refactor(models): one iso() for every to_dict timestamp; mixins replace hand-rolled created_at/updated_at (#2827, milestone 296 area 3)

Reading all 28 models against each other: 54 `x.isoformat() if x else None` /
`x.isoformat()` expressions in 23 to_dict methods, in two guarded/unguarded
wordings, become iso() from models/base.py — uniform, and a row read before
flush serialises as null instead of raising. Rulebook / RulebookTopic / Rule
carried byte-identical copies of TimestampMixin's two columns;
InvitationToken / PasswordResetToken / NoteUsageEvent carried CreatedAtMixin's —
all six now use the mixin. AppLog and RetrievalLog keep their explicit
created_at, commented: their composite index orders on `created_at.desc()`,
which needs the column object in the class body. Schema-neutral (same column
definitions) — no migration.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

src/scribe/models/api_key.py

@@ -4,7 +4,7 @@ from sqlalchemy import DateTime, ForeignKey, Index, Integer, Text
 from sqlalchemy.orm import Mapped, mapped_column
 
 from scribe.models import Base
-from scribe.models.base import CreatedAtMixin
+from scribe.models.base import CreatedAtMixin, iso
 
 
 class ApiKey(Base, CreatedAtMixin):
@@ -36,7 +36,7 @@ class ApiKey(Base, CreatedAtMixin):
             "name": self.name,
             "key_prefix": self.key_prefix,
             "scope": self.scope,
-            "last_used_at": self.last_used_at.isoformat() if self.last_used_at else None,
-            "created_at": self.created_at.isoformat(),
-            "revoked_at": self.revoked_at.isoformat() if self.revoked_at else None,
+            "last_used_at": iso(self.last_used_at),
+            "created_at": iso(self.created_at),
+            "revoked_at": iso(self.revoked_at),
         }

src/scribe/models/app_log.py

@@ -4,6 +4,7 @@ from sqlalchemy import DateTime, Float, Index, Integer, Text
 from sqlalchemy.orm import Mapped, mapped_column
 
 from scribe.models import Base
+from scribe.models.base import iso
 
 
 class AppLog(Base):
@@ -20,6 +21,9 @@ class AppLog(Base):
     duration_ms: Mapped[float | None] = mapped_column(Float, nullable=True)
     ip_address: Mapped[str | None] = mapped_column(Text, nullable=True)
     details: Mapped[str | None] = mapped_column(Text, nullable=True)
+    # Declared here rather than via CreatedAtMixin on purpose: the composite
+    # index below orders on `created_at.desc()`, which needs the column object
+    # in this class body — a mixin's column is not in scope there.
     created_at: Mapped[datetime] = mapped_column(
         DateTime(timezone=True), default=lambda: datetime.now(timezone.utc)
     )
@@ -44,5 +48,5 @@ class AppLog(Base):
             "duration_ms": self.duration_ms,
             "ip_address": self.ip_address,
             "details": self.details,
-            "created_at": self.created_at.isoformat() if self.created_at else None,
+            "created_at": iso(self.created_at),
         }

src/scribe/models/base.py

@@ -1,9 +1,19 @@
-from datetime import datetime, timezone
+from datetime import date, datetime, timezone
 
 from sqlalchemy import DateTime, Text
 from sqlalchemy.orm import Mapped, mapped_column
 
 
+def iso(value: datetime | date | None) -> str | None:
+    """ISO-8601 for a payload, None for an unset column.
+
+    Every model's to_dict serialises timestamps through this one helper so a
+    row read before flush (created_at still None) and a nullable column both
+    come out as null instead of raising on `.isoformat()`.
+    """
+    return value.isoformat() if value else None
+
+
 class SoftDeleteMixin:
     """Recoverable-delete columns. NULL deleted_at = live row. deleted_batch_id
     groups rows soft-deleted in one operation so a cascade restores as a unit."""

src/scribe/models/code_shape.py

@@ -13,7 +13,7 @@ from sqlalchemy import (
 from sqlalchemy.orm import Mapped, mapped_column
 
 from scribe.models import Base
-from scribe.models.base import TimestampMixin
+from scribe.models.base import TimestampMixin, iso
 
