From 45bc5bf8f6ec1298c5ff94f6c70bdf64af59d5bc Mon Sep 17 00:00:00 2001
From: Ian Roddis <31021769+iroddis@users.noreply.github.com>
Date: Thu, 25 Jun 2026 11:25:26 -0300
Subject: [PATCH] Adding audit log

---
 .../fd5379986da4_add_audit_logs_table.py      |  29 ++
 app/api/audit_log.py                          |  19 ++
 app/api/iso_threads.py                        |  30 ++-
 app/api/manufacturers.py                      |  29 +-
 app/api/part_types.py                         |  30 ++-
 app/api/roles.py                              |  30 ++-
 app/api/router.py                             |   3 +-
 app/api/scope_models.py                       |  29 +-
 app/api/unc_threads.py                        |  30 ++-
 app/api/users.py                              |  46 +++-
 app/crud/audit.py                             |  48 ++++
 app/models/__init__.py                        |   2 +
 app/models/audit_log.py                       |  23 ++
 app/schemas/audit_log.py                      |  16 ++
 app/templates/_nav.html                       |   3 +
 app/templates/admin/audit_log.html            |  37 +++
 app/web/admin.py                              | 255 +++++++++++++-----
 scripts/seed.py                               |   3 +-
 18 files changed, 543 insertions(+), 119 deletions(-)
 create mode 100644 alembic/versions/fd5379986da4_add_audit_logs_table.py
 create mode 100644 app/api/audit_log.py
 create mode 100644 app/crud/audit.py
 create mode 100644 app/models/audit_log.py
 create mode 100644 app/schemas/audit_log.py
 create mode 100644 app/templates/admin/audit_log.html

diff --git a/alembic/versions/fd5379986da4_add_audit_logs_table.py b/alembic/versions/fd5379986da4_add_audit_logs_table.py
new file mode 100644
index 0000000..b891ef2
--- /dev/null
+++ b/alembic/versions/fd5379986da4_add_audit_logs_table.py
@@ -0,0 +1,29 @@
+"""add_audit_logs_table
+
+Revision ID: fd5379986da4
+Revises: e23aa8dd2536
+Create Date: 2026-06-25 11:06:13.028067
+"""
+from typing import Sequence, Union
+
+from alembic import op
+import sqlalchemy as sa
+
+
+# revision identifiers, used by Alembic.
+revision: str = 'fd5379986da4'
+down_revision: Union[str, None] = 'e23aa8dd2536'
+branch_labels: Union[str, Sequence[str], None] = None
+depends_on: Union[str, Sequence[str], None] = None
+
+
+def upgrade() -> None:
+    # ### commands auto generated by Alembic - please adjust! ###
+    pass
+    # ### end Alembic commands ###
+
+
+def downgrade() -> None:
+    # ### commands auto generated by Alembic - please adjust! ###
+    pass
+    # ### end Alembic commands ###
diff --git a/app/api/audit_log.py b/app/api/audit_log.py
new file mode 100644
index 0000000..477801d
--- /dev/null
+++ b/app/api/audit_log.py
@@ -0,0 +1,19 @@
+from fastapi import APIRouter, Depends
+from sqlalchemy.ext.asyncio import AsyncSession
+
+from app.core.database import get_db
+from app.crud import audit as audit_crud
+from app.deps import require_permission
+from app.models.user import User
+from app.schemas.audit_log import AuditLogRead
+
+router = APIRouter()
+
+
+@router.get("", response_model=list[AuditLogRead])
+async def list_audit_log(
+    limit: int = 200,
+    db: AsyncSession = Depends(get_db),
+    _: User = Depends(require_permission("audit_log:read")),
+):
+    return await audit_crud.list_recent(db, limit=limit)
diff --git a/app/api/iso_threads.py b/app/api/iso_threads.py
index f0f1c6e..acc5b12 100644
--- a/app/api/iso_threads.py
+++ b/app/api/iso_threads.py
@@ -2,6 +2,7 @@ from fastapi import APIRouter, Depends, HTTPException, status
 from sqlalchemy.ext.asyncio import AsyncSession
 
 from app.core.database import get_db
+from app.crud import audit as audit_crud
 from app.crud import iso_thread as iso_thread_crud
 from app.deps import require_permission
 from app.models.user import User
@@ -24,14 +25,20 @@ async def list_iso_threads(
 async def create_iso_thread(
     payload: IsoThreadCreate,
     db: AsyncSession = Depends(get_db),
-    _: User = Depends(require_permission("iso_threads:write")),
+    actor: User = Depends(require_permission("iso_threads:write")),
 ):
-    return await iso_thread_crud.create(
+    thread = await iso_thread_crud.create(
         db,
         diameter_mm=payload.diameter_mm,
         pitch_mm=payload.pitch_mm,
         depth_mm=payload.depth_mm,
     )
+    await audit_crud.log(
+        db, actor=actor, action="create", resource_type="IsoThread",
+        resource_id=thread.id,
+        description=audit_crud.describe_create("IsoThread", thread.id, f"M{thread.diameter_mm}×{thread.pitch_mm}"),
+    )
+    return thread
 
 
 @router.get("/{iso_thread_id}", response_model=IsoThreadRead)
@@ -51,21 +58,34 @@ async def update_iso_thread(
     iso_thread_id: int,
     payload: IsoThreadUpdate,
     db: AsyncSession = Depends(get_db),
-    _: User = Depends(require_permission("iso_threads:write")),
+    actor: User = Depends(require_permission("iso_threads:write")),
 ):
     thread = await iso_thread_crud.get(db, iso_thread_id)
     if thread is None:
         raise HTTPException(status_code=status.HTTP_404_NOT_FOUND, detail="ISO thread not found")
-    return await iso_thread_crud.update(db, thread, payload.model_dump(exclude_unset=True))
+    changes = payload.model_dump(exclude_unset=True)
+    thread = await iso_thread_crud.update(db, thread, changes)
+    await audit_crud.log(
+        db, actor=actor, action="update", resource_type="IsoThread",
+        resource_id=thread.id,
+        description=audit_crud.describe_update("IsoThread", thread.id, changes),
+    )
+    return thread
 
