# Architecture Review 05 — Design-Time Pipeline: Templates, Deployment, Transport, Script Analysis

Reviewer domain: `src/ZB.MOM.WW.ScadaBridge.TemplateEngine`, `src/ZB.MOM.WW.ScadaBridge.DeploymentManager`, `src/ZB.MOM.WW.ScadaBridge.Transport`, `src/ZB.MOM.WW.ScadaBridge.ScriptAnalysis`, their design docs (`docs/requirements/Component-TemplateEngine.md`, `Component-Transport.md`, `Component-ScriptAnalysis.md`, `Component-DeploymentManager.md`) and test projects. All findings cite code actually read.

## Scope

- **Template Engine**: flattening (`Flattening/FlatteningService.cs`), collision detection (`CollisionDetector.cs`), acyclicity (`CycleDetector.cs`), revision hashing (`Flattening/RevisionHashService.cs`), lock rules (`LockEnforcer.cs`), diffs (`Flattening/DiffService.cs`), validation (`Validation/ValidationService.cs`, `Validation/SemanticValidator.cs`, `Validation/ScriptCompiler.cs`), authoring services (`TemplateService.cs`, `TemplateInheritanceResolver.cs`).
- **Deployment Manager**: `DeploymentService.cs` (deploy/lifecycle pipeline, idempotency reconciliation), `OperationLockManager.cs`, `FlatteningPipeline.cs`, `StateTransitionValidator.cs`, `StaleInstanceProbe.cs`, `ArtifactDeploymentService.cs`.
- **Transport**: `Import/BundleImporter.cs` (3,832 lines — load/preview/apply), `Export/BundleExporter.cs`, `Export/DependencyResolver.cs` (skimmed), `Serialization/EntitySerializer.cs`/`EntityDtos.cs`, `Encryption/BundleSecretEncryptor.cs` + `BundleManifestAad.cs`, `Import/LineDiffer.cs`, `Import/ArtifactDiff.cs`, `Import/BundleSessionStore.cs`, `TransportOptions.cs`.
- **Script Analysis**: `ScriptTrustPolicy.cs`, `ScriptTrustValidator.cs`, `RoslynScriptCompiler.cs`, `ScriptCompileSurface.cs`.
- Cross-component seam checked: Inbound API compiled-handler cache (`src/ZB.MOM.WW.ScadaBridge.InboundAPI/InboundScriptExecutor.cs`) as a consumer of Transport-imported `ApiMethod` rows; `ManagementActor` native-alarm-source override handlers.

## Maturity Verdict

This slice is **unusually well-engineered in its failure-path plumbing** — the deploy pipeline's query-before-redeploy reconciliation, cancellation-token-safe failure writes, ref-counted operation locks, AES-GCM+AAD bundle crypto with zip-bomb caps and passphrase lockout, and the fused two-pass script trust validator are all production-grade and well beyond typical internal-tool quality. However, the **Transport import apply path has serious correctness holes** that undercut the whole promotion story: imported templates silently lose their inheritance edge, their per-script cadence/timeout fields, and their native alarm sources — three distinct silent-data-loss paths, none covered by the otherwise substantial integration test suite. The flattener has one real algorithmic bug (repeated composed templates lose grandchild members), the revision hash omits native alarm sources (breaking staleness detection for that member class), and the central node's validation path leaks Roslyn script assemblies on every Deployments-page comparison. The core design is sound; the defects are concentrated in the newest surface area (M8 Transport, native alarms) where spec, DTOs, and apply code drifted apart.

---

## Findings — Stability & Correctness

### [Critical] Bundle import drops template inheritance edges — derived templates land as root templates
`TemplateDto.BaseTemplateName` (`Serialization/EntityDtos.cs:115`) is populated at export (`Serialization/EntitySerializer.cs:55`) and even diffed in preview (`Import/ArtifactDiff.cs:65`), but **the apply path never consumes it**. `BundleImporter.BuildTemplate` (`Import/BundleImporter.cs:1524-1562`) never sets `ParentTemplateId`; the Overwrite branch (`BundleImporter.cs:1466-1484`) updates only `Description`/`FolderId` and the three child collections; the two second-pass rewires cover alarm→script FKs (`ResolveAlarmScriptLinksAsync`, line 1907) and compositions (`ResolveCompositionEdgesAsync`, line 1993) — there is **no inheritance-edge pass** (`grep -n 'Parent' BundleImporter.cs` returns nothing). The only code that wires `ParentTemplateId` from `BaseTemplateName`, `EntitySerializer.FromBundleContent` (`EntitySerializer.cs:357-360`), is invoked **only from tests** (`tests/.../EntitySerializerTests.cs`).