 # The classification vocabulary (note 2786). `unclassified` is the default and
 # THE todo state; every other status is a judgment, stamped with who made it.
@@ -153,18 +153,18 @@ class CodeShape(Base, TimestampMixin):
             "snippet_id": self.snippet_id,
             "reason": self.reason,
             "classified_by": self.classified_by,
-            "classified_at": self.classified_at.isoformat() if self.classified_at else None,
+            "classified_at": iso(self.classified_at),
             "first_seen_commit": self.first_seen_commit,
             "last_seen_commit": self.last_seen_commit,
-            "vanished_at": self.vanished_at.isoformat() if self.vanished_at else None,
+            "vanished_at": iso(self.vanished_at),
             "signature": self.signature,
             "body_sha": self.body_sha,
             "proposal": self.proposal,
             "classified_sha": self.classified_sha,
-            "recheck_at": self.recheck_at.isoformat() if self.recheck_at else None,
+            "recheck_at": iso(self.recheck_at),
             "diverges_from": self.diverges_from,
-            "created_at": self.created_at.isoformat(),
-            "updated_at": self.updated_at.isoformat(),
+            "created_at": iso(self.created_at),
+            "updated_at": iso(self.updated_at),
         }
 
 
@@ -221,5 +221,5 @@ class CodeShapeEvent(Base):
             "classified_by": self.classified_by,
             "reason": self.reason,
             "commit": self.commit,
-            "at": self.at.isoformat(),
+            "at": iso(self.at),
         }

src/scribe/models/design_system.py

@@ -20,7 +20,7 @@ from sqlalchemy.dialects.postgresql import JSONB
 from sqlalchemy.orm import Mapped, mapped_column
 
 from scribe.models import Base
-from scribe.models.base import SoftDeleteMixin, TimestampMixin
+from scribe.models.base import SoftDeleteMixin, TimestampMixin, iso
 
 
 class DesignSystem(Base, TimestampMixin, SoftDeleteMixin):
@@ -56,8 +56,8 @@ class DesignSystem(Base, TimestampMixin, SoftDeleteMixin):
             "description": self.description or "",
             "guidance": self.guidance or "",
             "parent_id": self.parent_id,
-            "created_at": self.created_at.isoformat() if self.created_at else None,
-            "updated_at": self.updated_at.isoformat() if self.updated_at else None,
+            "created_at": iso(self.created_at),
+            "updated_at": iso(self.updated_at),
         }
 
 
@@ -153,6 +153,6 @@ class DesignToken(Base, TimestampMixin, SoftDeleteMixin):
             "rationale": self.rationale,
             "supersedes": self.supersedes or [],
             "order_index": self.order_index,
-            "created_at": self.created_at.isoformat() if self.created_at else None,
-            "updated_at": self.updated_at.isoformat() if self.updated_at else None,
+            "created_at": iso(self.created_at),
+            "updated_at": iso(self.updated_at),
         }

src/scribe/models/forge_connection.py

@@ -2,7 +2,7 @@ from sqlalchemy import ForeignKey, Integer, Text, UniqueConstraint
 from sqlalchemy.orm import Mapped, mapped_column
 
 from scribe.models import Base
-from scribe.models.base import TimestampMixin
+from scribe.models.base import TimestampMixin, iso
 
 
 class ForgeConnection(Base, TimestampMixin):
@@ -40,6 +40,6 @@ class ForgeConnection(Base, TimestampMixin):
             "kind": self.kind,
             "base_url": self.base_url,
             "host": self.host,
-            "created_at": self.created_at.isoformat(),
-            "updated_at": self.updated_at.isoformat(),
+            "created_at": iso(self.created_at),
+            "updated_at": iso(self.updated_at),
         }

src/scribe/models/group.py

@@ -4,7 +4,7 @@ from sqlalchemy import ForeignKey, Integer, Text, UniqueConstraint
 from sqlalchemy.orm import Mapped, mapped_column, relationship
 
 from scribe.models import Base
-from scribe.models.base import CreatedAtMixin, TimestampMixin
+from scribe.models.base import CreatedAtMixin, TimestampMixin, iso
 
 
 class Group(Base, TimestampMixin):
@@ -27,8 +27,8 @@ class Group(Base, TimestampMixin):
             "name": self.name,
             "description": self.description,
             "created_by": self.created_by,
-            "created_at": self.created_at.isoformat(),
-            "updated_at": self.updated_at.isoformat(),
+            "created_at": iso(self.created_at),
+            "updated_at": iso(self.updated_at),
         }
 