 
 @router.delete("/{iso_thread_id}", status_code=status.HTTP_204_NO_CONTENT)
 async def delete_iso_thread(
     iso_thread_id: int,
     db: AsyncSession = Depends(get_db),
-    _: User = Depends(require_permission("iso_threads:delete")),
+    actor: User = Depends(require_permission("iso_threads:delete")),
 ):
     thread = await iso_thread_crud.get(db, iso_thread_id)
     if thread is None:
         raise HTTPException(status_code=status.HTTP_404_NOT_FOUND, detail="ISO thread not found")
+    name = f"M{thread.diameter_mm}×{thread.pitch_mm}"
     await iso_thread_crud.delete(db, thread)
+    await audit_crud.log(
+        db, actor=actor, action="delete", resource_type="IsoThread",
+        resource_id=iso_thread_id,
+        description=audit_crud.describe_delete("IsoThread", iso_thread_id, name),
+    )
diff --git a/app/api/manufacturers.py b/app/api/manufacturers.py
index 1781a86..0013a3e 100644
--- a/app/api/manufacturers.py
+++ b/app/api/manufacturers.py
@@ -2,6 +2,7 @@ from fastapi import APIRouter, Depends, HTTPException, status
 from sqlalchemy.ext.asyncio import AsyncSession
 
 from app.core.database import get_db
+from app.crud import audit as audit_crud
 from app.crud import manufacturer as manufacturer_crud
 from app.deps import require_permission
 from app.models.user import User
@@ -24,14 +25,20 @@ async def list_manufacturers(
 async def create_manufacturer(
     payload: ManufacturerCreate,
     db: AsyncSession = Depends(get_db),
-    _: User = Depends(require_permission("manufacturers:write")),
+    actor: User = Depends(require_permission("manufacturers:write")),
 ):
-    return await manufacturer_crud.create(
+    m = await manufacturer_crud.create(
         db,
         name=payload.name,
         url=str(payload.url),
         logo_url=str(payload.logo_url) if payload.logo_url else None,
     )
+    await audit_crud.log(
+        db, actor=actor, action="create", resource_type="Manufacturer",
+        resource_id=m.id,
+        description=audit_crud.describe_create("Manufacturer", m.id, m.name),
+    )
+    return m
 
 
 @router.get("/{manufacturer_id}", response_model=ManufacturerRead)
@@ -51,7 +58,7 @@ async def update_manufacturer(
     manufacturer_id: int,
     payload: ManufacturerUpdate,
     db: AsyncSession = Depends(get_db),
-    _: User = Depends(require_permission("manufacturers:write")),
+    actor: User = Depends(require_permission("manufacturers:write")),
 ):
     m = await manufacturer_crud.get(db, manufacturer_id)
     if m is None:
@@ -61,16 +68,28 @@ async def update_manufacturer(
         data["url"] = str(data["url"])
     if "logo_url" in data and data["logo_url"] is not None:
         data["logo_url"] = str(data["logo_url"])
-    return await manufacturer_crud.update(db, m, data)
+    m = await manufacturer_crud.update(db, m, data)
+    await audit_crud.log(
+        db, actor=actor, action="update", resource_type="Manufacturer",
+        resource_id=m.id,
+        description=audit_crud.describe_update("Manufacturer", m.id, data),
+    )
+    return m
 
 
 @router.delete("/{manufacturer_id}", status_code=status.HTTP_204_NO_CONTENT)
 async def delete_manufacturer(
     manufacturer_id: int,
     db: AsyncSession = Depends(get_db),
-    _: User = Depends(require_permission("manufacturers:delete")),
+    actor: User = Depends(require_permission("manufacturers:delete")),
 ):
     m = await manufacturer_crud.get(db, manufacturer_id)
     if m is None:
         raise HTTPException(status_code=status.HTTP_404_NOT_FOUND, detail="Manufacturer not found")
+    name = m.name
     await manufacturer_crud.delete(db, m)
+    await audit_crud.log(
+        db, actor=actor, action="delete", resource_type="Manufacturer",
+        resource_id=manufacturer_id,
+        description=audit_crud.describe_delete("Manufacturer", manufacturer_id, name),
+    )
diff --git a/app/api/part_types.py b/app/api/part_types.py
index b1024b8..2e41e92 100644
--- a/app/api/part_types.py
+++ b/app/api/part_types.py
@@ -2,6 +2,7 @@ from fastapi import APIRouter, Depends, HTTPException, status
 from sqlalchemy.ext.asyncio import AsyncSession
 
 from app.core.database import get_db
+from app.crud import audit as audit_crud
 from app.crud import part_type as part_type_crud
 from app.deps import require_permission
 from app.models.user import User
@@ -24,9 +25,15 @@ async def list_part_types(
 async def create_part_type(
     payload: PartTypeCreate,
     db: AsyncSession = Depends(get_db),
-    _: User = Depends(require_permission("part_types:write")),
+    actor: User = Depends(require_permission("part_types:write")),
 ):
-    return await part_type_crud.create(db, name=payload.name)
+    pt = await part_type_crud.create(db, name=payload.name)
+    await audit_crud.log(
+        db, actor=actor, action="create", resource_type="PartType",
+        resource_id=pt.id,
+        description=audit_crud.describe_create("PartType", pt.id, pt.name),
+    )
+    return pt
 
 
 @router.get("/{part_type_id}", response_model=PartTypeRead)
@@ -46,21 +53,34 @@ async def update_part_type(
     part_type_id: int,
     payload: PartTypeUpdate,
     db: AsyncSession = Depends(get_db),
-    _: User = Depends(require_permission("part_types:write")),
+    actor: User = Depends(require_permission("part_types:write")),
 ):
     pt = await part_type_crud.get(db, part_type_id)
     if pt is None:
         raise HTTPException(status_code=status.HTTP_404_NOT_FOUND, detail="Part type not found")
-    return await part_type_crud.update(db, pt, payload.model_dump(exclude_unset=True))
+    changes = payload.model_dump(exclude_unset=True)
+    pt = await part_type_crud.update(db, pt, changes)
+    await audit_crud.log(
+        db, actor=actor, action="update", resource_type="PartType",
+        resource_id=pt.id,
+        description=audit_crud.describe_update("PartType", pt.id, changes),
+    )
+    return pt
 
 
 @router.delete("/{part_type_id}", status_code=status.HTTP_204_NO_CONTENT)
 async def delete_part_type(
     part_type_id: int,
     db: AsyncSession = Depends(get_db),
-    _: User = Depends(require_permission("part_types:delete")),
+    actor: User = Depends(require_permission("part_types:delete")),
 ):
     pt = await part_type_crud.get(db, part_type_id)
     if pt is None:
         raise HTTPException(status_code=status.HTTP_404_NOT_FOUND, detail="Part type not found")
+    name = pt.name
     await part_type_crud.delete(db, pt)
+    await audit_crud.log(
+        db, actor=actor, action="delete", resource_type="PartType",
+        resource_id=part_type_id,
+        description=audit_crud.describe_delete("PartType", part_type_id, name),
+    )
diff --git a/app/api/roles.py b/app/api/roles.py
index 1410b74..b37be45 100644
--- a/app/api/roles.py
+++ b/app/api/roles.py
@@ -2,6 +2,7 @@ from fastapi import APIRouter, Depends, HTTPException, status
 from sqlalchemy.ext.asyncio import AsyncSession
 
 from app.core.database import get_db
+from app.crud import audit as audit_crud
 from app.crud import role as role_crud
 from app.deps import require_permission
 from app.models.user import User
@@ -22,18 +23,24 @@ async def list_roles(
 async def create_role(
     payload: RoleCreate,
     db: AsyncSession = Depends(get_db),
-    _: User = Depends(require_permission("roles:write")),
+    actor: User = Depends(require_permission("roles:write")),
 ):
     if await role_crud.get_by_name(db, payload.name):
         raise HTTPException(
             status_code=status.HTTP_409_CONFLICT, detail="Role already exists"
         )
-    return await role_crud.create(
+    role = await role_crud.create(
         db,
         name=payload.name,
         description=payload.description,
         permission_ids=payload.permission_ids,
     )
+    await audit_crud.log(
+        db, actor=actor, action="create", resource_type="Role",
+        resource_id=role.id,
+        description=audit_crud.describe_create("Role", role.id, role.name),
+    )
+    return role
 