**Failure scenario:** export `Pump` + derived `Pump.WaterPump` from dev (the manifest explicitly records `dependsOn: ["Template:Pump"]` — `Component-Transport.md:79-80`); import into prod. `WaterPump` is created with `ParentTemplateId = null`. `FlatteningPipeline.BuildTemplateChainAsync` (`DeploymentManager/FlatteningPipeline.cs:176-192`) produces a one-element chain; every inherited attribute/alarm/script vanishes from the flattened config. Because validation validates *what's there*, an instance with no bindings on the missing members can deploy "successfully" with a silently amputated configuration. Neither `tests/ZB.MOM.WW.ScadaBridge.Transport.Tests` nor `Transport.IntegrationTests` contains any inheritance round-trip test (grep for `BaseTemplateName|ParentTemplateId` hits only serializer unit tests).

### [High] Imported template scripts lose `MinTimeBetweenRuns` and `ExecutionTimeoutSeconds`
`TemplateScriptDto` carries both fields (`EntityDtos.cs:148-151`), but the importer drops them on **both** paths: `BuildTemplate` (Add/Rename — `BundleImporter.cs:1550-1560`) and `SyncTemplateScriptsAsync` (Overwrite — the `changed` comparison and field copy at `BundleImporter.cs:~1836-1851` cover Code/TriggerType/TriggerConfiguration/Params/Return/IsLocked only). Both fields participate in the revision hash (`RevisionHashService.cs:87-90`), so the drift is invisible until redeploy, at which point a WhileTrue script's re-fire cadence or a per-script timeout silently reverts to default on the target environment. Same-class omissions: `LockedInDerived` is not carried in the DTO at all (no hits in `EntityDtos.cs`/`EntitySerializer.cs`), so a base template's derived-lock policy does not survive promotion.

### [High] Template `NativeAlarmSources` are not transported, but instance-level overrides of them are
There is no `TemplateNativeAlarmSourceDto`; `BuildTemplate` copies only attributes/alarms/scripts, and none of the `SyncTemplate*` overwrite helpers touch native alarm sources — yet `InstanceNativeAlarmSourceOverrideDto` **does** travel and is applied (`EntityDtos.cs:292`, `BundleImporter.cs:3325-3338`). Consequences: (a) a template imported as **Add** has no native alarm mirrors at all; (b) an **Overwrite** leaves the target's existing sources untouched and the divergence is invisible because `ArtifactDiff.CompareTemplate` (`Import/ArtifactDiff.cs:54-105`) doesn't diff them either; (c) the carried instance overrides dangle and are *silently ignored* at flatten (`FlatteningService.ApplyInstanceNativeAlarmSourceOverrides`, `FlatteningService.cs:781` — missing canonical name → `continue`). This contradicts `Component-TemplateEngine.md:59-64` which makes native alarm sources first-class template members.

### [High] Flattening silently drops grandchild members when the same template is composed twice in one subtree
The recursive composed-member resolvers share one `visited` set down the recursion (`FlatteningService.cs:285-297` for attributes; identical pattern for alarms `:649-660`, scripts `:913-924`, native sources `:761-772`). The direct members of a repeated module still resolve (added before the `visited` check), but the **descent into its nested compositions is skipped** on the second occurrence.

**Failure scenario:** template X composes Y twice (slots `y1`, `y2`); Y composes Z. Flattening produces `y1.*`, `y1.z.*`, `y2.*` — but **not `y2.z.*`**. No validation error fires (the members simply don't exist in the flattened config), so the instance deploys with the second slot's nested sensor/alarm/script members missing. `CollisionDetector.CollectComposedMembers` (`CollisionDetector.cs:126-143`) has the same shared-`visited` early-return, and there it skips even the repeated module's *direct* members — so collision detection is also blind under the second slot. The `visited` set is the right tool for cycle-guarding but the wrong tool for slot deduplication: composition is by-slot, not by-template. Fix is to key the guard on the *path* (prefix) or track only the current recursion stack.