 
@@ -53,5 +53,5 @@ class GroupMembership(Base, CreatedAtMixin):
             "group_id": self.group_id,
             "user_id": self.user_id,
             "role": self.role,
-            "created_at": self.created_at.isoformat(),
+            "created_at": iso(self.created_at),
         }

src/scribe/models/invitation.py

@@ -4,9 +4,10 @@ from sqlalchemy import Boolean, DateTime, ForeignKey, Index, Text
 from sqlalchemy.orm import Mapped, mapped_column
 
 from scribe.models import Base
+from scribe.models.base import CreatedAtMixin
 
 
-class InvitationToken(Base):
+class InvitationToken(Base, CreatedAtMixin):
     __tablename__ = "invitation_tokens"
 
     id: Mapped[int] = mapped_column(primary_key=True)
@@ -15,9 +16,6 @@ class InvitationToken(Base):
     invited_by: Mapped[int] = mapped_column(ForeignKey("users.id", ondelete="CASCADE"), nullable=False)
     expires_at: Mapped[datetime] = mapped_column(DateTime(timezone=True), nullable=False)
     used: Mapped[bool] = mapped_column(Boolean, default=False, nullable=False)
-    created_at: Mapped[datetime] = mapped_column(
-        DateTime(timezone=True), default=lambda: datetime.now(timezone.utc)
-    )
 
     __table_args__ = (
         Index("ix_invitation_tokens_token_hash", "token_hash"),

src/scribe/models/milestone.py

@@ -2,7 +2,7 @@ from sqlalchemy import ForeignKey, Integer, Text
 from sqlalchemy.orm import Mapped, mapped_column
 
 from scribe.models import Base
-from scribe.models.base import TimestampMixin, SoftDeleteMixin
+from scribe.models.base import SoftDeleteMixin, TimestampMixin, iso
 
 
 class Milestone(Base, TimestampMixin, SoftDeleteMixin):
@@ -30,6 +30,6 @@ class Milestone(Base, TimestampMixin, SoftDeleteMixin):
             "body": self.body,
             "status": self.status,
             "order_index": self.order_index,
-            "created_at": self.created_at.isoformat(),
-            "updated_at": self.updated_at.isoformat(),
+            "created_at": iso(self.created_at),
+            "updated_at": iso(self.updated_at),
         }

src/scribe/models/note.py

@@ -6,7 +6,7 @@ from sqlalchemy.dialects.postgresql import ARRAY, JSONB
 from sqlalchemy.orm import Mapped, mapped_column
 
 from scribe.models import Base
-from scribe.models.base import TimestampMixin, SoftDeleteMixin
+from scribe.models.base import SoftDeleteMixin, TimestampMixin, iso
 
 
 class TaskStatus(str, enum.Enum):
@@ -105,18 +105,14 @@ class Note(Base, TimestampMixin, SoftDeleteMixin):
             "milestone_id": self.milestone_id,
             "status": self.status,
             "priority": self.priority,
-            "due_date": self.due_date.isoformat() if self.due_date else None,
-            "started_at": self.started_at.isoformat() if self.started_at else None,
-            "completed_at": self.completed_at.isoformat() if self.completed_at else None,
+            "due_date": iso(self.due_date),
+            "started_at": iso(self.started_at),
+            "completed_at": iso(self.completed_at),
             "recurrence_rule": self.recurrence_rule,
-            "recurrence_next_spawn_at": (
-                self.recurrence_next_spawn_at.isoformat()
-                if self.recurrence_next_spawn_at
-                else None
-            ),
+            "recurrence_next_spawn_at": iso(self.recurrence_next_spawn_at),
             "is_task": self.is_task,
             "note_type": self.note_type or "note",
             "task_kind": self.task_kind,
-            "created_at": self.created_at.isoformat(),
-            "updated_at": self.updated_at.isoformat(),
+            "created_at": iso(self.created_at),
+            "updated_at": iso(self.updated_at),
         }

src/scribe/models/note_draft.py

@@ -2,7 +2,7 @@ from sqlalchemy import ForeignKey, Integer, Text
 from sqlalchemy.orm import Mapped, mapped_column
 
