# Component: Transport

## Purpose

The Transport component provides a file-based, encrypted, environment-agnostic way to promote configuration artifacts from one ScadaBridge cluster to another through the Central UI. A user with the Design role on the source cluster exports a selected set of templates and supporting artifacts to a `.scadabundle` file. A user with the Admin role on the target cluster uploads the bundle, reviews a diff, resolves conflicts per artifact, and applies it. Import is config-only: it updates the central configuration database; affected instances surface as stale on the existing Deployments page and the user redeploys via the standard flow. Transport does not touch site runtime nodes and does not move runtime state.

As of M8 (T18), Transport is no longer limited to central-only configuration: it also moves **site-scoped configuration** — `Site` definitions, site-scoped `DataConnection`s (protocol connections), and `Instance`s with their override children and area membership. Because site identifiers and connection names differ across environments, a **name-mapping subsystem** (see "Name Mapping") reconciles source references onto target sites/connections at import time. This is still purely a central-configuration-database operation: Transport never deploys to or otherwise touches site cluster nodes — newly imported instances land as `NotDeployed`, and the operator redeploys via the existing pipeline.

## Location

- New project: `src/ZB.MOM.WW.ScadaBridge.Transport/`
- New tests: `tests/ZB.MOM.WW.ScadaBridge.Transport.Tests/`, `tests/ZB.MOM.WW.ScadaBridge.Transport.IntegrationTests/`
- Central UI pages: `src/ZB.MOM.WW.ScadaBridge.CentralUI/Components/Pages/Design/TransportExport.razor`, `TransportImport.razor`
- EF migration in `src/ZB.MOM.WW.ScadaBridge.ConfigurationDatabase/Migrations/` (adds `BundleImportId` column to `AuditLogEntries`)
- This design doc: `docs/requirements/Component-Transport.md`

## Responsibilities

- Define and own the `.scadabundle` file format (ZIP container, `manifest.json`, `content.json` / `content.enc`).
- Resolve artifact dependencies at export time: base templates, shared scripts, external systems, template folders, notification lists, SMTP configs, API keys, API methods.
- Move **site-scoped configuration** (T18): `Site` definitions, site-scoped `DataConnection`s (protocol connections — distinct from External-System `DatabaseConnection`s), and `Instance`s along with their `InstanceAttributeOverride` / `InstanceAlarmOverride` / `InstanceNativeAlarmSourceOverride` / `InstanceConnectionBinding` children and `Area` membership (carried by name).
- Reconcile cross-environment site identifiers and connection names through the **name-mapping subsystem** (`BundleNameMap`): auto-match by identifier/name, operator override via the import-wizard Map step or CLI flags, and per-conflict create-or-bind resolution (see "Name Mapping").
- Compute a **per-line (Myers) diff** for code fields on Modified artifacts (T20) via the pure `LineDiffer`, embedding a size-capped structured line diff in each `ArtifactDiff`. Two independent caps guard the diff: a 400-line **output** cap on the emitted hunk list, and — as of arch-review 05 (Task 22) — a `MaxInputLines` **input** cap (4000 combined lines) that short-circuits the O((N+M)²) Myers trace to a summary-only result (`Truncated = true`, add/remove totals only) so a bloated or crafted bundle cannot OOM the active central node from the import preview.
- Serialize and deserialize all transportable entity types to/from bundle DTOs, carving secret fields into an isolated `SecretsBlock`. A template travels with **all** of its child collections — `TemplateAttribute`, `TemplateAlarm`, `TemplateScript`, `TemplateComposition`, and `TemplateNativeAlarmSource` (including `IsInherited` placeholder rows, which the collision detector depends on) — each field-faithful on Add and reconciled add/update/delete on Overwrite. Field completeness is verified by a reflection round-trip guard over every writable property (Add + Overwrite), and includes the fields earlier revisions dropped: the derived-lock flag `LockedInDerived` on attributes/alarms/scripts, script cadence/timeout (`MinTimeBetweenRuns` / `ExecutionTimeoutSeconds`), and — for instances — the real `AreaName` (the exporter previously emitted `null`, half-shipping the Area-by-name feature). Carrying the native alarm sources is what keeps an imported `InstanceNativeAlarmSourceOverride` from dangling against a source the target template would otherwise lack.
- Encrypt content with AES-256-GCM + PBKDF2-SHA256 (600 000 iterations) when a passphrase is supplied; leave content plaintext with a UI warning and an `UnencryptedBundleExport` audit event when none is given.
- Validate `manifest.json` on upload: format version gating, SHA-256 content hash verification.
- Manage in-memory `BundleSession` objects: 30-minute TTL, 3-strike passphrase lockout per session.
- Compute a per-artifact diff between bundle contents and the target environment, classifying each artifact as Identical, Modified, New, a Blocker (import-stopping), or a Warning (advisory, non-blocking).
- Apply user-supplied conflict resolutions (Add, Overwrite, Skip, Rename) in a single EF transaction, running multi-pass semantic validation before committing: a **script trust gate** (`ScriptTrustValidator.FindViolations` over every non-Skip template / shared / ApiMethod body — bundle import is the fifth script-trust call site, so forbidden-API scripts are rejected at import review, not deferred to runtime), then a minimal name-resolution scan over the merged target (ApiMethod findings fail fast on unresolved SharedScript / ExternalSystem identifiers; template-script findings are advisory warnings), then the full `SemanticValidator` from `ZB.MOM.WW.ScadaBridge.TemplateEngine` over each imported template's per-template `FlattenedConfiguration`.
- Emit `BundleExported`, `BundleImported`, `BundleImportFailed`, `UnencryptedBundleExport`, `BundleImportUnlockFailed`, `BundleImportAlarmScriptUnresolved`, `BundleImportCompositionUnresolved`, and `BundleImportBaseTemplateUnresolved` audit events via `IAuditService`.
- Thread a `BundleImportId` correlation GUID through every per-entity `AuditLogEntry` written during `ApplyAsync` via a scoped `IAuditCorrelationContext`.
- Enforce `RequireDesign` on export and `RequireAdmin` on import both at the Razor page layer and inside the service entrypoints (defense in depth).