### [High] Revision hash and diff omit `NativeAlarmSources` — no staleness signal for native-alarm changes
`RevisionHashService.HashableConfiguration` (`RevisionHashService.cs:116-152`) hashes Attributes, Alarms, Scripts, Connections — **not** `FlattenedConfiguration.NativeAlarmSources` (populated at `FlatteningService.cs:135`). Editing a template's native alarm source (connection, source reference, condition filter) or an instance override therefore does not change the revision hash: the Deployments page never flags the instance stale, `DeploymentService.GetDeploymentComparisonAsync` reports `IsStale = false`, and sites keep mirroring the old alarm source indefinitely until some unrelated change forces a redeploy. This contradicts the spec's own claim that overrides "participate in the revision hash — changes … re-deploy as expected" (`Component-TemplateEngine.md:215`), which is implemented for connection-binding overrides but not for the native-alarm member class. `DiffService` should be audited for the same omission.

### [High] Bundle import leaves stale compiled Inbound API handlers serving old code
`ApplyApiMethodsAsync` (`BundleImporter.cs:2625`) writes `ApiMethod` rows through `IInboundApiRepository` — a DB-level write. The Inbound API's singleton `InboundScriptExecutor` caches compiled delegates **by method name with no content-based invalidation** (`InboundAPI/InboundScriptExecutor.cs:311-331`: `_scriptHandlers.TryGetValue(method.Name, …)` → serve cached delegate) and caches known-bad methods the same way (`:39, :58-62`). An import that Overwrites an ApiMethod script keeps the **old delegate** serving (HTTP 200 with stale behavior); an import that *fixes* a previously-broken method keeps returning "Script compilation failed" from `_knownBadMethods` until restart. This is the exact failure mode already documented in project memory for DB-direct edits — Transport import is a DB-direct edit at scale, and nothing in `ApplyAsync` signals the executor. Cross-cluster deployments make this worse: the cache lives per central node.

### [High] Locked native alarm sources can be overridden at instance level — lock not enforced anywhere
Spec: "Lock applies to the entire source" (`Component-TemplateEngine.md:114`). Reality: `ApplyInstanceNativeAlarmSourceOverrides` (`FlatteningService.cs:775-792`) applies the override with **no lock check** — contrast the attribute path (`:309 if (existing.IsLocked) continue`) and alarm path (`:337`). `ResolvedNativeAlarmSource` doesn't even carry `IsLocked` (the inherit-time `lockedNames` set at `:676` is local and discarded). The management command path has no check either: `ManagementActor.HandleSetInstanceNativeAlarmSourceOverride` (`ManagementService/ManagementActor.cs:882-909`) upserts unconditionally after site-scope authorization. A site-scoped operator can repoint a *locked* native alarm binding to an arbitrary connection/source reference — precisely what locking exists to prevent on a read-only alarm mirror.

### [Medium] Post-success audit failure flips a committed Success deployment record to Failed
`DeployInstanceAsync` commits the terminal Success status (`DeploymentService.cs:304-306`), runs post-success side effects (correctly swallowed, `:970-1005`), then calls `_auditService.LogAsync` **inside the same try** (`:330-332`). If that audit write throws (transient DB fault, serialization), the catch block (`:343-397`) unconditionally sets `record.Status = Failed` and persists it — central now reports Failed while the site runs the new config, the exact divergence the surrounding comments (`:298-303`) were written to prevent. It also violates the repo convention "audit-write failure NEVER aborts the user-facing action". The audit call should be outside the try or individually guarded like `TryLogLifecycleTimeoutAsync` (`:1034-1066`) already is for lifecycle timeouts.