 from scribe.models import Base
-from scribe.models.base import TimestampMixin
+from scribe.models.base import TimestampMixin, iso
 
 
 class NoteDraft(Base, TimestampMixin):
@@ -25,6 +25,6 @@ class NoteDraft(Base, TimestampMixin):
             "original_body": self.original_body,
             "instruction": self.instruction,
             "scope": self.scope,
-            "created_at": self.created_at.isoformat(),
-            "updated_at": self.updated_at.isoformat(),
+            "created_at": iso(self.created_at),
+            "updated_at": iso(self.updated_at),
         }

src/scribe/models/note_supersession.py

@@ -2,7 +2,7 @@ from sqlalchemy import ForeignKey, Index, Integer, UniqueConstraint
 from sqlalchemy.orm import Mapped, mapped_column
 
 from scribe.models import Base
-from scribe.models.base import CreatedAtMixin
+from scribe.models.base import CreatedAtMixin, iso
 
 
 class NoteSupersession(Base, CreatedAtMixin):
@@ -66,5 +66,5 @@ class NoteSupersession(Base, CreatedAtMixin):
             "id": self.id,
             "superseder_id": self.superseder_id,
             "superseded_id": self.superseded_id,
-            "created_at": self.created_at.isoformat() if self.created_at else None,
+            "created_at": iso(self.created_at),
         }

src/scribe/models/note_usage.py

@@ -1,15 +1,14 @@
-from datetime import datetime, timezone
-
-from sqlalchemy import DateTime, Index, Integer, Text
+from sqlalchemy import Index, Integer, Text
 from sqlalchemy.orm import Mapped, mapped_column
 
 from scribe.models import Base
+from scribe.models.base import CreatedAtMixin, iso
 
 SURFACED = "surfaced"
 PULLED = "pulled"
 
 
-class NoteUsageEvent(Base):
+class NoteUsageEvent(Base, CreatedAtMixin):
     """One row per time a note was SURFACED to the agent, or PULLED in full.
 
     Answers the question RetrievalLog cannot: not "what did the ranker return
@@ -44,9 +43,6 @@ class NoteUsageEvent(Base):
     __tablename__ = "note_usage_events"
 
     id: Mapped[int] = mapped_column(primary_key=True)
-    created_at: Mapped[datetime] = mapped_column(
-        DateTime(timezone=True), default=lambda: datetime.now(timezone.utc)
-    )
     user_id: Mapped[int | None] = mapped_column(Integer, nullable=True)
     note_id: Mapped[int] = mapped_column(Integer, nullable=False)
     # 'surfaced' | 'pulled'
@@ -81,7 +77,7 @@ class NoteUsageEvent(Base):
     def to_dict(self) -> dict:
         return {
             "id": self.id,
-            "created_at": self.created_at.isoformat() if self.created_at else None,
+            "created_at": iso(self.created_at),
             "user_id": self.user_id,
             "note_id": self.note_id,
             "event": self.event,

src/scribe/models/note_version.py

@@ -2,7 +2,7 @@ from sqlalchemy import ARRAY, ForeignKey, Integer, Text
 from sqlalchemy.orm import Mapped, mapped_column
 
 from scribe.models import Base
-from scribe.models.base import CreatedAtMixin
+from scribe.models.base import CreatedAtMixin, iso
 
 
 class NoteVersion(Base, CreatedAtMixin):
@@ -26,7 +26,7 @@ class NoteVersion(Base, CreatedAtMixin):
             "tags": self.tags or [],
             "pin_kind": self.pin_kind,
             "pin_label": self.pin_label,
-            "created_at": self.created_at.isoformat(),
+            "created_at": iso(self.created_at),
         }
         if include_body:
             d["body"] = self.body

src/scribe/models/notification.py

@@ -5,7 +5,7 @@ from sqlalchemy.dialects.postgresql import JSONB
 from sqlalchemy.orm import Mapped, mapped_column
 
 from scribe.models import Base
-from scribe.models.base import CreatedAtMixin
+from scribe.models.base import CreatedAtMixin, iso
 
