Please address the comments from this code review:

## Overall Comments
- In `migrate`, `upsertErrors` is a nil `*multierror.Error` when there are no errors, so calling `upsertErrors.ErrorOrNil()` without a nil check will panic; guard with `if upsertErrors != nil && upsertErrors.ErrorOrNil() != nil { ... }` before logging.
- In `populateContainerImageIDV2s`, `container.GetImage()` may return nil for some stored deployments, so accessing `img.GetIdV2()`/`img.GetName()` without a nil check risks a panic; consider skipping containers with nil `Image`.

## Individual Comments

### Comment 1
<location path="migrator/migrations/m_223_to_m_224_populate_deployment_containers_imageidv2/migration_impl.go" line_range="32-41" />
<code_context>
+	db := database.PostgresDB
+	ctx := database.DBCtx
+
+	updatedCount := 0
+	var upsertErrors *multierror.Error
+
+	// Paginate by deployment ID to guarantee forward progress even if some
+	// deployments consistently fail to update.
+	lastID := uuid.Nil.String()
+	for {
+		batchUpdated, newLastID, err := migrateBatch(ctx, db, lastID, &upsertErrors)
+		if err != nil {
+			return err
+		}
+		if newLastID == "" {
+			break
+		}
+		lastID = newLastID
+		updatedCount += batchUpdated
+	}
+
+	log.Infof("Populated image_idv2 for %d deployments", updatedCount)
+	if upsertErrors.ErrorOrNil() != nil {
+		log.Errorf("Errors during migration: %v", upsertErrors.ErrorOrNil())
+	}
</code_context>
<issue_to_address>
**issue (bug_risk):** Protect against nil dereference when checking `upsertErrors` at the end of `migrate`.

`upsertErrors` starts as `var upsertErrors *multierror.Error` and is only set when `migrateBatch` appends an error. If no errors occur, it stays nil and `upsertErrors.ErrorOrNil()` will panic. Please guard this with a nil check, e.g.:

```go
if upsertErrors != nil {
    if err := upsertErrors.ErrorOrNil(); err != nil {
        log.Errorf("Errors during migration: %v", err)
    }
}
```
</issue_to_address>

### Comment 2
<location path="migrator/migrations/m_223_to_m_224_populate_deployment_containers_imageidv2/migration_test.go" line_range="55-56" />
<code_context>
+				makeContainer("sha256:"+strings.Repeat("b", 64), "registry.example.com/img2:v1@sha256:"+strings.Repeat("b", 64)),
+			)
+
+			// Deployment 2: container without image_id — should NOT be migrated.
+			dep2 := makeDeployment("no-image-id",
+				makeContainer("", "registry.example.com/img3:latest"),
+			)
</code_context>
<issue_to_address>
**suggestion (testing):** Add a case for containers with image IDs but missing/empty full image names to cover `newImageV2ID` edge conditions

Current tests cover containers needing migration, missing `image_id`, already-migrated containers, and mixed cases. What’s missing is a DB-backed deployment where `image_id` is set but `image_name_fullname` is empty or absent. Please add such a deployment and assert that both the column and the blob remain unchanged, so we verify we don’t start generating IDs for partially populated image records.
</issue_to_address>

### Comment 3
<location path="migrator/migrations/m_223_to_m_224_populate_deployment_containers_imageidv2/migration_test.go" line_range="60-64" />
<code_context>
+				makeContainer("", "registry.example.com/img3:latest"),
+			)
+
+			// Deployment 3: container that already has image_idv2 — should NOT be migrated.
+			dep3FullName := "registry.example.com/img4:v1@sha256:" + strings.Repeat("c", 64)
+			dep3Digest := "sha256:" + strings.Repeat("c", 64)
+			existingIDV2 := newImageV2ID(dep3FullName, dep3Digest)
+			dep3 := makeDeployment("already-migrated",
+				&storage.Container{
+					Image: &storage.ContainerImage{
</code_context>
<issue_to_address>
**suggestion (testing):** Consider asserting that the serialized blob for already-migrated deployments preserves the existing IdV2 values

For `dep3` you already assert that `image_idv2` retains `existingIDV2`. Since the migration also rewrites the serialized blob, it’d be good to add a blob-level assertion (e.g., `verifyBlobIDV2(dep3)` that checks equality with `existingIDV2` here) to ensure the migration never overwrites previously-correct IdV2 values in the serialized deployment.
</issue_to_address>

### Comment 4
<location path="migrator/migrations/m_223_to_m_224_populate_deployment_containers_imageidv2/migration_impl.go" line_range="27" />
<code_context>
+// deployments.serialized proto blob. Updating the blob is necessary because
+// the platform reprocessor reads the blob and upserts back — if the blob
+// doesn't have id_v2, the reprocessor clobbers the column value.
+func migrate(database *types.Databases) error {
+	pgutils.CreateTableFromModel(database.DBCtx, database.GormDB, schema.CreateTableDeploymentsStmt)
+	db := database.PostgresDB
</code_context>
<issue_to_address>
**issue (complexity):** Consider returning the per-batch non-fatal errors from `migrateBatch` instead of mutating a `**multierror.Error` to simplify error flow and ownership.