### [Medium] Deleting a `NotDeployed` instance still requires a live site round-trip
`StateTransitionValidator.CanDelete` explicitly allows delete-from-NotDeployed as "central-side record cleanup (no live site config to tear down)" (`StateTransitionValidator.cs:40-49`), but `DeploymentService.DeleteInstanceAsync` (`DeploymentService.cs:546-585`) unconditionally sends `DeleteInstanceCommand` to the site and fails on timeout. A Transport-imported instance (always lands `NotDeployed`) targeted at a site that is unreachable or not yet commissioned is **undeletable** through the normal path. The two components disagree about the same design sentence.

### [Medium] Import blocker heuristic can hard-block a valid import with no operator override
The Pass-1 name scan (`RunSemanticValidationAsync`, `BundleImporter.cs:3603-3692`; shared with `DetectBlockersAsync:751-818`) flags any `PascalCase(`-shaped token not in the enumerative `KnownNonReferenceNames` denylist (`:853-874`) as a missing SharedScript/ExternalSystem and **throws `SemanticValidationException`** at apply — rolling back the whole import. Any script that defines a local PascalCase method (`decimal ComputeRate(...)` then `ComputeRate(x)`), uses a stdlib type not on the list (`Regex.Match`, `StringBuilder`, `Json`), or embeds SQL keywords outside the nine listed, is a false positive with no "proceed anyway" escape hatch — the operator must edit scripts or re-cut the bundle. The denylist will drift forever. Conversely `Regex`/`StringBuilder` being absent from the list means the heuristic fires on innocent code today. Consider downgrading Pass-1 findings on *template scripts* to warnings (the deploy gate re-validates authoritatively) and keeping hard-block only for `ApiMethod` scripts, or adding an explicit ignore resolution.

### [Medium] `OperationLockManager` is single-node in-memory; concurrent ops via the standby node aren't excluded
Documented as acceptable ("lost on central failover", `OperationLockManager.cs:12-13`) and the implementation itself is careful (ref-counting, reservation-before-wait, exception-filter cleanup — `:46-129`). Residual risk: nothing structurally prevents both central nodes from executing mutating instance ops concurrently if traffic bypasses Traefik's active-node routing (direct ports 9001/9002 are documented in CLAUDE.md). Optimistic concurrency on `DeploymentRecord` is the backstop, but instance-state writes (`DisableInstanceAsync:456-458`) are last-write-wins. Low probability, but worth an explicit invariant (reject management ops on the non-active node).

---

## Findings — Performance

### [High] Every validation run compiles every script with Roslyn — CPU heavy and leaks loaded assemblies on the central node
`ValidationService.ValidateScriptCompilation` (`ValidationService.cs:256-273`) calls `ScriptCompiler.TryCompile` per script; that runs `ScriptTrustValidator.FindViolations` (a fresh `CSharpCompilation.CreateScriptCompilation` over the **entire TPA reference set**, `ScriptTrustValidator.cs:114-124`) *plus* `RoslynScriptCompiler.Compile` → `CSharpScript.Create(...).Compile()` (`RoslynScriptCompiler.cs:70-71`). `Script.Compile()` on success emits and loads the script assembly via Roslyn's `InteractiveAssemblyLoader`, which is **not collectible** — each compiled script permanently occupies loader/metadata memory in the central host.

This sits on hot paths: `FlatteningPipeline.FlattenAndValidateAsync` (`FlatteningPipeline.cs:161-167`) is invoked (a) per deploy, (b) per instance by `DeploymentService.GetDeploymentComparisonAsync` (`DeploymentService.cs:652`) — i.e. **at query time whenever the Deployments page computes staleness**, and (c) per deployed instance by `StaleInstanceProbe` during every template-overwriting bundle import (`BundleImporter.ComputeStaleInstanceIdsAsync:1242-1327`). A 50-instance environment with 10 scripts each = 500 full trust-compilations + 500 script-assembly loads per Deployments-page staleness sweep, unbounded over process lifetime. There is **no compile-result cache**. Fix: cache `TryCompile` verdicts keyed by SHA-256 of code (the verdict is a pure function of code + policy), and/or skip `ValidateScriptCompilation` on read-only comparison paths (staleness needs the hash, not a compile).