## Bundle Format

### File Layout

`.scadabundle` is a renamed `.zip`:

```
bundle.scadabundle
├── manifest.json              # required, NOT encrypted
├── content.json               # plaintext artifact data  (when no passphrase)
└── content.enc                # encrypted artifact data  (when passphrase set)
```

Exactly one of `content.json` or `content.enc` is present. Script bodies (template
scripts, shared scripts, ApiMethod scripts) travel **inline** inside the `content`
blob, not as separate `scripts/` files — a well-formed bundle has exactly two zip
entries (`manifest.json` + one content blob). A separate `scripts/` directory is
**not implemented**: `TransportOptions.MaxBundleEntryCount` (default 4) is a
zip-bomb guard, and the exporter never emits per-script files.

### `manifest.json` (plaintext)

```json
{
  "bundleFormatVersion": 1,
  "schemaVersion": "1.1",
  "createdAtUtc": "2026-05-24T12:34:56Z",
  "sourceEnvironment": "dev-cluster-a",
  "exportedBy": "alice@corp.example",
  "scadaBridgeVersion": "1.4.2",
  "contentHash": "sha256:...",
  "encryption": {
    "algorithm": "AES-256-GCM",
    "kdf": "PBKDF2-SHA256",
    "iterations": 600000,
    "saltB64": "...",
    "ivB64": "..."
  },
  "summary": {
    "templates": 12, "templateFolders": 3, "sharedScripts": 4,
    "externalSystems": 2, "dbConnections": 1,
    "notificationLists": 1, "smtpConfigs": 0, "apiKeys": 2, "apiMethods": 5,
    "sites": 2, "dataConnections": 3, "instances": 8
  },
  "contents": [
    { "type": "Template", "name": "Pump", "version": 5,
      "dependsOn": ["SharedScript:PumpUtils"] },
    { "type": "Template", "name": "Pump.WaterPump", "version": 3,
      "dependsOn": ["Template:Pump", "ExternalSystem:HistorianAPI"] },
    { "type": "Site", "name": "site-a", "version": 1, "dependsOn": [] },
    { "type": "DataConnection", "name": "site-a/PlantOpcUa", "version": 1,
      "dependsOn": ["Site:site-a"] },
    { "type": "Instance", "name": "WaterPump-01", "version": 1,
      "dependsOn": ["Template:Pump.WaterPump", "Site:site-a"] }
  ]
}
```

The manifest is plaintext so the import wizard can preview bundle contents and source provenance before the user supplies a passphrase. (Implementation note: `BundleImporter.LoadAsync` always parses the manifest *and* reads the content blob to verify the SHA-256 hash on every call, regardless of whether a passphrase is available — the "manifest peek" is conceptual rather than a cheap O(manifest) operation. For an encrypted bundle without a passphrase the call surfaces the encrypted-bundle prompt via the validated envelope, so the UI gets the manifest + provenance for free, but the cost is O(bundle-size) per `LoadAsync`. A future `ReadManifestAsync(Stream)` that skips the content read is a deferred optimisation.)

### `content.json` / `content.enc`

- One top-level array per entity type, POCO shapes serialized via `System.Text.Json`. As of schema 1.1 (T18) this includes `sites`, `dataConnections`, and `instances` arrays (`SiteDto`, `DataConnectionDto`, `InstanceDto` + its override-child and connection-binding DTOs) alongside the existing central-config arrays.
- Secret fields (API key hashes, SMTP password, external system credentials, DB connection passwords) live in a nested `secrets` block on each affected entity. Per the D3 "carry full config (encrypted secrets)" decision, a `DataConnection`'s `PrimaryConfiguration` / `BackupConfiguration` (endpoint + credentials) also ride inside this encrypted `SecretsBlock`; they appear in diffs as presence-only and are never echoed in plaintext. A `Site`'s `NodeA`/`NodeB` and `GrpcNodeA`/`GrpcNodeB` addresses travel as ordinary (non-secret) `SiteDto` fields.
- The whole `content` blob is AES-256-GCM encrypted with a key derived via PBKDF2-SHA256 (600 000 iterations) from the user's passphrase, with per-bundle random salt and per-encryption random IV.
- Unencrypted bundles are allowed but the UI warns and audit-tags them `UnencryptedBundleExport`.

### Forward Compatibility

- Unknown top-level entity types in `contents[]` surface in the import preview as "skipped — unsupported in this version" rather than failing the whole import.
- `bundleFormatVersion` newer than what the importer supports produces a hard refusal at upload with a clear upgrade message.
- `schemaVersion` minor increments are **additive-only**. T18 bumped it `1.0 → 1.1` (adding the `sites`/`dataConnections`/`instances` arrays). `bundleFormatVersion` stays `1`; `ManifestValidator` gates solely on `bundleFormatVersion`, so a pre-T18 importer still accepts a 1.1 bundle and simply lists the new site/instance/connection entries as "skipped — unsupported in this version".