 
 class Notification(Base, CreatedAtMixin):
@@ -26,6 +26,6 @@ class Notification(Base, CreatedAtMixin):
             "user_id": self.user_id,
             "type": self.type,
             "payload": self.payload,
-            "read_at": self.read_at.isoformat() if self.read_at else None,
-            "created_at": self.created_at.isoformat(),
+            "read_at": iso(self.read_at),
+            "created_at": iso(self.created_at),
         }

src/scribe/models/password_reset.py

@@ -4,9 +4,10 @@ from sqlalchemy import Boolean, DateTime, ForeignKey, Index, Text
 from sqlalchemy.orm import Mapped, mapped_column
 
 from scribe.models import Base
+from scribe.models.base import CreatedAtMixin
 
 
-class PasswordResetToken(Base):
+class PasswordResetToken(Base, CreatedAtMixin):
     __tablename__ = "password_reset_tokens"
 
     id: Mapped[int] = mapped_column(primary_key=True)
@@ -14,9 +15,6 @@ class PasswordResetToken(Base):
     token_hash: Mapped[str] = mapped_column(Text, nullable=False, unique=True)
     expires_at: Mapped[datetime] = mapped_column(DateTime(timezone=True), nullable=False)
     used: Mapped[bool] = mapped_column(Boolean, default=False, nullable=False)
-    created_at: Mapped[datetime] = mapped_column(
-        DateTime(timezone=True), default=lambda: datetime.now(timezone.utc)
-    )
 
     __table_args__ = (
         Index("ix_password_reset_tokens_token_hash", "token_hash"),

src/scribe/models/project.py

@@ -2,7 +2,7 @@ import enum
 from sqlalchemy import BigInteger, ForeignKey, Integer, Text
 from sqlalchemy.orm import Mapped, mapped_column
 from scribe.models import Base
-from scribe.models.base import TimestampMixin, SoftDeleteMixin
+from scribe.models.base import SoftDeleteMixin, TimestampMixin, iso
 
 
 class ProjectStatus(str, enum.Enum):
@@ -48,6 +48,6 @@ class Project(Base, TimestampMixin, SoftDeleteMixin):
             "color": self.color,
             "design_system_id": self.design_system_id,
             "forge_connection_id": self.forge_connection_id,
-            "created_at": self.created_at.isoformat(),
-            "updated_at": self.updated_at.isoformat(),
+            "created_at": iso(self.created_at),
+            "updated_at": iso(self.updated_at),
         }

src/scribe/models/repo_binding.py

@@ -2,7 +2,7 @@ from sqlalchemy import ForeignKey, Integer, Text, UniqueConstraint
 from sqlalchemy.orm import Mapped, mapped_column
 
 from scribe.models import Base
-from scribe.models.base import TimestampMixin
+from scribe.models.base import TimestampMixin, iso
 
 
 class RepoBinding(Base, TimestampMixin):
@@ -35,6 +35,6 @@ class RepoBinding(Base, TimestampMixin):
             "user_id": self.user_id,
             "project_id": self.project_id,
             "repo_key": self.repo_key,
-            "created_at": self.created_at.isoformat(),
-            "updated_at": self.updated_at.isoformat(),
+            "created_at": iso(self.created_at),
+            "updated_at": iso(self.updated_at),
         }

src/scribe/models/retrieval_log.py

@@ -5,6 +5,7 @@ from sqlalchemy.dialects.postgresql import JSONB
 from sqlalchemy.orm import Mapped, mapped_column
 
 from scribe.models import Base
+from scribe.models.base import iso
 
 
 class RetrievalLog(Base):
@@ -23,6 +24,9 @@ class RetrievalLog(Base):
     __tablename__ = "retrieval_logs"
 
     id: Mapped[int] = mapped_column(primary_key=True)
+    # Declared here rather than via CreatedAtMixin on purpose: the composite
+    # index below orders on `created_at.desc()`, which needs the column object
+    # in this class body — a mixin's column is not in scope there.
     created_at: Mapped[datetime] = mapped_column(
         DateTime(timezone=True), default=lambda: datetime.now(timezone.utc)
     )
@@ -54,7 +58,7 @@ class RetrievalLog(Base):
     def to_dict(self) -> dict:
         return {
             "id": self.id,
-            "created_at": self.created_at.isoformat() if self.created_at else None,
+            "created_at": iso(self.created_at),
             "user_id": self.user_id,
             "source": self.source,
             "query": self.query,

src/scribe/models/rulebook.py

@@ -4,10 +4,10 @@ from sqlalchemy import BigInteger, Boolean, Column, DateTime, ForeignKey, Index,
 from sqlalchemy.orm import Mapped, mapped_column
 
 from scribe.models import Base
-from scribe.models.base import SoftDeleteMixin
+from scribe.models.base import SoftDeleteMixin, TimestampMixin, iso
 