### [Medium] `LineDiffer` worst case is O((N+M)²) memory with no input cap
The Myers implementation snapshots the full V frontier per edit distance (`LineDiffer.cs:157-204`: `trace.Add((int[])v.Clone())` with `v` of length `2(N+M)+1`, up to `N+M` rounds). Two ~10,000-line scripts with no common lines ⇒ ~20k rounds × 160 KB ≈ **3+ GB** transient allocation during `PreviewAsync`. `maxLines` (400) caps only the *output* (`:66-92`); nothing caps the *inputs*, and the bundle size cap (100 MB) comfortably admits such scripts. A crafted (or merely bloated) bundle can OOM the active central node from the import preview. Cap input line counts (fall back to the `<N lines>` summary beyond a threshold) or use the linear-space Myers variant.

### [Medium] Any template with a folder, parent, or composition can never diff `Identical`
`ArtifactDiff.CompareTemplate` compares `FolderNameOf`/`BaseTemplateNameOf`/`CompositionTargetNameOf` placeholder strings (`"<id:5>"`) against real incoming names (`ArtifactDiff.cs:64-65, 100, 674-693`), so `FolderName`/`BaseTemplateName`/`Compositions.*` always register as changed for such templates. Effect: the wizard's "Identical → auto-skipped" contract (`Component-Transport.md:222`) never applies to structured templates; every re-import of an unchanged bundle shows spurious Modified rows and, if bulk-Overwrite is chosen, generates needless audit rows and stale-instance probing. The preview loop already hydrates templates (`BundleImporter.cs:379-388`); passing the folder/template name maps it also builds (`:365-366`) into `CompareTemplate` would fix all three placeholders cheaply.

### [Low] `LoadAsync` is O(bundle) even when only the manifest is needed, and each load double-opens the zip
Acknowledged in the design doc itself (`Component-Transport.md:90` — deferred `ReadManifestAsync`). Combined with sessions holding the full decrypted content (`BundleSession.DecryptedContent`) for up to 30 minutes and no cap on concurrent session count (`BundleSessionStore.cs:38`), N concurrent 100 MB uploads pin N×~200 MB. The T-007 zeroing on apply/failure (`BundleImporter.cs:1105, 1194`) is good; a session-count cap would round it out.

### [Low] Import apply is one long EF transaction with per-entity audit rows and four intermediate flushes
`ApplyAsync` (`BundleImporter.cs:960-1098`) holds a relational transaction across full semantic validation (Roslyn-free — fine), all entity staging, per-row `IAuditService.LogAsync` calls, and stale-instance probing (which itself re-flattens per instance, see the Roslyn finding). For a large bundle this is minutes of open-transaction lock footprint on the shared config DB while the Blazor circuit waits. The CLI's raised 5-minute timeout acknowledges the symptom.

---

## Findings — Security / Trust Model

### [Medium] Deny-list gaps: `Environment.Exit`/`FailFast` (site-node kill), `Environment.GetEnvironmentVariable` (secret read)
`ScriptTrustPolicy.ForbiddenScopes` (`ScriptTrustPolicy.cs:36-45`) blocks IO/Process/Threading/Reflection/Net/Interop/Win32, but the `System` namespace root types remain fully available: a template script containing `Environment.Exit(0)` compiles cleanly against the surface and **terminates the site-runtime process** on first trigger — a one-line denial of service of an entire site node from the Design role. `Environment.FailFast`, `Environment.GetEnvironmentVariable` (exfiltrate `SCADABRIDGE_API_KEY`-class secrets via `Notify`/`ExternalSystem.Call`), and `GC.Collect` loops are similarly unblocked. These are cheap adds to `ForbiddenScopes` (as fully-qualified type-or-member entries) or to `ForbiddenIdentifiers`.

### [Medium] `System.Data` allowance is an intentional but unbounded network hole
Site scripts may use raw ADO.NET (`Database.Connection` returns `DbConnection`; `System.Data.Common` is necessarily bindable — `ScriptCompileSurface.cs:119`). `System.Data` is absent from `ForbiddenScopes`, so if the site-runtime execution reference set includes any concrete provider (e.g. `Microsoft.Data.SqlClient`, which the Database helper itself needs), a script can `new SqlConnection("Server=attacker;...")` — an arbitrary-host network channel that the `System.Net` deny was meant to close. The semantic pass will not flag it (SqlClient is not under a forbidden scope). Worth either denying provider namespaces (`Microsoft.Data`, `System.Data.SqlClient`, `System.Data.Odbc`, …) while keeping `System.Data.Common` types reachable only via the `Database` helper, or documenting the accepted risk explicitly in `Component-ScriptAnalysis.md`.