 
 @router.get("/permissions", response_model=list[PermissionRead])
@@ -63,25 +70,38 @@ async def update_role(
     role_id: int,
     payload: RoleUpdate,
     db: AsyncSession = Depends(get_db),
-    _: User = Depends(require_permission("roles:write")),
+    actor: User = Depends(require_permission("roles:write")),
 ):
     role = await role_crud.get(db, role_id)
     if role is None:
         raise HTTPException(
             status_code=status.HTTP_404_NOT_FOUND, detail="Role not found"
         )
-    return await role_crud.update(db, role, payload.model_dump(exclude_unset=True))
+    changes = payload.model_dump(exclude_unset=True)
+    role = await role_crud.update(db, role, changes)
+    await audit_crud.log(
+        db, actor=actor, action="update", resource_type="Role",
+        resource_id=role.id,
+        description=audit_crud.describe_update("Role", role.id, changes),
+    )
+    return role
 
 
 @router.delete("/{role_id}", status_code=status.HTTP_204_NO_CONTENT)
 async def delete_role(
     role_id: int,
     db: AsyncSession = Depends(get_db),
-    _: User = Depends(require_permission("roles:write")),
+    actor: User = Depends(require_permission("roles:write")),
 ):
     role = await role_crud.get(db, role_id)
     if role is None:
         raise HTTPException(
             status_code=status.HTTP_404_NOT_FOUND, detail="Role not found"
         )
+    name = role.name
     await role_crud.delete(db, role)
+    await audit_crud.log(
+        db, actor=actor, action="delete", resource_type="Role",
+        resource_id=role_id,
+        description=audit_crud.describe_delete("Role", role_id, name),
+    )
diff --git a/app/api/router.py b/app/api/router.py
index c6c7a02..0b914e1 100644
--- a/app/api/router.py
+++ b/app/api/router.py
@@ -1,6 +1,6 @@
 from fastapi import APIRouter
 
-from app.api import auth, iso_threads, manufacturers, part_types, roles, scope_models, unc_threads, users
+from app.api import audit_log, auth, iso_threads, manufacturers, part_types, roles, scope_models, unc_threads, users
 
 api_router = APIRouter()
 api_router.include_router(auth.router, prefix="/auth", tags=["auth"])
@@ -11,3 +11,4 @@ api_router.include_router(unc_threads.router, prefix="/unc-threads", tags=["unc-
 api_router.include_router(manufacturers.router, prefix="/manufacturers", tags=["manufacturers"])
 api_router.include_router(scope_models.router, prefix="/scope-models", tags=["scope-models"])
 api_router.include_router(part_types.router, prefix="/part-types", tags=["part-types"])
+api_router.include_router(audit_log.router, prefix="/audit-log", tags=["audit-log"])
diff --git a/app/api/scope_models.py b/app/api/scope_models.py
index f7d6f9b..239953c 100644
--- a/app/api/scope_models.py
+++ b/app/api/scope_models.py
@@ -2,6 +2,7 @@ from fastapi import APIRouter, Depends, HTTPException, status
 from sqlalchemy.ext.asyncio import AsyncSession
 
 from app.core.database import get_db
+from app.crud import audit as audit_crud
 from app.crud import scope_model as scope_model_crud
 from app.deps import require_permission
 from app.models.user import User
@@ -24,14 +25,20 @@ async def list_scope_models(
 async def create_scope_model(
     payload: ScopeModelCreate,
     db: AsyncSession = Depends(get_db),
-    _: User = Depends(require_permission("scope_models:write")),
+    actor: User = Depends(require_permission("scope_models:write")),
 ):
-    return await scope_model_crud.create(
+    sm = await scope_model_crud.create(
         db,
         name=payload.name,
         manufacturer_id=payload.manufacturer_id,
         url=str(payload.url) if payload.url else None,
     )
+    await audit_crud.log(
+        db, actor=actor, action="create", resource_type="ScopeModel",
+        resource_id=sm.id,
+        description=audit_crud.describe_create("ScopeModel", sm.id, sm.name),
+    )
+    return sm
 
 
 @router.get("/{scope_model_id}", response_model=ScopeModelRead)
@@ -51,7 +58,7 @@ async def update_scope_model(
     scope_model_id: int,
     payload: ScopeModelUpdate,
     db: AsyncSession = Depends(get_db),
-    _: User = Depends(require_permission("scope_models:write")),
+    actor: User = Depends(require_permission("scope_models:write")),
 ):
     sm = await scope_model_crud.get(db, scope_model_id)
     if sm is None:
@@ -59,16 +66,28 @@ async def update_scope_model(
     data = payload.model_dump(exclude_unset=True)
     if "url" in data and data["url"] is not None:
         data["url"] = str(data["url"])
-    return await scope_model_crud.update(db, sm, data)
+    sm = await scope_model_crud.update(db, sm, data)
+    await audit_crud.log(
+        db, actor=actor, action="update", resource_type="ScopeModel",
+        resource_id=sm.id,
+        description=audit_crud.describe_update("ScopeModel", sm.id, data),
+    )
+    return sm
 