 
-class Rulebook(Base, SoftDeleteMixin):
+class Rulebook(Base, TimestampMixin, SoftDeleteMixin):
     __tablename__ = "rulebooks"
 
     id: Mapped[int] = mapped_column(BigInteger, primary_key=True)
@@ -19,14 +19,6 @@ class Rulebook(Base, SoftDeleteMixin):
     always_on: Mapped[bool] = mapped_column(
         Boolean, default=False, nullable=False, server_default="false"
     )
-    created_at: Mapped[datetime] = mapped_column(
-        DateTime(timezone=True), default=lambda: datetime.now(timezone.utc)
-    )
-    updated_at: Mapped[datetime] = mapped_column(
-        DateTime(timezone=True),
-        default=lambda: datetime.now(timezone.utc),
-        onupdate=lambda: datetime.now(timezone.utc),
-    )
 
     def to_dict(self) -> dict:
         return {
@@ -35,12 +27,12 @@ class Rulebook(Base, SoftDeleteMixin):
             "title": self.title,
             "description": self.description or "",
             "always_on": self.always_on,
-            "created_at": self.created_at.isoformat() if self.created_at else None,
-            "updated_at": self.updated_at.isoformat() if self.updated_at else None,
+            "created_at": iso(self.created_at),
+            "updated_at": iso(self.updated_at),
         }
 
 
-class RulebookTopic(Base, SoftDeleteMixin):
+class RulebookTopic(Base, TimestampMixin, SoftDeleteMixin):
     __tablename__ = "rulebook_topics"
     # Partial unique: a title is unique among LIVE topics in a rulebook, so a
     # trashed topic doesn't block recreating/restoring the same title.
@@ -58,14 +50,6 @@ class RulebookTopic(Base, SoftDeleteMixin):
     title: Mapped[str] = mapped_column(Text)
     description: Mapped[str | None] = mapped_column(Text, nullable=True)
     order_index: Mapped[int] = mapped_column(Integer, default=0)
-    created_at: Mapped[datetime] = mapped_column(
-        DateTime(timezone=True), default=lambda: datetime.now(timezone.utc)
-    )
-    updated_at: Mapped[datetime] = mapped_column(
-        DateTime(timezone=True),
-        default=lambda: datetime.now(timezone.utc),
-        onupdate=lambda: datetime.now(timezone.utc),
-    )
 
     def to_dict(self) -> dict:
         return {
@@ -74,12 +58,12 @@ class RulebookTopic(Base, SoftDeleteMixin):
             "title": self.title,
             "description": self.description or "",
             "order_index": self.order_index,
-            "created_at": self.created_at.isoformat() if self.created_at else None,
-            "updated_at": self.updated_at.isoformat() if self.updated_at else None,
+            "created_at": iso(self.created_at),
+            "updated_at": iso(self.updated_at),
         }
 
 
-class Rule(Base, SoftDeleteMixin):
+class Rule(Base, TimestampMixin, SoftDeleteMixin):
     __tablename__ = "rules"
     # Partial unique: title unique among LIVE rules in a topic (soft-deleted
     # rules don't block recreating/restoring the same title).
@@ -109,14 +93,6 @@ class Rule(Base, SoftDeleteMixin):
     why: Mapped[str | None] = mapped_column(Text, nullable=True)
     how_to_apply: Mapped[str | None] = mapped_column(Text, nullable=True)
     order_index: Mapped[int] = mapped_column(Integer, default=0)
-    created_at: Mapped[datetime] = mapped_column(
-        DateTime(timezone=True), default=lambda: datetime.now(timezone.utc)
-    )
-    updated_at: Mapped[datetime] = mapped_column(
-        DateTime(timezone=True),
-        default=lambda: datetime.now(timezone.utc),
-        onupdate=lambda: datetime.now(timezone.utc),
-    )
 
     def to_dict(self) -> dict:
         return {
@@ -128,8 +104,8 @@ class Rule(Base, SoftDeleteMixin):
             "why": self.why or "",
             "how_to_apply": self.how_to_apply or "",
             "order_index": self.order_index,
-            "created_at": self.created_at.isoformat() if self.created_at else None,
-            "updated_at": self.updated_at.isoformat() if self.updated_at else None,
+            "created_at": iso(self.created_at),
+            "updated_at": iso(self.updated_at),
         }
 