## Architecture

```mermaid
%%{init: {'theme':'base', 'themeVariables': {'textColor':'#111111','lineColor':'#555555','edgeLabelBackground':'#ffffff','fontSize':'15px'}}}%%
flowchart TD
    subgraph T["ZB.MOM.WW.ScadaBridge.Transport"]
        EXPORTER["IBundleExporter<br/>ExportAsync(ExportSelection, Passphrase?, ct) → Stream"]
        IMPORTER["IBundleImporter<br/>LoadAsync(stream, Passphrase?, ct) → BundleSession<br/>PreviewAsync(sessionId, ct) → ImportPreview<br/>ApplyAsync(sessionId, resolutions, ct) → ImportResult"]
        RESOLVER["DependencyResolver"]
        SERIALIZER["BundleSerializer<br/>(manifest + content JSON; ZIP packer)"]
        ENCRYPTOR["BundleSecretEncryptor<br/>(AES-256-GCM + PBKDF2)"]
        SESSIONSTORE["BundleSessionStore<br/>(in-memory, TTL'd)"]
        MANIFESTVALIDATOR["ManifestValidator<br/>(schema/version gating, hash check)"]
    end

    classDef start fill:#d5e8d4,stroke:#82b366,color:#111111;
    classDef proc fill:#dae8fc,stroke:#6c8ebf,color:#111111;
    classDef dec fill:#fff2cc,stroke:#d6b656,color:#111111;
    classDef warn fill:#ffe6cc,stroke:#d79b00,color:#111111;
    classDef alt fill:#e1d5e7,stroke:#9673a6,color:#111111;
    classDef muted fill:#f5f5f5,stroke:#999999,color:#666666;
    class EXPORTER,IMPORTER proc
    class RESOLVER,SERIALIZER start
    class ENCRYPTOR alt
    class SESSIONSTORE warn
    class MANIFESTVALIDATOR dec
    class T muted
```

The component is central-hosted. It is registered in `ZB.MOM.WW.ScadaBridge.Host` for central roles only, never for site roles — even when a bundle carries site-scoped config (T18), Transport only writes the central configuration database, never the site clusters. All persistence flows through existing audited repository interfaces in `ZB.MOM.WW.ScadaBridge.ConfigurationDatabase` — the component does not call `DbContext.SaveChangesAsync` directly. `BundleSessionStore` is in-process on the active central node (matching Blazor Server circuit affinity): 30-minute TTL, eviction on expiry, 3-strike passphrase lockout per session, and a `MaxConcurrentImportSessions` cap (default 8; arch-review 05 Task 24) bounding the decrypted-content footprint since each open session pins a fully-decrypted bundle in memory.

**Preview→apply window (recorded decision).** The diff/preview an operator reviews is a point-in-time snapshot; there is **no optimistic concurrency** between preview and apply. If the target config changes in the window between `PreviewAsync` and `ApplyAsync` (another admin edits a template, say), the apply proceeds against the current state — the resolutions are keyed by `(EntityType, Name)`, so they still target the right rows, but the operator may not have seen the latest state in the diff. This is accepted for v1 (single-operator import is the expected workflow, and the terminal Confirm step already gates a typo-resistant environment-name entry). The bundle-format `version` fields are reserved for a future optimistic-concurrency check but are not yet enforced (Underdeveloped 5).

## Export Flow

### UI — 4-Step Wizard (Design nav group)

**Step 1 — Select artifacts.** Templates are rendered as a tree matching the existing Templates page (the `TemplateFolderTree.razor` shared component, used in its new checkbox-selection mode). Tri-state checkboxes on folders (`☑` all, `☐` none, `▣` partial). Search filters the tree in place. Other artifact groups (shared scripts, external systems, notification lists, SMTP configs, API keys, API methods) are flat checkbox lists.

A **Sites & Instances** section (T18) adds a flat list of sites, each row expandable to its instances; selecting a site or individual instances pulls them (and their site-scoped `DataConnection`s) into the bundle. The wizard distinguishes operator-seeded selections from artifacts auto-included by dependency resolution (e.g., an instance's site and bound connections).

**Step 2 — Review dependencies.** The resolver expands the user's selection along these edges:

- `Template A` composes `Template B` → include `B`.
- `Template` references `SharedScript` (by name) → include the script.
- `Template` references `ExternalSystem` → include the definition and its methods.
- `ApiMethod` references `SharedScript` → include the script.
- `NotificationList` references `SmtpConfiguration` → include the SMTP config.
- Any folder containing a selected template is included so the structure is reproducible on import.

The user can toggle "include all dependencies" off (with a warning that the bundle may produce an invalid import).

**Step 3 — Encryption.** Passphrase and confirm. Strength meter. Explicit warning lists every secret field being encrypted. An "Export without encryption" path is logged with the `UnencryptedBundleExport` audit flag.

**Step 4 — Download.** Generated filename pattern: `scadabundle-{sourceEnv}-{yyyy-MM-dd-HHmmss}.scadabundle`. SHA-256 displayed for out-of-band verification.

### Backend

```mermaid
%%{init: {'theme':'base', 'themeVariables': {'textColor':'#111111','lineColor':'#555555','edgeLabelBackground':'#ffffff','fontSize':'15px'}}}%%
flowchart TD
    USER(["User (Design role)"])
    WIZARD["Central UI Export wizard"]
    EXPORTER["IBundleExporter"]
    RESOLVER["DependencyResolver"]
    REPOS[("repositories (read)")]
    SERIALIZER["EntitySerializer"]
    CONTENTJSON["content.json"]
    ENCRYPTOR["BundleSecretEncryptor"]
    CONTENTENC["content.enc<br/>(if passphrase)"]
    MANIFESTBUILDER["ManifestBuilder"]
    MANIFESTJSON["manifest.json"]
    ZIP["ZIP packer → temp file → browser download"]
    AUDIT["IAuditService.LogAsync(BundleExported …)"]

    USER --> WIZARD
    WIZARD --> EXPORTER
    EXPORTER --> RESOLVER
    RESOLVER --> SERIALIZER
    SERIALIZER --> ENCRYPTOR
    ENCRYPTOR --> MANIFESTBUILDER
    MANIFESTBUILDER --> ZIP
    ZIP --> AUDIT

    RESOLVER --> REPOS
    SERIALIZER --> CONTENTJSON
    ENCRYPTOR --> CONTENTENC
    MANIFESTBUILDER --> MANIFESTJSON

    classDef start fill:#d5e8d4,stroke:#82b366,color:#111111;
    classDef proc fill:#dae8fc,stroke:#6c8ebf,color:#111111;
    classDef dec fill:#fff2cc,stroke:#d6b656,color:#111111;
    classDef warn fill:#ffe6cc,stroke:#d79b00,color:#111111;
    classDef alt fill:#e1d5e7,stroke:#9673a6,color:#111111;
    classDef muted fill:#f5f5f5,stroke:#999999,color:#666666;
    class USER,AUDIT start
    class WIZARD,EXPORTER,ZIP proc
    class RESOLVER,SERIALIZER,MANIFESTBUILDER dec
    class ENCRYPTOR alt
    class CONTENTJSON,CONTENTENC,MANIFESTJSON warn
    class REPOS muted
```