 
 @router.delete("/{scope_model_id}", status_code=status.HTTP_204_NO_CONTENT)
 async def delete_scope_model(
     scope_model_id: int,
     db: AsyncSession = Depends(get_db),
-    _: User = Depends(require_permission("scope_models:delete")),
+    actor: User = Depends(require_permission("scope_models:delete")),
 ):
     sm = await scope_model_crud.get(db, scope_model_id)
     if sm is None:
         raise HTTPException(status_code=status.HTTP_404_NOT_FOUND, detail="Scope model not found")
+    name = sm.name
     await scope_model_crud.delete(db, sm)
+    await audit_crud.log(
+        db, actor=actor, action="delete", resource_type="ScopeModel",
+        resource_id=scope_model_id,
+        description=audit_crud.describe_delete("ScopeModel", scope_model_id, name),
+    )
diff --git a/app/api/unc_threads.py b/app/api/unc_threads.py
index f0d32ce..7b52203 100644
--- a/app/api/unc_threads.py
+++ b/app/api/unc_threads.py
@@ -2,6 +2,7 @@ from fastapi import APIRouter, Depends, HTTPException, status
 from sqlalchemy.ext.asyncio import AsyncSession
 
 from app.core.database import get_db
+from app.crud import audit as audit_crud
 from app.crud import unc_thread as unc_thread_crud
 from app.deps import require_permission
 from app.models.user import User
@@ -24,15 +25,21 @@ async def list_unc_threads(
 async def create_unc_thread(
     payload: UncThreadCreate,
     db: AsyncSession = Depends(get_db),
-    _: User = Depends(require_permission("unc_threads:write")),
+    actor: User = Depends(require_permission("unc_threads:write")),
 ):
-    return await unc_thread_crud.create(
+    thread = await unc_thread_crud.create(
         db,
         diameter_fraction=payload.diameter_fraction,
         tpi=payload.tpi,
         series=payload.series,
         depth_in=payload.depth_in,
     )
+    await audit_crud.log(
+        db, actor=actor, action="create", resource_type="UncThread",
+        resource_id=thread.id,
+        description=audit_crud.describe_create("UncThread", thread.id, f"{thread.diameter_fraction}-{thread.tpi} {thread.series.value}"),
+    )
+    return thread
 
 
 @router.get("/{unc_thread_id}", response_model=UncThreadRead)
@@ -52,21 +59,34 @@ async def update_unc_thread(
     unc_thread_id: int,
     payload: UncThreadUpdate,
     db: AsyncSession = Depends(get_db),
-    _: User = Depends(require_permission("unc_threads:write")),
+    actor: User = Depends(require_permission("unc_threads:write")),
 ):
     thread = await unc_thread_crud.get(db, unc_thread_id)
     if thread is None:
         raise HTTPException(status_code=status.HTTP_404_NOT_FOUND, detail="UNC thread not found")
-    return await unc_thread_crud.update(db, thread, payload.model_dump(exclude_unset=True))
+    changes = payload.model_dump(exclude_unset=True)
+    thread = await unc_thread_crud.update(db, thread, changes)
+    await audit_crud.log(
+        db, actor=actor, action="update", resource_type="UncThread",
+        resource_id=thread.id,
+        description=audit_crud.describe_update("UncThread", thread.id, changes),
+    )
+    return thread
 
 
 @router.delete("/{unc_thread_id}", status_code=status.HTTP_204_NO_CONTENT)
 async def delete_unc_thread(
     unc_thread_id: int,
     db: AsyncSession = Depends(get_db),
-    _: User = Depends(require_permission("unc_threads:delete")),
+    actor: User = Depends(require_permission("unc_threads:delete")),
 ):
     thread = await unc_thread_crud.get(db, unc_thread_id)
     if thread is None:
         raise HTTPException(status_code=status.HTTP_404_NOT_FOUND, detail="UNC thread not found")
+    name = f"{thread.diameter_fraction}-{thread.tpi} {thread.series.value}"
     await unc_thread_crud.delete(db, thread)
+    await audit_crud.log(
+        db, actor=actor, action="delete", resource_type="UncThread",
+        resource_id=unc_thread_id,
+        description=audit_crud.describe_delete("UncThread", unc_thread_id, name),
+    )
diff --git a/app/api/users.py b/app/api/users.py
index 57b0500..1b48b71 100644
--- a/app/api/users.py
+++ b/app/api/users.py
@@ -2,6 +2,7 @@ from fastapi import APIRouter, Depends, HTTPException, status
 from sqlalchemy.ext.asyncio import AsyncSession
 
 from app.core.database import get_db
+from app.crud import audit as audit_crud
 from app.crud import user as user_crud
 from app.deps import get_current_user, require_permission
 from app.models.user import User
@@ -29,13 +30,13 @@ async def list_users(
 async def create_user(
     payload: UserCreate,
     db: AsyncSession = Depends(get_db),
-    _: User = Depends(require_permission("users:write")),
+    actor: User = Depends(require_permission("users:write")),
 ):
     if await user_crud.get_by_email(db, payload.email):
         raise HTTPException(
             status_code=status.HTTP_409_CONFLICT, detail="Email already registered"
         )
-    return await user_crud.create(
+    created = await user_crud.create(
         db,
         email=payload.email,
         password=payload.password,
@@ -43,6 +44,12 @@ async def create_user(
         is_superuser=payload.is_superuser,
         role_ids=payload.role_ids,
     )
+    await audit_crud.log(
+        db, actor=actor, action="create", resource_type="User",
+        resource_id=created.id,
+        description=audit_crud.describe_create("User", created.id, created.email),
+    )
+    return created
 
 
 @router.get("/{user_id}", response_model=UserRead)
@@ -51,12 +58,12 @@ async def get_user(
     db: AsyncSession = Depends(get_db),
     _: User = Depends(require_permission("users:read")),
 ):
-    user = await user_crud.get(db, user_id)
-    if user is None:
+    target = await user_crud.get(db, user_id)
+    if target is None:
         raise HTTPException(
             status_code=status.HTTP_404_NOT_FOUND, detail="User not found"
         )
-    return user
+    return target
 
 
 @router.patch("/{user_id}", response_model=UserRead)
@@ -64,25 +71,38 @@ async def update_user(
     user_id: int,
     payload: UserUpdate,
     db: AsyncSession = Depends(get_db),
-    _: User = Depends(require_permission("users:write")),
+    actor: User = Depends(require_permission("users:write")),
 ):
-    user = await user_crud.get(db, user_id)
-    if user is None:
+    target = await user_crud.get(db, user_id)
+    if target is None:
         raise HTTPException(
             status_code=status.HTTP_404_NOT_FOUND, detail="User not found"
         )
-    return await user_crud.update(db, user, payload.model_dump(exclude_unset=True))
+    changes = payload.model_dump(exclude_unset=True)
+    target = await user_crud.update(db, target, changes)
+    await audit_crud.log(
+        db, actor=actor, action="update", resource_type="User",
+        resource_id=user_id,
+        description=audit_crud.describe_update("User", user_id, changes),
+    )
+    return target
 