You can simplify the error aggregation without changing behavior by removing the `**multierror.Error` and letting `migrateBatch` return its non-fatal errors directly.

### Key change: return batch errors instead of mutating a double pointer

```go
// Before
func migrate(database *types.Databases) error {
    // ...
    var upsertErrors *multierror.Error

    lastID := uuid.Nil.String()
    for {
        batchUpdated, newLastID, err := migrateBatch(ctx, db, lastID, &upsertErrors)
        if err != nil {
            return err
        }
        if newLastID == "" {
            break
        }
        lastID = newLastID
        updatedCount += batchUpdated
    }

    log.Infof("Populated image_idv2 for %d deployments", updatedCount)
    if upsertErrors.ErrorOrNil() != nil {
        log.Errorf("Errors during migration: %v", upsertErrors.ErrorOrNil())
    }
    return nil
}
```

Change `migrate` to accumulate per-batch non-fatal errors returned by `migrateBatch`:

```go
func migrate(database *types.Databases) error {
    pgutils.CreateTableFromModel(database.DBCtx, database.GormDB, schema.CreateTableDeploymentsStmt)
    db := database.PostgresDB
    ctx := database.DBCtx

    updatedCount := 0
    var upsertErrors *multierror.Error

    lastID := uuid.Nil.String()
    for {
        batchUpdated, newLastID, batchErrs, err := migrateBatch(ctx, db, lastID)
        if err != nil {
            return err
        }
        upsertErrors = multierror.Append(upsertErrors, batchErrs)

        if newLastID == "" {
            break
        }
        lastID = newLastID
        updatedCount += batchUpdated
    }

    log.Infof("Populated image_idv2 for %d deployments", updatedCount)
    if err := upsertErrors.ErrorOrNil(); err != nil {
        log.Errorf("Errors during migration: %v", err)
    }
    return nil
}
```

And simplify `migrateBatch`’s signature and internal error handling:

```go
// Before
func migrateBatch(ctx context.Context, db postgres.DB, lastID string, upsertErrors **multierror.Error) (int, string, error) {
    // ...
    if err := rows.Scan(&d.id, &d.serialized); err != nil {
        *upsertErrors = multierror.Append(*upsertErrors, fmt.Errorf("scanning deployment row: %w", err))
        continue
    }
    // ...
    if err := d.UnmarshalVT(dep.serialized); err != nil {
        *upsertErrors = multierror.Append(*upsertErrors, fmt.Errorf("unmarshal deployment %s: %w", dep.id, err))
        continue
    }
    // ...
}
```