Audit event: `BundleExported` — caller, artifact count, content hash, encrypted yes/no, bundle filename.

Authorization: `RequireDesign` on both the Razor page and `IBundleExporter.ExportAsync`.

## Import Flow

### UI — 6-Step Wizard (Admin nav group)

**Step 1 — Upload.** Drag-and-drop or browse. On selection, the manifest is parsed and displayed (source env, exporter, timestamp, content count, SHA-256, encrypted yes/no). The manifest hash is validated against the `content` blob.

**Step 2 — Passphrase** (skipped if the bundle is unencrypted). 3-wrong-attempt lockout invalidates the session.

**Step 3 — Map** (T18; shown only when the bundle carries sites and/or site-scoped connections). For every source `Site` and every source `(site, connection)` the importer first auto-matches against the target environment (sites by `SiteIdentifier`, connections by the site-qualified `{SiteIdentifier}/{Name}` key). The operator confirms or overrides each row: **Map to existing** (bind to a target site/connection) or **Create new** (materialize it from the bundle payload). Any source reference that neither auto-matches nor is set to Create-new becomes a **blocker row** and Apply stays disabled until resolved. The Map step renders only the rows that still require a decision; fully auto-matched references pass through silently.

**Step 4 — Diff & resolve conflicts.** For each artifact in the bundle, compare to existing by name:

- **Identical** (field-by-field) → marked, auto-skipped, cannot be selected.
- **Modified** → shows a real per-line `+/-` diff for code fields (`TemplateScript.Code`, `SharedScript.Code`, `ApiMethod.Script`), rendered by the shared `LineDiffView` component from the structured `lineDiff` payload (T20). User picks Skip / Overwrite / Rename.
- **New** → marked `+ Add`. User can opt to skip individually.

Bulk "Apply to all" at the top (Overwrite / Skip / Rename), overridable per row. Summary line at the bottom: "5 add · 2 overwrite · 1 skip · 0 rename".

Bundle references that cannot be satisfied in either the bundle or the target DB (e.g., a template references a shared script that is neither in the bundle nor pre-existing) appear as **blocker rows** — Apply is disabled until they are resolved (typically by skipping the dependent artifact or re-exporting with dependencies). Unmapped/unmatched sites and connections that the operator did not set to Create-new also surface as blocker rows here, mirroring the Step-3 Map decisions.

**Blocker-scan heuristic boundaries.** The scanner walks `TemplateScript.Code`, `TemplateAttribute.Value`, and `ApiMethod.Script` looking for top-level `Identifier(` or `Identifier.` tokens. To keep the heuristic usable on real script bodies it (a) skips identifiers preceded by `.` (member access — `obj.Method()` does not flag `Method`); (b) does NOT scan `TemplateAttribute.DataSourceReference` (an OPC UA address path, never script source); (c) excludes names **declared locally in the body** — every `LocalFunctionStatement` / `MethodDeclaration` identifier is collected via a Roslyn script-kind parse, so a script's own helper (`decimal ComputeRate(...) => …; return ComputeRate(x);`) is not mistaken for a missing SharedScript; and (d) filters out a `KnownNonReferenceNames` denylist of .NET stdlib types (`Convert`, `DateTimeOffset`, `Regex`, `StringBuilder`, `Parse`, LINQ operators, …), ScadaBridge runtime API roots (`Notify`, `Database`, `ExternalSystem`, `Scripts`, `Instance`, `Parameters`, `Attributes`, `Route`, …), and common SQL keywords that appear inside string literals (`COUNT`, `SELECT`, `FROM`, `HAVING`, `VALUES`, …). Both the diff-step `DetectBlockersAsync` and the Apply-time `RunSemanticValidationAsync` Pass 1 share this filter, so the diff preview and the Apply gate agree.

**Severity split — template-script findings are advisory, ApiMethod findings block.** A residual unresolved identifier (one the heuristic could not filter) is classified by its **origin**. Findings from **template scripts** and **attribute default expressions** are non-blocking **warnings**: they surface as `ConflictKind.Warning` rows in the preview and ride on `ImportResult.Warnings` after a successful apply — the import proceeds because the authoritative design-time **deploy gate re-validates** the script with a real compile (`ScriptCompiler.TryCompile`), so a heuristic false positive here must never stop a valid import. Findings from **ApiMethod scripts** remain **hard errors** (`ConflictKind.Blocker` in preview; `SemanticValidationException` at apply) because inbound API methods have no downstream design-time gate — the import review is their only pre-runtime check. The split is applied identically in `DetectBlockersAsync` and `RunSemanticValidationAsync` Pass 1 so preview and apply agree.

**Step 5 — Confirm.** Final summary plus a "N instances will become stale" warning enumerating affected instances (a real count as of M8 — see "Stale-Instance Signaling"). User types the source environment name to confirm (typo-resistant gate at the prod boundary).