 
 @router.delete("/{user_id}", status_code=status.HTTP_204_NO_CONTENT)
 async def delete_user(
     user_id: int,
     db: AsyncSession = Depends(get_db),
-    _: User = Depends(require_permission("users:delete")),
+    actor: User = Depends(require_permission("users:delete")),
 ):
-    user = await user_crud.get(db, user_id)
-    if user is None:
+    target = await user_crud.get(db, user_id)
+    if target is None:
         raise HTTPException(
             status_code=status.HTTP_404_NOT_FOUND, detail="User not found"
         )
-    await user_crud.delete(db, user)
+    email = target.email
+    await user_crud.delete(db, target)
+    await audit_crud.log(
+        db, actor=actor, action="delete", resource_type="User",
+        resource_id=user_id,
+        description=audit_crud.describe_delete("User", user_id, email),
+    )
diff --git a/app/crud/audit.py b/app/crud/audit.py
new file mode 100644
index 0000000..b072d4f
--- /dev/null
+++ b/app/crud/audit.py
@@ -0,0 +1,48 @@
+from sqlalchemy import select
+from sqlalchemy.ext.asyncio import AsyncSession
+
+from app.models.audit_log import AuditLog
+from app.models.user import User
+
+
+def describe_create(resource_type: str, resource_id: int, name: str) -> str:
+    return f"Created {resource_type} '{name}' (#{resource_id})"
+
+
+def describe_update(resource_type: str, resource_id: int, changes: dict) -> str:
+    safe = {k: ("***" if k == "password" else v) for k, v in changes.items()}
+    parts = ", ".join(f"{k}={v!r}" for k, v in safe.items())
+    suffix = f": {parts}" if parts else ""
+    return f"Updated {resource_type} #{resource_id}{suffix}"
+
+
+def describe_delete(resource_type: str, resource_id: int, name: str) -> str:
+    return f"Deleted {resource_type} '{name}' (#{resource_id})"
+
+
+async def log(
+    db: AsyncSession,
+    *,
+    actor: User,
+    action: str,
+    resource_type: str,
+    resource_id: int | None,
+    description: str,
+) -> None:
+    entry = AuditLog(
+        user_id=actor.id,
+        user_email=actor.email,
+        action=action,
+        resource_type=resource_type,
+        resource_id=resource_id,
+        description=description,
+    )
+    db.add(entry)
+    await db.commit()
+
+
+async def list_recent(db: AsyncSession, limit: int = 200) -> list[AuditLog]:
+    result = await db.execute(
+        select(AuditLog).order_by(AuditLog.created_at.desc()).limit(limit)
+    )
+    return list(result.scalars().all())
diff --git a/app/models/__init__.py b/app/models/__init__.py
index 377190b..0bd11a6 100644
--- a/app/models/__init__.py
+++ b/app/models/__init__.py
@@ -1,6 +1,7 @@
 """Import all models so they register with ``Base.metadata``."""
 
 from app.models.associations import role_permissions, user_roles
+from app.models.audit_log import AuditLog
 from app.models.iso_thread import IsoThread
 from app.models.manufacturer import Manufacturer
 from app.models.part_type import PartType
@@ -12,6 +13,7 @@ from app.models.unc_thread import UncThread
 from app.models.user import User
 
 __all__ = [
+    "AuditLog",
     "IsoThread",
     "Manufacturer",
     "PartType",
diff --git a/app/models/audit_log.py b/app/models/audit_log.py
new file mode 100644
index 0000000..3d4cf27
--- /dev/null
+++ b/app/models/audit_log.py
@@ -0,0 +1,23 @@
+from datetime import datetime
+
+from sqlalchemy import DateTime, ForeignKey, String, func
+from sqlalchemy.orm import Mapped, mapped_column
+
+from app.core.database import Base
+
+
+class AuditLog(Base):
+    __tablename__ = "audit_logs"
+
+    id: Mapped[int] = mapped_column(primary_key=True)
+    created_at: Mapped[datetime] = mapped_column(
+        DateTime(timezone=True), server_default=func.now(), index=True
+    )
+    user_id: Mapped[int | None] = mapped_column(
+        ForeignKey("users.id", ondelete="SET NULL"), nullable=True, index=True
+    )
+    user_email: Mapped[str] = mapped_column(String(255), nullable=False)
+    action: Mapped[str] = mapped_column(String(16), nullable=False)
+    resource_type: Mapped[str] = mapped_column(String(64), nullable=False)
+    resource_id: Mapped[int | None] = mapped_column(nullable=True)
+    description: Mapped[str] = mapped_column(nullable=False)
diff --git a/app/schemas/audit_log.py b/app/schemas/audit_log.py
new file mode 100644
index 0000000..456e981
--- /dev/null
+++ b/app/schemas/audit_log.py
@@ -0,0 +1,16 @@
+from datetime import datetime
+
+from pydantic import BaseModel, ConfigDict
+
+
+class AuditLogRead(BaseModel):
+    model_config = ConfigDict(from_attributes=True)
+
+    id: int
+    created_at: datetime
+    user_id: int | None
+    user_email: str
+    action: str
+    resource_type: str
+    resource_id: int | None
+    description: str
diff --git a/app/templates/_nav.html b/app/templates/_nav.html
index 6ece4e8..d855dad 100644
--- a/app/templates/_nav.html
+++ b/app/templates/_nav.html
@@ -23,6 +23,9 @@
     {% if user.is_superuser or "part_types:read" in user.permissions %}
       <a href="/admin/part-types">Part Types</a>
     {% endif %}
+    {% if user.is_superuser or "audit_log:read" in user.permissions %}
+      <a href="/admin/audit-log">Audit Log</a>
+    {% endif %}
     <a href="/docs" target="_blank">API docs</a>
   </nav>
   <form method="post" action="/logout" class="logout">
diff --git a/app/templates/admin/audit_log.html b/app/templates/admin/audit_log.html
new file mode 100644
index 0000000..a1521d7
--- /dev/null
+++ b/app/templates/admin/audit_log.html
@@ -0,0 +1,37 @@
+{% extends "base.html" %}
+{% block title %}Audit Log · {{ app_name }}{% endblock %}
+{% block body %}
+{% include "_nav.html" %}
+<main class="container">
+  <h1>Audit Log</h1>
+
+  <div class="card">
+    {% if entries %}
+    <table class="table">
+      <thead>
+        <tr>
+          <th>Time</th>
+          <th>User</th>
+          <th>Action</th>
+          <th>Resource</th>
+          <th>Description</th>
+        </tr>
+      </thead>
+      <tbody>
+        {% for entry in entries %}
+        <tr>
+          <td class="muted" style="white-space:nowrap">{{ entry.created_at.strftime("%Y-%m-%d %H:%M:%S") }}</td>
+          <td>{{ entry.user_email }}</td>
+          <td><span class="badge badge-{{ entry.action }}">{{ entry.action }}</span></td>
+          <td>{{ entry.resource_type }}{% if entry.resource_id %} #{{ entry.resource_id }}{% endif %}</td>
+          <td>{{ entry.description }}</td>
+        </tr>
+        {% endfor %}
+      </tbody>
+    </table>
+    {% else %}
+    <p class="muted">No audit log entries yet.</p>
+    {% endif %}
+  </div>
+</main>
+{% endblock %}
diff --git a/app/web/admin.py b/app/web/admin.py
index b2e30b0..fe75b84 100644
--- a/app/web/admin.py
+++ b/app/web/admin.py
@@ -5,6 +5,7 @@ from fastapi.responses import HTMLResponse, RedirectResponse, Response
 from sqlalchemy.ext.asyncio import AsyncSession
 