Change to:

```go
func migrateBatch(ctx context.Context, db postgres.DB, lastID string) (int, string, *multierror.Error, error) {
    var batchErrs *multierror.Error

    rows, err := db.Query(ctx, `
        SELECT d.id, d.serialized
        FROM deployments d
        WHERE d.id > $2::uuid AND EXISTS (
            SELECT 1 FROM deployments_containers dc
            WHERE dc.deployments_id = d.id
              AND dc.image_id IS NOT NULL AND dc.image_id != ''
              AND dc.image_name_fullname IS NOT NULL AND dc.image_name_fullname != ''
              AND (dc.image_idv2 IS NULL OR dc.image_idv2 = '')
        )
        ORDER BY d.id
        LIMIT $1`, batchSize, lastID)
    if err != nil {
        return 0, "", nil, fmt.Errorf("querying deployments: %w", err)
    }
    defer rows.Close()

    var deps []depRow
    for rows.Next() {
        var d depRow
        if err := rows.Scan(&d.id, &d.serialized); err != nil {
            batchErrs = multierror.Append(batchErrs, fmt.Errorf("scanning deployment row: %w", err))
            continue
        }
        deps = append(deps, d)
    }
    if err := rows.Err(); err != nil {
        return 0, "", nil, fmt.Errorf("iterating deployment rows: %w", err)
    }

    if len(deps) == 0 {
        return 0, "", batchErrs, nil
    }
    newLastID := deps[len(deps)-1].id

    conn, err := db.Acquire(ctx)
    if err != nil {
        return 0, "", batchErrs, fmt.Errorf("acquiring connection: %w", err)
    }
    defer conn.Release()

    batch := &pgx.Batch{}
    batchDeploymentCount := 0

    for _, dep := range deps {
        d := &storage.Deployment{}
        if err := d.UnmarshalVT(dep.serialized); err != nil {
            batchErrs = multierror.Append(batchErrs, fmt.Errorf("unmarshal deployment %s: %w", dep.id, err))
            continue
        }

        blobChanged := populateContainerImageIDV2s(d)

        if blobChanged {
            newSerialized, err := d.MarshalVT()
            if err != nil {
                batchErrs = multierror.Append(batchErrs, fmt.Errorf("marshal deployment %s: %w", dep.id, err))
                continue
            }
            batch.Queue("UPDATE deployments SET serialized = $1 WHERE id = $2",
                newSerialized, pgutils.NilOrUUID(dep.id))
        }

        for idx, container := range d.GetContainers() {
            if idv2 := container.GetImage().GetIdV2(); idv2 != "" {
                batch.Queue(
                    "UPDATE deployments_containers SET image_idv2 = $1 WHERE deployments_id = $2 AND idx = $3",
                    idv2, pgutils.NilOrUUID(dep.id), idx,
                )
            }
        }

        batchDeploymentCount++
    }

    if batch.Len() > 0 {
        results := conn.SendBatch(ctx, batch)
        for i := 0; i < batch.Len(); i++ {
            if _, err := results.Exec(); err != nil {
                batchErrs = multierror.Append(batchErrs, fmt.Errorf("batch exec: %w", err))
            }
        }
        if err := results.Close(); err != nil {
            return 0, "", batchErrs, fmt.Errorf("closing batch results: %w", err)
        }
    }

    return batchDeploymentCount, newLastID, batchErrs, nil
}
```

This keeps:

- The same pagination and updated-count behavior.
- The same distinction between fatal errors (returned `error`) and non-fatal per-row/batch errors (aggregated via `multierror`).
- But removes the double pointer and makes error ownership and flow explicit at the call site.
</issue_to_address>

Please address the comments from this code review:

## Overall Comments
- The `updatedCount` and "Populated image_idv2 for %d deployments" log in `migrate` are incremented per processed deployment, even when a deployment produces no DB updates due to marshal/unmarshal errors; consider tracking and logging a separate counter of successfully updated deployments (or containers) so the log reflects actual changes applied.
- The `batchSize` global is mutated in tests to drive different batch behaviors; if these tests are ever run in parallel or other code starts depending on this package, it may be safer to pass batch size as a parameter (or configuration) to `migrate`/`migrateBatch` instead of relying on a mutable package-level variable.

## Individual Comments

### Comment 1
<location path="migrator/migrations/m_223_to_m_224_populate_deployment_containers_imageidv2/migration_impl.go" line_range="32-41" />
<code_context>
+	db := database.PostgresDB
+	ctx := database.DBCtx
+
+	updatedCount := 0
+	var upsertErrors *multierror.Error
+
+	// Paginate by deployment ID to guarantee forward progress even if some
+	// deployments consistently fail to update.
+	lastID := uuid.Nil.String()
+	for {
+		batchUpdated, newLastID, err := migrateBatch(ctx, db, lastID, &upsertErrors)
+		if err != nil {
+			return err
+		}
+		if newLastID == "" {
+			break
+		}
+		lastID = newLastID
+		updatedCount += batchUpdated
+	}
+
+	log.Infof("Populated image_idv2 for %d deployments", updatedCount)
+	if upsertErrors.ErrorOrNil() != nil {
+		log.Errorf("Errors during migration: %v", upsertErrors.ErrorOrNil())
+	}
</code_context>
<issue_to_address>
**issue (bug_risk):** Guard against nil `upsertErrors` before calling `ErrorOrNil` to avoid a panic when there were no errors.