 

src/scribe/models/share.py

@@ -2,7 +2,7 @@ from sqlalchemy import CheckConstraint, ForeignKey, Integer, Text
 from sqlalchemy.orm import Mapped, mapped_column
 
 from scribe.models import Base
-from scribe.models.base import TimestampMixin
+from scribe.models.base import TimestampMixin, iso
 
 
 class ProjectShare(Base, TimestampMixin):
@@ -37,8 +37,8 @@ class ProjectShare(Base, TimestampMixin):
             "shared_with_group_id": self.shared_with_group_id,
             "permission": self.permission,
             "invited_by": self.invited_by,
-            "created_at": self.created_at.isoformat(),
-            "updated_at": self.updated_at.isoformat(),
+            "created_at": iso(self.created_at),
+            "updated_at": iso(self.updated_at),
         }
 
 
@@ -74,6 +74,6 @@ class NoteShare(Base, TimestampMixin):
             "shared_with_group_id": self.shared_with_group_id,
             "permission": self.permission,
             "invited_by": self.invited_by,
-            "created_at": self.created_at.isoformat(),
-            "updated_at": self.updated_at.isoformat(),
+            "created_at": iso(self.created_at),
+            "updated_at": iso(self.updated_at),
         }

src/scribe/models/system.py

@@ -2,7 +2,7 @@ from sqlalchemy import ForeignKey, Index, Integer, Text, UniqueConstraint
 from sqlalchemy.orm import Mapped, mapped_column
 
 from scribe.models import Base
-from scribe.models.base import CreatedAtMixin, TimestampMixin, SoftDeleteMixin
+from scribe.models.base import CreatedAtMixin, SoftDeleteMixin, TimestampMixin, iso
 
 
 class System(Base, TimestampMixin, SoftDeleteMixin):
@@ -44,8 +44,8 @@ class System(Base, TimestampMixin, SoftDeleteMixin):
             "color": self.color,
             "status": self.status,
             "order_index": self.order_index,
-            "created_at": self.created_at.isoformat(),
-            "updated_at": self.updated_at.isoformat(),
+            "created_at": iso(self.created_at),
+            "updated_at": iso(self.updated_at),
         }
 
 

src/scribe/models/task_log.py

@@ -2,7 +2,7 @@ from sqlalchemy import ForeignKey, Integer, Text
 from sqlalchemy.orm import Mapped, mapped_column
 
 from scribe.models import Base
-from scribe.models.base import TimestampMixin
+from scribe.models.base import TimestampMixin, iso
 
 
 class TaskLog(Base, TimestampMixin):
@@ -21,6 +21,6 @@ class TaskLog(Base, TimestampMixin):
             "user_id": self.user_id,
             "content": self.content,
             "duration_minutes": self.duration_minutes,
-            "created_at": self.created_at.isoformat(),
-            "updated_at": self.updated_at.isoformat(),
+            "created_at": iso(self.created_at),
+            "updated_at": iso(self.updated_at),
         }

src/scribe/models/user.py

@@ -2,7 +2,7 @@ from sqlalchemy import Index, Integer, Text
 from sqlalchemy.orm import Mapped, mapped_column
 
 from scribe.models import Base
-from scribe.models.base import CreatedAtMixin
+from scribe.models.base import CreatedAtMixin, iso
 
 
 class User(Base, CreatedAtMixin):
@@ -26,6 +26,6 @@ class User(Base, CreatedAtMixin):
             "username": self.username,
             "email": self.email,
             "role": self.role,
-            "created_at": self.created_at.isoformat(),
+            "created_at": iso(self.created_at),
             "has_password": self.password_hash is not None,
         }