 from app.core.database import get_db
+from app.crud import audit as audit_crud
 from app.crud import iso_thread as iso_thread_crud
 from app.crud import manufacturer as manufacturer_crud
 from app.crud import part_type as part_type_crud
@@ -68,10 +69,10 @@ async def create_user(
     is_superuser: bool = Form(False),
     role_ids: list[int] = Form(default=[]),
     db: AsyncSession = Depends(get_db),
-    _: User = Depends(web_require("users:write")),
+    actor: User = Depends(web_require("users:write")),
 ):
     if not await user_crud.get_by_email(db, email):
-        await user_crud.create(
+        created = await user_crud.create(
             db,
             email=email,
             password=password,
@@ -79,6 +80,11 @@ async def create_user(
             is_superuser=is_superuser,
             role_ids=role_ids,
         )
+        await audit_crud.log(
+            db, actor=actor, action="create", resource_type="User",
+            resource_id=created.id,
+            description=audit_crud.describe_create("User", created.id, created.email),
+        )
     return templates.TemplateResponse(
         request,
         "admin/_users_table.html",
@@ -129,21 +135,23 @@ async def update_user(
     is_superuser: bool = Form(False),
     role_ids: list[int] = Form(default=[]),
     db: AsyncSession = Depends(get_db),
-    _: User = Depends(web_require("users:write")),
+    actor: User = Depends(web_require("users:write")),
 ):
     target = await user_crud.get(db, user_id)
     if target is None:
         raise HTTPException(status_code=404, detail="User not found")
-    await user_crud.update(
-        db,
-        target,
-        {
-            "full_name": full_name or None,
-            "password": password or None,
-            "is_active": is_active,
-            "is_superuser": is_superuser,
-            "role_ids": role_ids,
-        },
+    changes = {
+        "full_name": full_name or None,
+        "password": password or None,
+        "is_active": is_active,
+        "is_superuser": is_superuser,
+        "role_ids": role_ids,
+    }
+    await user_crud.update(db, target, changes)
+    await audit_crud.log(
+        db, actor=actor, action="update", resource_type="User",
+        resource_id=user_id,
+        description=audit_crud.describe_update("User", user_id, changes),
     )
     return templates.TemplateResponse(request, "admin/_user_row.html", {"u": target})
 
@@ -152,12 +160,17 @@ async def update_user(
 async def delete_user(
     user_id: int,
     db: AsyncSession = Depends(get_db),
-    _: User = Depends(web_require("users:delete")),
+    actor: User = Depends(web_require("users:delete")),
 ):
     target = await user_crud.get(db, user_id)
     if target is not None:
+        email = target.email
         await user_crud.delete(db, target)
-    # Empty body — HTMX swaps the row out of existence.
+        await audit_crud.log(
+            db, actor=actor, action="delete", resource_type="User",
+            resource_id=user_id,
+            description=audit_crud.describe_delete("User", user_id, email),
+        )
     return Response(status_code=status.HTTP_200_OK)
 
 
@@ -188,15 +201,20 @@ async def create_role(
     description: str = Form(""),
     permission_ids: list[int] = Form(default=[]),
     db: AsyncSession = Depends(get_db),
-    _: User = Depends(web_require("roles:write")),
+    actor: User = Depends(web_require("roles:write")),
 ):
     if not await role_crud.get_by_name(db, name):
-        await role_crud.create(
+        created = await role_crud.create(
             db,
             name=name,
             description=description or None,
             permission_ids=permission_ids,
         )
+        await audit_crud.log(
+            db, actor=actor, action="create", resource_type="Role",
+            resource_id=created.id,
+            description=audit_crud.describe_create("Role", created.id, created.name),
+        )
     return templates.TemplateResponse(
         request,
         "admin/_roles_table.html",
@@ -243,12 +261,18 @@ async def update_role(
     role_id: int,
     permission_ids: list[int] = Form(default=[]),
     db: AsyncSession = Depends(get_db),
-    _: User = Depends(web_require("roles:write")),
+    actor: User = Depends(web_require("roles:write")),
 ):
     role = await role_crud.get(db, role_id)
     if role is None:
         raise HTTPException(status_code=404, detail="Role not found")
-    await role_crud.update(db, role, {"permission_ids": permission_ids})
+    changes = {"permission_ids": permission_ids}
+    await role_crud.update(db, role, changes)
+    await audit_crud.log(
+        db, actor=actor, action="update", resource_type="Role",
+        resource_id=role_id,
+        description=audit_crud.describe_update("Role", role_id, changes),
+    )
     return templates.TemplateResponse(request, "admin/_role_row.html", {"r": role})
 
 
@@ -256,11 +280,17 @@ async def update_role(
 async def delete_role(
     role_id: int,
     db: AsyncSession = Depends(get_db),
-    _: User = Depends(web_require("roles:write")),
+    actor: User = Depends(web_require("roles:write")),
 ):
     role = await role_crud.get(db, role_id)
     if role is not None:
+        name = role.name
         await role_crud.delete(db, role)
+        await audit_crud.log(
+            db, actor=actor, action="delete", resource_type="Role",
+            resource_id=role_id,
+            description=audit_crud.describe_delete("Role", role_id, name),
+        )
     return Response(status_code=status.HTTP_200_OK)
 
