
+    end_date: str | None = None
+    description: str = ""
+    location: str | None = None
+    status: str = "pending"
+    event_type: str = "task"  # 'task' | 'announcement'
+    participants: list[Participant] = Field(default_factory=list)
+    categories: list[str] = Field(default_factory=list)
+    recurrence: Recurrence | None = None
+
+    @validator("participants", pre=True)
+    def parse_participants(cls, v):
+        if isinstance(v, str):
+            return json.loads(v) if v else []
+        return v or []
+
+    @validator("categories", pre=True)
+    def parse_categories(cls, v):
+        if isinstance(v, str):
+            return json.loads(v) if v else []
+        return v or []
+
+    @validator("recurrence", pre=True)
+    def parse_recurrence(cls, v):
+        if isinstance(v, str):
+            return json.loads(v) if v else None
+        return v
+
+
+class Task(BaseModel):
+    id: str
+    wallet: str
+    pubkey: str
+    d_tag: str
+    title: str
+    start_date: str
+    end_date: str | None = None
+    description: str = ""
+    location: str | None = None
+    status: str = "pending"
+    event_type: str = "task"
+    participants: list[Participant] = Field(default_factory=list)
+    categories: list[str] = Field(default_factory=list)
+    recurrence: Recurrence | None = None
+    nostr_event_id: str | None = None
+    nostr_event_created_at: int | None = None
+    time: datetime
+
+    @validator("participants", pre=True)
+    def parse_participants(cls, v):
+        if isinstance(v, str):
+            return json.loads(v) if v else []
+        return v or []
+
+    @validator("categories", pre=True)
+    def parse_categories(cls, v):
+        if isinstance(v, str):
+            return json.loads(v) if v else []
+        return v or []
+
+    @validator("recurrence", pre=True)
+    def parse_recurrence(cls, v):
+        if isinstance(v, str):
+            return json.loads(v) if v else None
+        return v
+
+    @property
+    def address(self) -> str:
+        """NIP-52 replaceable-event address (31922:pubkey:d-tag)."""
+        return f"31922:{self.pubkey}:{self.d_tag}"
+
+
+class PublicTask(BaseModel):
+    """Trimmed task payload for the public/anonymous endpoint."""
+
+    id: str
+    pubkey: str
+    d_tag: str
+    title: str
+    start_date: str
+    end_date: str | None = None
+    description: str = ""
+    location: str | None = None
+    status: str
+    event_type: str
+    participants: list[Participant] = Field(default_factory=list)
+    categories: list[str] = Field(default_factory=list)
+    recurrence: Recurrence | None = None
+
+    @validator("participants", pre=True)
+    def parse_participants(cls, v):
+        if isinstance(v, str):
+            return json.loads(v) if v else []
+        return v or []
+
+    @validator("categories", pre=True)
+    def parse_categories(cls, v):
+        if isinstance(v, str):
+            return json.loads(v) if v else []
+        return v or []
+
+    @validator("recurrence", pre=True)
+    def parse_recurrence(cls, v):
+        if isinstance(v, str):
+            return json.loads(v) if v else None
+        return v
+
+
+class CreateTaskCompletion(BaseModel):
+    task_address: str  # "31922:pubkey:d_tag"
+    task_status: TaskStatus = "claimed"
+    occurrence: str | None = None  # YYYY-MM-DD for recurring tasks
+    completed_at: int | None = None  # unix ts; set when task_status == 'completed'
+    notes: str = ""
+
+
+class TaskCompletion(BaseModel):
+    id: str  # Nostr event id (or local hash for not-yet-published)
+    task_address: str
+    pubkey: str  # claimer
+    occurrence: str | None = None
+    task_status: TaskStatus = "claimed"
+    completed_at: int | None = None
+    notes: str = ""
+    nostr_created_at: int
+    time: datetime
+
+
+class TasksSettings(BaseModel):
+    """Extension-level settings singleton."""
+
+    public_listing: bool = False  # expose /api/v1/tasks/public if enabled