**Step 6 — Result.** Counts, link to the `BundleImported` audit row, link to the Deployments page filtered to the newly stale instances.

### Backend

```mermaid
%%{init: {'theme':'base', 'themeVariables': {'textColor':'#111111','lineColor':'#555555','edgeLabelBackground':'#ffffff','fontSize':'15px'}}}%%
flowchart TD
    USER(["User (Admin role) → uploads bundle"])
    LOAD["IBundleImporter.LoadAsync<br/>· verify SHA-256 (manifest vs content)<br/>· check bundleFormatVersion supported<br/>· decrypt content.enc with passphrase (if encrypted)<br/>· deserialize entities<br/>· open BundleSession (30-min TTL)"]
    PREVIEW["PreviewAsync → diff vs target DB → ImportPreview"]
    REVIEW["(user reviews + resolves conflicts)"]
    APPLY["ApplyAsync(resolutions, BundleNameMap?) — single EF transaction<br/>· run two-tier semantic validation<br/>&nbsp;&nbsp;(minimal name scan + full SemanticValidator)<br/>· resolve/create target sites + connections (name map)<br/>· apply resolutions (add / overwrite / skip / rename)<br/>· upsert TemplateFolder hierarchy<br/>· upsert instances (forced NotDeployed); rewire FKs<br/>· IAuditService.LogAsync(BundleImported …)<br/>· commit"]
    RESULT["ImportResult → UI step 6"]
    DEPLOYMENTS["'View on Deployments →'  (existing page)"]

    USER --> LOAD
    LOAD --> PREVIEW
    PREVIEW --> APPLY
    PREVIEW -.- REVIEW
    APPLY --> RESULT
    RESULT --> DEPLOYMENTS

    classDef start fill:#d5e8d4,stroke:#82b366,color:#111111;
    classDef proc fill:#dae8fc,stroke:#6c8ebf,color:#111111;
    classDef dec fill:#fff2cc,stroke:#d6b656,color:#111111;
    classDef warn fill:#ffe6cc,stroke:#d79b00,color:#111111;
    classDef alt fill:#e1d5e7,stroke:#9673a6,color:#111111;
    classDef muted fill:#f5f5f5,stroke:#999999,color:#666666;
    class USER start
    class LOAD,RESULT proc
    class PREVIEW dec
    class APPLY alt
    class DEPLOYMENTS warn
    class REVIEW muted
```

Authorization: `RequireAdmin` on both the Razor page and `IBundleImporter.*` entrypoints.

### Name Mapping

Site identifiers and connection names are environment-specific, so a bundle exported from `dev-cluster-a` cannot assume those identifiers exist (or mean the same thing) on the target. The **name-mapping subsystem** reconciles source → target references at import time.

**Model (`ZB.MOM.WW.ScadaBridge.Commons`).** `BundleNameMap` carries two collections:

- `SiteMapping(SourceSiteIdentifier, Action, TargetSiteIdentifier?)` — per source site.
- `ConnectionMapping(SourceSiteIdentifier, SourceConnectionName, Action, TargetConnectionName?)` — per source `(site, connection)`.

`Action` is the `MappingAction` enum: **`MapToExisting`** (bind the source reference to a named target site/connection, honouring the chosen conflict resolution) or **`CreateNew`** (materialize the site/connection from the bundle payload — full config, including the encrypted `DataConnection` secrets per D3). `BundleNameMap.Empty` is the no-mapping default for central-only bundles.

**Identity keys.** Sites are matched by `SiteIdentifier`; connections by the **site-qualified** key `{SiteIdentifier}/{Name}`; instances by `UniqueName`.

**Auto-match → operator override → apply.** The importer first auto-matches every source site and connection against the target by these identity keys. The operator confirms/overrides via the Central UI **Map step** (Step 3) or the CLI `--map-site` / `--map-connection` / `--create-missing-*` flags. References that neither auto-match nor are set to Create-new become **blocker rows** (UI) — or, on the CLI without `--create-missing-sites` / `--create-missing-connections`, abort before apply.

**Template second-pass rewires.** Bundles carry template-to-template references by **name**, not id (ids are environment-specific). After the templates are flushed, the importer runs three name-resolution passes over the imported templates so every cross-template FK points at the freshly-persisted target row: the **alarm on-trigger-script** links (`TemplateAlarm.OnTriggerScriptId`), the **composition** edges (`TemplateComposition`), and the **inheritance** edges (`Template.ParentTemplateId`, resolved from `BaseTemplateName` through the same rename/skip resolution map — a `null` base clears a stale edge on Overwrite). Each pass is best-effort: an unresolvable reference leaves the FK null and emits a warning audit row (`BundleImportAlarmScriptUnresolved` / `BundleImportCompositionUnresolved` / `BundleImportBaseTemplateUnresolved`) rather than aborting the import.

**Rename call-site limitation (load-bearing).** A `Rename` resolution renames the entity being imported (e.g. a SharedScript `Foo` → `Bar`), but it does **not** rewrite call sites inside importing scripts — a script body that calls `CallShared("Foo")` still says `Foo` after import. So the target DB can end up with scripts referencing the old name. This is deliberate: Pass 1 name resolution registers **both** the original and renamed names as resolvable (so the import isn't blocked), and the authoritative check is the target's own **deploy-time validation** (`ScriptCompiler.TryCompile` in the Template Engine deploy gate), which recompiles against the actual persisted catalog. Operators renaming a shared dependency must fix the calling scripts on the target (or re-export with the dependency included under its original name).

**FK rewiring at apply.** Inside the single EF transaction the importer resolves or creates the target sites and connections **first**, then upserts instances (forced to `NotDeployed`) and rewires their foreign keys against the resolved targets:

- `InstanceConnectionBinding.DataConnectionId` is resolved via the connection map, with a **Pass-2** that also binds connections which already exist in the target but were not carried in the bundle.
- `InstanceNativeAlarmSourceOverride.ConnectionNameOverride` is rewritten to the **mapped target** connection name.