In `migrate`, `upsertErrors` is declared as `var upsertErrors *multierror.Error` and only modified via `multierror.Append`. If no errors are appended, it remains `nil`, so calling `upsertErrors.ErrorOrNil()` will panic. Please either guard the call, e.g. `if upsertErrors != nil && upsertErrors.ErrorOrNil() != nil { ... }`, or normalize it once (e.g. `if err := multierror.Flatten(upsertErrors); err != nil { ... }`).
</issue_to_address>

### Comment 2
<location path="migrator/migrations/m_223_to_m_224_populate_deployment_containers_imageidv2/migration_impl.go" line_range="159-160" />
<code_context>
+// and full name but no IdV2. Returns true if any container was updated.
+func populateContainerImageIDV2s(deployment *storage.Deployment) bool {
+	changed := false
+	for _, container := range deployment.GetContainers() {
+		img := container.GetImage()
+		if img.GetIdV2() != "" {
+			continue
</code_context>
<issue_to_address>
**issue (bug_risk):** Handle nil `Image` on containers to avoid a potential panic when assigning `IdV2`.

In `populateContainerImageIDV2s`, `container.GetImage()` can return nil. While `img.GetIdV2()` is safe on a nil receiver, `img.IdV2 = idV2` will panic if `img` is nil. Please add a nil check (e.g. `if img == nil { continue }`) before using `img` to avoid crashes when containers lack image data.
</issue_to_address>

### Comment 3
<location path="migrator/migrations/m_223_to_m_224_populate_deployment_containers_imageidv2/migration_test.go" line_range="158-167" />
<code_context>
+}
+
+// verifyBlobIDV2 checks that the serialized blob has correct id_v2 on all containers.
+func (s *migrationTestSuite) verifyBlobIDV2(dep *storage.Deployment) {
+	var serialized []byte
+	err := s.db.QueryRow(s.ctx,
+		"SELECT serialized FROM deployments WHERE id = $1",
+		pgutils.NilOrUUID(dep.GetId())).Scan(&serialized)
+	s.Require().NoError(err)
+
+	updated := &storage.Deployment{}
+	s.Require().NoError(updated.UnmarshalVT(serialized))
+
+	for i, c := range updated.GetContainers() {
+		expected := expectedIDV2(c)
+		s.Equal(expected, c.GetImage().GetIdV2(),
</code_context>
<issue_to_address>
**issue (testing):** verifyBlobIDV2 computes expectations from the mutated blob, which could mask bugs that change image full name or digest

Since `expectedIDV2` reads the full name and digest from `updated`, this check will still pass if the migration incorrectly changes `Image.Id` or `Image.Name.FullName`—as long as `IdV2` is consistent with those mutated fields. To ensure the test catches such regressions, derive the expected IdV2 values from the original `dep` before unmarshalling and compare them to the corresponding containers in `updated` (e.g., by pairing containers by index). This way the test verifies that only `IdV2` changes during migration.
</issue_to_address>

### Comment 4
<location path="migrator/migrations/m_223_to_m_224_populate_deployment_containers_imageidv2/migration_impl.go" line_range="27" />
<code_context>
+// deployments.serialized proto blob. Updating the blob is necessary because
+// the platform reprocessor reads the blob and upserts back — if the blob
+// doesn't have id_v2, the reprocessor clobbers the column value.
+func migrate(database *types.Databases) error {
+	pgutils.CreateTableFromModel(database.DBCtx, database.GormDB, schema.CreateTableDeploymentsStmt)
+	db := database.PostgresDB
</code_context>
<issue_to_address>
**issue (complexity):** Consider simplifying error handling in `migrate`/`migrateBatch` by returning a `*multierror.Error` and centralizing non-fatal error accumulation to reduce indirection and clarify responsibilities.

You can simplify this without changing behavior by (1) removing the pointer-to-pointer error accumulator and (2) slightly separating concerns inside `migrateBatch`.