### [Medium] Reflection-gateway member list misses `GetTypes`, `Invoke`, `EntryPoint`, `DeclaredMembers`
`ReflectionGatewayMembers` (`ScriptTrustPolicy.cs:66-88`) blocks `GetMethod`/`InvokeMember`/etc. but not `Invoke` (on `MethodInfo`/`Delegate`), `GetTypes`, `EntryPoint`, `DeclaredMethods`. Pass 1 usually compensates — any expression whose resolved member's containing type is under `System.Reflection` is flagged semantically (`ScriptTrustValidator.cs:180-212`) — but in the documented **TPA-degraded fallback mode** (`ScriptTrustPolicy.cs:207-245`) resolution weakens and Pass 2 becomes the primary defence for chained accesses; the syntactic list should be closed under the obvious invocation members since it exists precisely for that mode. Cheap hardening.

### [Medium] Transport import bypasses the script trust gate entirely
`ApplyAsync` writes template scripts, shared scripts, and API-method scripts to the DB without ever invoking `ScriptTrustValidator` (`RunSemanticValidationAsync` at `BundleImporter.cs:3603` is name-resolution + `SemanticValidator` only). Compensating controls exist downstream — the deploy gate re-validates template scripts (`ScriptCompiler.TryCompile`), the Inbound API re-checks trust at lazy compile — but the layering claim in `Component-ScriptAnalysis.md` ("all call sites delegate…") now has a fifth write path with no gate, and the Inbound API's check happens at *serve time* on the production node rather than at *import review time*. Running `FindViolations` over imported script bodies during Pass 2 (they're already in memory) would restore the design-time boundary and give the operator the finding in the wizard instead of a runtime 500.

### Positive observations (crypto & envelope)
`BundleSecretEncryptor` is textbook: AES-256-GCM with 16-byte salt / 12-byte nonce / 16-byte tag, PBKDF2-SHA256 600k iterations, fresh salt+nonce per encrypt (`BundleSecretEncryptor.cs:14-58`). The T-005 AAD binding of non-derivative manifest fields (`BundleManifestAad.cs:45-55`, verified in `LoadAsync` at `BundleImporter.cs:252-255`) makes the source-environment confirmation gate tamper-evident — a genuinely thoughtful touch. T-006 zip-bomb caps validate central-directory headers before any decompression (`BundleImporter.cs:296-338`); T-003 lockout is keyed by content hash so a second tab/CLI can't sidestep it (`BundleSessionStore.cs:40-47, 122-167`); T-007 zeroes decrypted plaintext on both success and failure. Key management is passphrase-only with no persistence — appropriate for the file-carry threat model, with the residual (documented) weakness that unencrypted export is allowed and only audit-flagged.

---

## Findings — Conventions & Spec Drift

### [Medium] Instance alarm overrides implement less than the spec grants
`Component-TemplateEngine.md:113` says instance-overridable alarm fields include **Description and On-Trigger Script reference**; `ApplyInstanceAlarmOverrides` (`FlatteningService.cs:328-355`) applies only `TriggerConfigurationOverride` and `PriorityLevelOverride`. Either the doc or the entity/flattener should move.

### [Medium] `ArtifactDiff` child-equality predicates miss fields that the import sync *does* write
`AttributesEqual` omits `ElementDataType` and `LockedInDerived` (`ArtifactDiff.cs:646-651`); `AlarmsEqual` omits the on-trigger script reference (`:653-658`); `ScriptsEqual` omits `MinTimeBetweenRuns`/`ExecutionTimeoutSeconds` (`:660-666`). A bundle differing only in those fields classifies **Identical → auto-skipped → silently not imported** (for the fields the sync would have written) — the mirror image of the false-Modified problem above. Diff predicates and sync-helper `changed` predicates should be generated from one field list per entity so they cannot drift (they already have, in both directions).