### Stale-Instance Signaling

There is no explicit stale-mark write. Overwriting a template during import changes its content, which naturally changes the flattened-config hash that `DeploymentService.CompareAsync` computes at query time. The Deployments page already surfaces any instance whose computed hash differs from the deployed snapshot — no new mechanism is required.

As of M8 the import result enumerates affected instances for real (closing the prior `StaleInstanceIds` stub). Before commit, for each **Overwritten** template the importer walks the existing **deployed** target instances of that template and, via the `IStaleInstanceProbe` seam in Commons (implemented in the Deployment Manager over the flattening pipeline), compares each instance's freshly-flattened revision hash against its `DeployedConfigSnapshot.RevisionHash`; instances whose hash has drifted are returned in `ImportResult.StaleInstanceIds`. The probe is optional — when it is not registered the result is an empty set (informational only, never blocking). Freshly-imported `NotDeployed` instances are surfaced as **new**, not stale. Step 5 (Confirm) shows the real count and Step 6 (Result) deep-links the Deployments page filtered to those instances.

## Error Handling

| Where | Failure | Surfaced as |
|---|---|---|
| Upload | Not a zip / missing `manifest.json` | Step 1 error: "Not a valid ScadaBridge bundle" |
| Upload | `bundleFormatVersion` newer than supported | Step 1 error: "Bundle was created by ScadaBridge v{x}; upgrade this cluster" |
| Upload | Content hash mismatch | Step 1 error: "Bundle integrity check failed — file may be corrupt" |
| Unlock | Wrong passphrase | Step 2 error; 3rd wrong attempt invalidates session, audit `BundleImportUnlockFailed` |
| Map | Source site/connection neither auto-matched nor mapped/created | Listed as a blocker row in the Map step (UI) / Diff step; cannot Apply until mapped or set to Create-new. CLI aborts before apply unless `--create-missing-sites` / `--create-missing-connections` is given |
| Map | `CreateNew` selected but the bundle does not carry that site/connection's config | Blocker — Create-new requires the full config to be present in the bundle payload |
| Preview | ApiMethod script references shared script / external system not in bundle and not in target DB | Listed as a **blocker** row in the Diff step; cannot Apply until resolved (no downstream deploy gate for ApiMethods) |
| Preview | Template script references shared script / external system not in bundle and not in target DB | Listed as an advisory **warning** row; import proceeds — the design-time deploy gate re-validates the script authoritatively |
| Apply | Semantic validation fails (call target type mismatch, etc.) | Modal: "Validation failed — N errors", per-error list, no DB writes |
| Apply | DB transaction fails | Rollback; full transactional guarantee — nothing partial lands; `BundleImportFailed` audit row written outside the rolled-back transaction |
| Session | TTL expired | Diff step onward, refresh prompts re-upload |

Imports are all-or-nothing per bundle. A bundle either applies fully or not at all.

## Security

- **AES-256-GCM** for content encryption with **PBKDF2-SHA256 / 600 000 iterations** (OWASP 2023+ guidance), per-bundle random salt, random IV per encryption. The GCM auth tag is verified before decryption — a wrong passphrase fails cleanly.
- **Passphrase never persisted.** It lives only inside the export/import service call path and is discarded after use. No environment variable, no log line.
- **Failed-unlock rate limit:** per-session 3-strike lockout; per-IP-per-hour cap (default 10, configurable) to deter brute force against a stolen bundle. Each failed attempt produces a `BundleImportUnlockFailed` audit row.
- **Bundle size cap** on upload (default 100 MB, configurable) to bound memory.
- **In-transit:** existing HTTPS to the Central UI; no new channel.
- **Audit trail is the chain of custody.** Every export, every import (including aborted ones at validation), and every unlock failure is audit-logged with source env, content hash, encrypted yes/no, and artifact summary.
- **Defense in depth on authorization:** `RequireDesign` (export) and `RequireAdmin` (import) are enforced both on the Razor page and inside `ZB.MOM.WW.ScadaBridge.Transport` service entrypoints. The UI is not the only gate.
- **Bundles are not retained server-side** after download (export) or after `ApplyAsync` commits (import).

## Configuration Audit Trail

Import flows through the same audited repository methods the UI and CLI use, so every artifact mutated by `ApplyAsync` emits the existing per-entity `AuditLogEntry` row:

| Action during import | `AuditLogEntries` rows emitted |
|---|---|
| Template added | `TemplateCreated` + `TemplateAttributeCreated` (×N) + `TemplateScriptCreated` (×N) + … |
| Template overwritten | `TemplateUpdated` + per-field rows (`TemplateAttributeAdded`, `TemplateScriptUpdated`, …) |
| Template skipped | (no rows) |
| Template renamed-on-import | `TemplateCreated` with the new name (existing row untouched) |
| External system overwritten | `ExternalSystemDefinitionUpdated` + per-method rows |
| Notification list added | `NotificationListCreated` + per-recipient rows |
| API key added | `ApiKeyCreated` |
| Imported alarm references missing on-trigger script | `BundleImportAlarmScriptUnresolved` (warning; alarm FK left null) |
| Imported template's composition references missing target template | `BundleImportCompositionUnresolved` (warning; composition row not written) |
| Imported derived template's base template missing (unresolved / skipped) | `BundleImportBaseTemplateUnresolved` (warning; `ParentTemplateId` left null) |

**Correlation:** every per-entity row written during an import carries a new optional `BundleImportId` column (the GUID of the parent `BundleImported` summary row). The repository layer (`CentralUiRepository.QueryConfigurationAuditAsync`) already accepts a `BundleImportId` filter parameter. The Configuration Audit Log Viewer UI surface — a "Bundle Import" filter dropdown and a hyperlink on the `BundleImported` summary row that pre-populates that filter — is a deferred UI follow-up (tracked under Transport-012 in the code review backlog). Until then, an operator can drive the same filter via the CLI `audit query --bundle-import-id <guid>`.