 
@@ -287,14 +317,19 @@ async def create_iso_thread(
     pitch_mm: float = Form(...),
     depth_mm: str = Form(""),
     db: AsyncSession = Depends(get_db),
-    _: User = Depends(web_require("iso_threads:write")),
+    actor: User = Depends(web_require("iso_threads:write")),
 ):
-    await iso_thread_crud.create(
+    thread = await iso_thread_crud.create(
         db,
         diameter_mm=diameter_mm,
         pitch_mm=pitch_mm,
         depth_mm=float(depth_mm) if depth_mm.strip() else None,
     )
+    await audit_crud.log(
+        db, actor=actor, action="create", resource_type="IsoThread",
+        resource_id=thread.id,
+        description=audit_crud.describe_create("IsoThread", thread.id, f"M{thread.diameter_mm}×{thread.pitch_mm}"),
+    )
     return templates.TemplateResponse(
         request,
         "admin/_iso_threads_table.html",
@@ -340,19 +375,21 @@ async def update_iso_thread(
     pitch_mm: float = Form(...),
     depth_mm: str = Form(""),
     db: AsyncSession = Depends(get_db),
-    _: User = Depends(web_require("iso_threads:write")),
+    actor: User = Depends(web_require("iso_threads:write")),
 ):
     thread = await iso_thread_crud.get(db, thread_id)
     if thread is None:
         raise HTTPException(status_code=404, detail="ISO thread not found")
-    await iso_thread_crud.update(
-        db,
-        thread,
-        {
-            "diameter_mm": diameter_mm,
-            "pitch_mm": pitch_mm,
-            "depth_mm": float(depth_mm) if depth_mm.strip() else None,
-        },
+    changes = {
+        "diameter_mm": diameter_mm,
+        "pitch_mm": pitch_mm,
+        "depth_mm": float(depth_mm) if depth_mm.strip() else None,
+    }
+    await iso_thread_crud.update(db, thread, changes)
+    await audit_crud.log(
+        db, actor=actor, action="update", resource_type="IsoThread",
+        resource_id=thread_id,
+        description=audit_crud.describe_update("IsoThread", thread_id, changes),
     )
     return templates.TemplateResponse(
         request, "admin/_iso_thread_row.html", {"t": thread}
@@ -363,11 +400,17 @@ async def update_iso_thread(
 async def delete_iso_thread(
     thread_id: int,
     db: AsyncSession = Depends(get_db),
-    _: User = Depends(web_require("iso_threads:delete")),
+    actor: User = Depends(web_require("iso_threads:delete")),
 ):
     thread = await iso_thread_crud.get(db, thread_id)
     if thread is not None:
+        name = f"M{thread.diameter_mm}×{thread.pitch_mm}"
         await iso_thread_crud.delete(db, thread)
+        await audit_crud.log(
+            db, actor=actor, action="delete", resource_type="IsoThread",
+            resource_id=thread_id,
+            description=audit_crud.describe_delete("IsoThread", thread_id, name),
+        )
     return Response(status_code=status.HTTP_200_OK)
 
 
@@ -399,15 +442,20 @@ async def create_unc_thread(
     series: UncSeries = Form(...),
     depth_in: str = Form(""),
     db: AsyncSession = Depends(get_db),
-    _: User = Depends(web_require("unc_threads:write")),
+    actor: User = Depends(web_require("unc_threads:write")),
 ):
-    await unc_thread_crud.create(
+    thread = await unc_thread_crud.create(
         db,
         diameter_fraction=diameter_fraction,
         tpi=tpi,
         series=series,
         depth_in=float(depth_in) if depth_in.strip() else None,
     )
+    await audit_crud.log(
+        db, actor=actor, action="create", resource_type="UncThread",
+        resource_id=thread.id,
+        description=audit_crud.describe_create("UncThread", thread.id, f"{thread.diameter_fraction}-{thread.tpi} {thread.series.value}"),
+    )
     return templates.TemplateResponse(
         request,
         "admin/_unc_threads_table.html",
@@ -456,20 +504,22 @@ async def update_unc_thread(
     series: UncSeries = Form(...),
     depth_in: str = Form(""),
     db: AsyncSession = Depends(get_db),
-    _: User = Depends(web_require("unc_threads:write")),
+    actor: User = Depends(web_require("unc_threads:write")),
 ):
     thread = await unc_thread_crud.get(db, thread_id)
     if thread is None:
         raise HTTPException(status_code=404, detail="UNC thread not found")
-    await unc_thread_crud.update(
-        db,
-        thread,
-        {
-            "diameter_fraction": diameter_fraction,
-            "tpi": tpi,
-            "series": series,
-            "depth_in": float(depth_in) if depth_in.strip() else None,
-        },
+    changes = {
+        "diameter_fraction": diameter_fraction,
+        "tpi": tpi,
+        "series": series,
+        "depth_in": float(depth_in) if depth_in.strip() else None,
+    }
+    await unc_thread_crud.update(db, thread, changes)
+    await audit_crud.log(
+        db, actor=actor, action="update", resource_type="UncThread",
+        resource_id=thread_id,
+        description=audit_crud.describe_update("UncThread", thread_id, changes),
     )
     return templates.TemplateResponse(
         request, "admin/_unc_thread_row.html", {"t": thread}
@@ -480,11 +530,17 @@ async def update_unc_thread(
 async def delete_unc_thread(
     thread_id: int,
     db: AsyncSession = Depends(get_db),
-    _: User = Depends(web_require("unc_threads:delete")),
+    actor: User = Depends(web_require("unc_threads:delete")),
 ):
     thread = await unc_thread_crud.get(db, thread_id)
     if thread is not None:
+        name = f"{thread.diameter_fraction}-{thread.tpi} {thread.series.value}"
         await unc_thread_crud.delete(db, thread)
+        await audit_crud.log(
+            db, actor=actor, action="delete", resource_type="UncThread",
+            resource_id=thread_id,
+            description=audit_crud.describe_delete("UncThread", thread_id, name),
+        )
     return Response(status_code=status.HTTP_200_OK)
 
 
@@ -511,14 +567,19 @@ async def create_manufacturer(
     url: str = Form(...),
     logo_url: str = Form(""),
     db: AsyncSession = Depends(get_db),
-    _: User = Depends(web_require("manufacturers:write")),
+    actor: User = Depends(web_require("manufacturers:write")),
 ):
-    await manufacturer_crud.create(
+    created = await manufacturer_crud.create(
         db,
         name=name,
         url=url,
         logo_url=logo_url.strip() or None,
     )
+    await audit_crud.log(
+        db, actor=actor, action="create", resource_type="Manufacturer",
+        resource_id=created.id,
+        description=audit_crud.describe_create("Manufacturer", created.id, created.name),
+    )
     return templates.TemplateResponse(
         request,
         "admin/_manufacturers_table.html",
@@ -564,19 +625,17 @@ async def update_manufacturer(
     url: str = Form(...),
     logo_url: str = Form(""),
     db: AsyncSession = Depends(get_db),
-    _: User = Depends(web_require("manufacturers:write")),
+    actor: User = Depends(web_require("manufacturers:write")),
 ):
     m = await manufacturer_crud.get(db, manufacturer_id)
     if m is None:
         raise HTTPException(status_code=404, detail="Manufacturer not found")
-    await manufacturer_crud.update(
-        db,
-        m,
-        {
-            "name": name,
-            "url": url,
-            "logo_url": logo_url.strip() or None,
-        },
+    changes = {"name": name, "url": url, "logo_url": logo_url.strip() or None}
+    await manufacturer_crud.update(db, m, changes)
+    await audit_crud.log(
+        db, actor=actor, action="update", resource_type="Manufacturer",
+        resource_id=manufacturer_id,
+        description=audit_crud.describe_update("Manufacturer", manufacturer_id, changes),
     )
     return templates.TemplateResponse(
         request, "admin/_manufacturer_row.html", {"m": m}
@@ -587,11 +646,17 @@ async def update_manufacturer(
 async def delete_manufacturer(
     manufacturer_id: int,
     db: AsyncSession = Depends(get_db),
-    _: User = Depends(web_require("manufacturers:delete")),
+    actor: User = Depends(web_require("manufacturers:delete")),
 ):
     m = await manufacturer_crud.get(db, manufacturer_id)
     if m is not None:
+        name = m.name
         await manufacturer_crud.delete(db, m)
+        await audit_crud.log(
+            db, actor=actor, action="delete", resource_type="Manufacturer",
+            resource_id=manufacturer_id,
+            description=audit_crud.describe_delete("Manufacturer", manufacturer_id, name),
+        )
     return Response(status_code=status.HTTP_200_OK)
 