### 1. Remove `**multierror.Error`

Instead of passing `**multierror.Error` into `migrateBatch`, let `migrateBatch` return a `*multierror.Error` and aggregate it in `migrate`. This keeps ownership clearly in `migrate` and removes the double indirection.

```go
// migrate
func migrate(database *types.Databases) error {
    pgutils.CreateTableFromModel(database.DBCtx, database.GormDB, schema.CreateTableDeploymentsStmt)
    db := database.PostgresDB
    ctx := database.DBCtx

    updatedCount := 0
    var upsertErrors *multierror.Error

    lastID := uuid.Nil.String()
    for {
        batchUpdated, newLastID, batchErrs, err := migrateBatch(ctx, db, lastID)
        if err != nil {
            return err
        }
        upsertErrors = multierror.Append(upsertErrors, batchErrs)

        if newLastID == "" {
            break
        }
        lastID = newLastID
        updatedCount += batchUpdated
    }

    log.Infof("Populated image_idv2 for %d deployments", updatedCount)
    if err := upsertErrors.ErrorOrNil(); err != nil {
        log.Errorf("Errors during migration: %v", err)
    }
    return nil
}
```

```go
// migrateBatch
func migrateBatch(ctx context.Context, db postgres.DB, lastID string) (int, string, *multierror.Error, error) {
    var upsertErrors *multierror.Error

    rows, err := db.Query(ctx, `...`, batchSize, lastID)
    if err != nil {
        return 0, "", nil, fmt.Errorf("querying deployments: %w", err)
    }
    defer rows.Close()

    var deps []depRow
    for rows.Next() {
        var d depRow
        if err := rows.Scan(&d.id, &d.serialized); err != nil {
            upsertErrors = multierror.Append(upsertErrors, fmt.Errorf("scanning deployment row: %w", err))
            continue
        }
        deps = append(deps, d)
    }
    if err := rows.Err(); err != nil {
        return 0, "", nil, fmt.Errorf("iterating deployment rows: %w", err)
    }

    if len(deps) == 0 {
        return 0, "", upsertErrors, nil
    }
    newLastID := deps[len(deps)-1].id

    conn, err := db.Acquire(ctx)
    if err != nil {
        return 0, "", upsertErrors, fmt.Errorf("acquiring connection: %w", err)
    }
    defer conn.Release()

    batch := &pgx.Batch{}
    batchDeploymentCount := 0

    for _, dep := range deps {
        d := &storage.Deployment{}
        if err := d.UnmarshalVT(dep.serialized); err != nil {
            upsertErrors = multierror.Append(upsertErrors, fmt.Errorf("unmarshal deployment %s: %w", dep.id, err))
            continue
        }

        blobChanged := populateContainerImageIDV2s(d)

        if blobChanged {
            newSerialized, err := d.MarshalVT()
            if err != nil {
                upsertErrors = multierror.Append(upsertErrors, fmt.Errorf("marshal deployment %s: %w", dep.id, err))
                continue
            }
            batch.Queue("UPDATE deployments SET serialized = $1 WHERE id = $2",
                newSerialized, pgutils.NilOrUUID(dep.id))
        }

        for idx, container := range d.GetContainers() {
            if idv2 := container.GetImage().GetIdV2(); idv2 != "" {
                batch.Queue(
                    "UPDATE deployments_containers SET image_idv2 = $1 WHERE deployments_id = $2 AND idx = $3",
                    idv2, pgutils.NilOrUUID(dep.id), idx,
                )
            }
        }

        batchDeploymentCount++
    }

    if batch.Len() > 0 {
        results := conn.SendBatch(ctx, batch)
        for i := 0; i < batch.Len(); i++ {
            if _, err := results.Exec(); err != nil {
                upsertErrors = multierror.Append(upsertErrors, fmt.Errorf("batch exec: %w", err))
            }
        }
        if err := results.Close(); err != nil {
            return 0, "", upsertErrors, fmt.Errorf("closing batch results: %w", err)
        }
    }

    return batchDeploymentCount, newLastID, upsertErrors, nil
}
```

### 2. Centralize non-fatal error recording

To make the “log-and-continue” intent explicit and avoid repetition, add a small helper:

```go
func appendNonFatal(acc *multierror.Error, msg string, err error) *multierror.Error {
    if err == nil {
        return acc
    }
    return multierror.Append(acc, fmt.Errorf("%s: %w", msg, err))
}
```

Usage inside `migrateBatch`:

```go
if err := rows.Scan(&d.id, &d.serialized); err != nil {
    upsertErrors = appendNonFatal(upsertErrors, "scanning deployment row", err)
    continue
}

if err := d.UnmarshalVT(dep.serialized); err != nil {
    upsertErrors = appendNonFatal(upsertErrors, fmt.Sprintf("unmarshal deployment %s", dep.id), err)
    continue
}

newSerialized, err := d.MarshalVT()
if err != nil {
    upsertErrors = appendNonFatal(upsertErrors, fmt.Sprintf("marshal deployment %s", dep.id), err)
    continue
}
```

This preserves all existing behavior (same non-fatal vs fatal boundaries and `multierror` semantics) while reducing indirection and clarifying responsibilities.
</issue_to_address>

Please address the comments from this code review:

## Overall Comments
- In `populateContainerImageIDV2s` (and the related helper in the tests), you call `img.GetName().GetFullName()` without checking if `GetName()` returns nil; consider adding a nil check (or using a safer accessor) to avoid panics on deployments with images missing a name.
- The migration accumulates `upsertErrors` with `multierror` but always returns nil from `migrate`; if partial failures should be surfaced (or at least fail CI), consider returning `upsertErrors.ErrorOrNil()` instead of only logging, or explicitly document why partial failure is acceptable.