**Schema change:** one EF migration adds:

- `BundleImportId uniqueidentifier NULL` on `AuditLogEntries`.
- Non-clustered index `IX_AuditLogEntries_BundleImportId`.

**Transactional guarantee:** the EF transaction wraps both the entity writes and the audit log writes (existing pattern). A rollback removes both. The `BundleImported` summary row is the final write inside the transaction, so partial audit trails are impossible. A failed import emits a single `BundleImportFailed` row outside the rolled-back transaction.

## CLI

Three commands surface the same Transport operations as the Central UI wizards, designed for test automation. The bundle bytes travel as base64 inside the existing `/management` JSON envelope — no new HTTP endpoints — and the per-request body cap is raised to 200 MB to cover the 100 MB raw-bundle ceiling once base64-inflated.

```bash
scadabridge bundle export  --output FILE --passphrase X [--all | --templates A,B ...] \
                         [--shared-scripts ...] [--external-systems ...] [--db-connections ...] \
                         [--notification-lists ...] [--smtp-configs ...] [--api-keys ...] \
                         [--api-methods ...] [--sites A,B ...] [--instances X,Y ...] \
                         [--include-dependencies] [--source-environment NAME]

scadabridge bundle preview --input FILE --passphrase X
                         # prints PreviewBundleResult JSON: per-row items + add/modified/identical/blocker counts;
                         # also prints a required-mapping summary — for each source site/connection it states the
                         # auto-match ("auto-matches 'X'") or the directive ("use --map-site / --create-missing-sites")

scadabridge bundle import  --input FILE --passphrase X [--on-conflict skip|overwrite|rename] \
                         [--map-site src=dst ...] [--map-connection srcSite/srcName=dstName ...] \
                         [--create-missing-sites] [--create-missing-connections]
                         # one-shot load + preview + apply with a single global policy for Modified rows
                         # Identical → Skip, New → Add, Blocker → abort
```

Selection uses entity **names** rather than IDs so scripts are portable across environments — `--sites` accepts a `SiteIdentifier` (preferred) or friendly name per token, `--instances` accepts a `UniqueName`. The mapping flags are repeatable; a `--map-site`/`--map-connection` token with no `=dst` part (or `=` with an empty right-hand side) means **Create-new**, otherwise it binds to the named existing target. `--create-missing-sites` / `--create-missing-connections` create any still-unmapped source site/connection from the bundle payload instead of aborting. The CLI per-command timeout is 5 minutes (vs the default 30 s for other commands) to comfortably cover large bundles. CLI commands route through `ManagementActor`'s `ExportBundleCommand` / `PreviewBundleCommand` / `ImportBundleCommand` handlers, which delegate to the same `IBundleExporter` / `IBundleImporter` services as the UI.

Exit codes follow the project convention: `0` = success, `1` = command failure (validation, blockers, wrong passphrase), `2` = authorization failure.

## Authorization

| Operation | Required role | Enforced at |
|---|---|---|
| Open Export page / `bundle export` CLI | `RequireDesign` | Razor page authorize attribute + `ManagementActor.GetRequiredRole` |
| `IBundleExporter.ExportAsync` | `RequireDesign` | Service entrypoint |
| Open Import page / `bundle preview` + `bundle import` CLI | `RequireAdmin` | Razor page authorize attribute + `ManagementActor.GetRequiredRole` |
| `IBundleImporter.LoadAsync` / `PreviewAsync` / `ApplyAsync` | `RequireAdmin` | Service entrypoint |
| Configuration Audit Log "Bundle Import" filter | `RequireAdmin` or `Audit` | Existing audit page logic |

## Dependencies

- **`ZB.MOM.WW.ScadaBridge.Commons`** — Bundle manifest and content DTOs (`BundleManifest`, `ExportSelection`, `ImportPreview`, `ImportResolution`, `ImportResult`, `BundleSession`); the name-mapping model (`BundleNameMap`, `SiteMapping`, `ConnectionMapping`, `MappingAction`); transport interface definitions (`IBundleExporter`, `IBundleImporter`, `IBundleSessionStore`, `IAuditCorrelationContext`, `IStaleInstanceProbe`).
- **`ZB.MOM.WW.ScadaBridge.ConfigurationDatabase`** — All repository implementations and `IAuditService` for persistence and per-entity audit emission; `IAuditCorrelationContext` implementation (`AuditCorrelationContext`) registered as a scoped service; EF migration for `BundleImportId`. Site/`DataConnection`/`Instance` transport (T18) reuses the **existing** entities — no new tables or columns.
- **`ZB.MOM.WW.ScadaBridge.DeploymentManager`** — `IStaleInstanceProbe` implementation (`StaleInstanceProbe`) over the flattening pipeline, supplying the real `ImportResult.StaleInstanceIds` enumeration (optional DI registration; absent → empty, informational-only result).
- **`ZB.MOM.WW.ScadaBridge.TemplateEngine`** — Pre-deployment `SemanticValidator` invoked inside `ApplyAsync` before the transaction commits. The importer builds a single-template `FlattenedConfiguration` directly from each imported `TemplateDto` (no inheritance / composition resolution at design time — the deployment-time flatten revalidates against the full instance graph) and feeds it through the validator alongside a `ResolvedScript` catalog combining in-bundle + pre-existing target `SharedScript`s. Validator errors are aggregated per template and surfaced as a `SemanticValidationException` that rolls back the import transaction.