 
@@ -622,14 +687,19 @@ async def create_scope_model(
     manufacturer_id: int = Form(...),
     url: str = Form(""),
     db: AsyncSession = Depends(get_db),
-    _: User = Depends(web_require("scope_models:write")),
+    actor: User = Depends(web_require("scope_models:write")),
 ):
-    await scope_model_crud.create(
+    created = await scope_model_crud.create(
         db,
         name=name,
         manufacturer_id=manufacturer_id,
         url=url.strip() or None,
     )
+    await audit_crud.log(
+        db, actor=actor, action="create", resource_type="ScopeModel",
+        resource_id=created.id,
+        description=audit_crud.describe_create("ScopeModel", created.id, created.name),
+    )
     return templates.TemplateResponse(
         request,
         "admin/_scope_models_table.html",
@@ -677,19 +747,17 @@ async def update_scope_model(
     manufacturer_id: int = Form(...),
     url: str = Form(""),
     db: AsyncSession = Depends(get_db),
-    _: User = Depends(web_require("scope_models:write")),
+    actor: User = Depends(web_require("scope_models:write")),
 ):
     sm = await scope_model_crud.get(db, scope_model_id)
     if sm is None:
         raise HTTPException(status_code=404, detail="Scope model not found")
-    await scope_model_crud.update(
-        db,
-        sm,
-        {
-            "name": name,
-            "manufacturer_id": manufacturer_id,
-            "url": url.strip() or None,
-        },
+    changes = {"name": name, "manufacturer_id": manufacturer_id, "url": url.strip() or None}
+    await scope_model_crud.update(db, sm, changes)
+    await audit_crud.log(
+        db, actor=actor, action="update", resource_type="ScopeModel",
+        resource_id=scope_model_id,
+        description=audit_crud.describe_update("ScopeModel", scope_model_id, changes),
     )
     return templates.TemplateResponse(
         request, "admin/_scope_model_row.html", {"sm": sm}
@@ -700,11 +768,17 @@ async def update_scope_model(
 async def delete_scope_model(
     scope_model_id: int,
     db: AsyncSession = Depends(get_db),
-    _: User = Depends(web_require("scope_models:delete")),
+    actor: User = Depends(web_require("scope_models:delete")),
 ):
     sm = await scope_model_crud.get(db, scope_model_id)
     if sm is not None:
+        name = sm.name
         await scope_model_crud.delete(db, sm)
+        await audit_crud.log(
+            db, actor=actor, action="delete", resource_type="ScopeModel",
+            resource_id=scope_model_id,
+            description=audit_crud.describe_delete("ScopeModel", scope_model_id, name),
+        )
     return Response(status_code=status.HTTP_200_OK)
 
 
@@ -729,10 +803,15 @@ async def create_part_type(
     request: Request,
     name: str = Form(...),
     db: AsyncSession = Depends(get_db),
-    _: User = Depends(web_require("part_types:write")),
+    actor: User = Depends(web_require("part_types:write")),
 ):
     if not await part_type_crud.get_by_name(db, name):
-        await part_type_crud.create(db, name=name)
+        created = await part_type_crud.create(db, name=name)
+        await audit_crud.log(
+            db, actor=actor, action="create", resource_type="PartType",
+            resource_id=created.id,
+            description=audit_crud.describe_create("PartType", created.id, created.name),
+        )
     return templates.TemplateResponse(
         request,
         "admin/_part_types_table.html",
@@ -776,12 +855,18 @@ async def update_part_type(
     part_type_id: int,
     name: str = Form(...),
     db: AsyncSession = Depends(get_db),
-    _: User = Depends(web_require("part_types:write")),
+    actor: User = Depends(web_require("part_types:write")),
 ):
     pt = await part_type_crud.get(db, part_type_id)
     if pt is None:
         raise HTTPException(status_code=404, detail="Part type not found")
-    await part_type_crud.update(db, pt, {"name": name})
+    changes = {"name": name}
+    await part_type_crud.update(db, pt, changes)
+    await audit_crud.log(
+        db, actor=actor, action="update", resource_type="PartType",
+        resource_id=part_type_id,
+        description=audit_crud.describe_update("PartType", part_type_id, changes),
+    )
     return templates.TemplateResponse(
         request, "admin/_part_type_row.html", {"pt": pt}
     )
@@ -791,9 +876,31 @@ async def update_part_type(
 async def delete_part_type(
     part_type_id: int,
     db: AsyncSession = Depends(get_db),
-    _: User = Depends(web_require("part_types:delete")),
+    actor: User = Depends(web_require("part_types:delete")),
 ):
     pt = await part_type_crud.get(db, part_type_id)
     if pt is not None:
+        name = pt.name
         await part_type_crud.delete(db, pt)
+        await audit_crud.log(
+            db, actor=actor, action="delete", resource_type="PartType",
+            resource_id=part_type_id,
+            description=audit_crud.describe_delete("PartType", part_type_id, name),
+        )
     return Response(status_code=status.HTTP_200_OK)
+
+
+# --- Audit Log ---------------------------------------------------------------
+
+
+@router.get("/audit-log", response_class=HTMLResponse)
+async def audit_log_page(
+    request: Request,
+    db: AsyncSession = Depends(get_db),
+    user: User = Depends(web_require("audit_log:read")),
+):
+    return templates.TemplateResponse(
+        request,
+        "admin/audit_log.html",
+        {"user": user, "entries": await audit_crud.list_recent(db)},
+    )
diff --git a/scripts/seed.py b/scripts/seed.py
index 79af52d..f3e970f 100644
--- a/scripts/seed.py
+++ b/scripts/seed.py
@@ -39,11 +39,12 @@ PERMISSIONS = [
     ("part_types:read", "View part types"),
     ("part_types:write", "Create and update part types"),
     ("part_types:delete", "Delete part types"),
+    ("audit_log:read", "View audit log"),
 ]
 
 # Default roles -> permission names. "admin" gets everything.
 ROLES = {
-    "admin": [name for name, _ in PERMISSIONS],
+    "admin": [name for name, _ in PERMISSIONS],  # includes audit_log:read
     "user": ["users:read", "iso_threads:read", "unc_threads:read", "manufacturers:read", "scope_models:read", "part_types:read"],
 }