## Interactions

- **Central UI** — Hosts the Export Bundle (`/design/transport/export`) page under the Design nav group and the Import Bundle (`/design/transport/import`) page under the Admin nav group. The import result page links to the Deployments page and to the filtered Configuration Audit Log Viewer.
- **Management Service / CLI** — `ManagementActor` registers three Transport command handlers (`ExportBundleCommand`, `PreviewBundleCommand`, `ImportBundleCommand`) and the CLI ships `bundle export` / `bundle preview` / `bundle import` subcommands. Bundle bytes ride the existing `/management` JSON envelope as base64.
- **Deployment Manager** — Never directly invoked by Transport. Transport-driven template changes propagate to deployed instances through the existing revision-hash drift detection in `DeploymentService.CompareAsync`; the Deployments page surfaces affected instances as stale automatically.
- **Security & Auth** — Provides `RequireDesign` and `RequireAdmin` policies from `ZB.MOM.WW.ScadaBridge.Security`, enforced at both the page and service layers.
- **Audit Log (Configuration)** — Writes `BundleExported` / `BundleImported` / `BundleImportFailed` / `UnencryptedBundleExport` / `BundleImportUnlockFailed` rows via `IAuditService`, plus per-import name-resolution warnings `BundleImportAlarmScriptUnresolved`, `BundleImportCompositionUnresolved`, and `BundleImportBaseTemplateUnresolved`; per-entity rows from audited repositories are correlated by `BundleImportId` via `IAuditCorrelationContext`.

---

## Appendix: Bundle JSON Schema

The `manifest.json` file is always present in the ZIP root and is never encrypted.

```json
{
  "bundleFormatVersion": 1,
  "schemaVersion": "1.1",
  "createdAtUtc": "2026-05-24T12:34:56Z",
  "sourceEnvironment": "dev-cluster-a",
  "exportedBy": "alice@corp.example",
  "scadaBridgeVersion": "1.4.2",
  "contentHash": "sha256:abc123...",
  "encryption": {
    "algorithm": "AES-256-GCM",
    "kdf": "PBKDF2-SHA256",
    "iterations": 600000,
    "saltB64": "<base64-encoded 16-byte random salt>",
    "ivB64":   "<base64-encoded 12-byte random IV>"
  },
  "summary": {
    "templates": 12,
    "templateFolders": 3,
    "sharedScripts": 4,
    "externalSystems": 2,
    "dbConnections": 1,
    "notificationLists": 1,
    "smtpConfigs": 0,
    "apiKeys": 2,
    "apiMethods": 5,
    "sites": 2,
    "dataConnections": 3,
    "instances": 8
  },
  "contents": [
    {
      "type": "Template",
      "name": "Pump",
      "version": 5,
      "dependsOn": ["SharedScript:PumpUtils"]
    },
    {
      "type": "Template",
      "name": "Pump.WaterPump",
      "version": 3,
      "dependsOn": ["Template:Pump", "ExternalSystem:HistorianAPI"]
    },
    {
      "type": "Site",
      "name": "site-a",
      "version": 1,
      "dependsOn": []
    },
    {
      "type": "DataConnection",
      "name": "site-a/PlantOpcUa",
      "version": 1,
      "dependsOn": ["Site:site-a"]
    },
    {
      "type": "Instance",
      "name": "WaterPump-01",
      "version": 1,
      "dependsOn": ["Template:Pump.WaterPump", "Site:site-a"]
    }
  ]
}
```

**Field descriptions:**

| Field | Description |
|---|---|
| `bundleFormatVersion` | Integer. Importer hard-refuses any value higher than what its `TransportOptions.SchemaVersionMajor` supports. Stays `1` through T18. |
| `schemaVersion` | Semver string. Minor increments are additive-only and accepted by older importers. T18 bumped this `1.0 → 1.1` (adding the `sites`/`dataConnections`/`instances` content arrays); a pre-T18 importer lists those new entries as "skipped — unsupported in this version" since `ManifestValidator` gates only on `bundleFormatVersion`. |
| `createdAtUtc` | ISO-8601 UTC timestamp of when the export was created. |
| `sourceEnvironment` | The `SourceEnvironment` name of the exporting cluster (from `TransportOptions`). Displayed in the import wizard and required to be retyped at the confirm step. |
| `exportedBy` | Authenticated username of the person who performed the export. |
| `scadaBridgeVersion` | Application version of the exporting node. Used for diagnostic display only. |
| `contentHash` | `sha256:<hex>` — SHA-256 of the raw `content.json` or `content.enc` bytes (pre-encryption). Verified on upload before any decryption. |
| `encryption` | Present only when a passphrase was supplied. Contains the KDF parameters and the per-bundle random salt and IV needed to re-derive the key and decrypt. Omitted for plaintext bundles. |
| `encryption.algorithm` | Always `"AES-256-GCM"` in v1. |
| `encryption.kdf` | Always `"PBKDF2-SHA256"` in v1. |
| `encryption.iterations` | PBKDF2 iteration count. Defaults to 600 000 (configurable via `TransportOptions.Pbkdf2Iterations`). |
| `encryption.saltB64` | Base64-encoded 16-byte random salt generated at export time. |
| `encryption.ivB64` | Base64-encoded 12-byte (GCM standard) random IV generated at export time. |
| `summary` | Artifact count by type, for display in the import wizard's upload step without needing to decrypt content. Schema 1.1 adds `sites` / `dataConnections` / `instances` counts. |
| `contents` | Ordered list of all artifacts in the bundle. Order is topological (base templates before derived; sites before their connections and instances). Each entry carries the artifact's name (connections use the site-qualified `{SiteIdentifier}/{Name}`), the schema `version` at export time, and its direct `dependsOn` edges for dependency display in the export wizard's Step 2. T18 adds the `Site`, `DataConnection`, and `Instance` entry `type`s. |