### [Low] Bundle format spec advertises a `scripts/` directory that is never produced, while `MaxBundleEntryCount` defaults to 4
`Component-Transport.md:45-47` documents optional `scripts/template-{id}-{name}.cs` entries; no code writes or reads them, and `TransportOptions.MaxBundleEntryCount = 4` (`TransportOptions.cs:22`) would reject a bundle that actually used the feature for more than two scripts. Remove from the spec or note it as unimplemented.

### [Low] `ScriptCompiler.TryCompile` surfaces only the first violation/error
`Validation/ScriptCompiler.cs:42,47` return `violations[0]` / `errors[0]`; an operator fixing a script with five issues gets five deploy round-trips. Both underlying APIs return full lists — join them.

### [Low] `RevisionHashService` determinism contract is fragile but guarded
Hash stability depends on alphabetical property declaration order in the `Hashable*` records (`RevisionHashService.cs:12-19, 113-115`); the guard test (`HashableRecords_PropertiesDeclaredAlphabetically`) exists, which is the right mitigation. Note for maintainers: adding `NativeAlarmSources` (see the High finding) will change all hashes — plan it as a deliberate migration (one-time global staleness) rather than a patch.

### Positive observations (conventions)
`DeploymentService` is exemplary on the repo's own rules: `CancellationToken.None` for failure/audit writes after cancellation (`DeploymentService.cs:355-372`), timeout-audit entries for all lifecycle verbs, reconciliation preserving operator-intended Disabled state (`:895-907`), terminal-status-before-side-effects ordering (`:298-306`), and the notify-and-fetch PendingDeployment TTL rationale (`:283-290`) is documented where the decision lives. `CycleDetector.BuildLookup` duplicate-Id tolerance and the Id-0-is-legitimate handling (`CycleDetector.cs:21-27, 56-59`) show real defect-driven hardening. `ScriptTrustPolicy`'s `DefaultReferences` vs `AnalysisReferences` separation with the loud TPA-degradation flag (`ScriptTrustPolicy.cs:207-245`) is a well-reasoned two-layer defence.

---

## Underdeveloped Areas

1. **Transport site/instance wave (M8) shipped ahead of its template-fidelity basics.** Instances, connections, name-mapping, FK rewiring, and stale-probing are all implemented and tested (`SiteInstanceImportTests.cs`, `CompositionImportTests.cs`, rollback-failure tests), but the older template payload silently loses inheritance, cadence/timeout, derived-lock flags, and native alarm sources (findings above). The DTO layer (`EntitySerializer.FromBundleContent`) actually implements more fidelity than the apply path uses — the importer re-implements DTO→entity mapping by hand (`BuildTemplate`) and drifted.
2. **No import test exercises a derived template.** `Transport.IntegrationTests` covers round-trip, conflict resolution, composition edges, semantic validation failure — but grep shows zero inheritance coverage. A single `export(base+derived) → import → flatten` test would have caught the Critical finding.
3. **No flattening test for repeated composition.** `TemplateEngine.Tests/Flattening` exists but the shared-`visited` semantics (same template in two slots of one subtree) is untested; same for `CollisionDetector`.
4. **Deferred items acknowledged in docs but load-bearing:** manifest-only `ReadManifestAsync` (perf), Configuration-Audit-Log "Bundle Import" filter UI (Transport-012), rename call-site rewriting ("call sites are not rewritten in v1" — `BundleImporter.cs:1519-1522`, meaning a Rename resolution on a shared script produces a bundle whose importing templates still call the *old* name, satisfied only because the name-set registers both — the *target DB* ends up with scripts calling a name that may not exist there; only Pass-1's dual registration hides it at import time).
5. **`ArtifactDiff` version fields are permanently null** (`ArtifactDiff.cs:33-37`) — the manifest's per-artifact `version` numbers are display-only; no optimistic concurrency exists between preview and apply, so a target edited between Preview and Apply is silently overwritten (session TTL is 30 min — a real window).
6. **Compile-surface parity relies on three hand-maintained mirrors** (`ScriptCompileSurface`, `TriggerCompileSurface`, Central-UI `SandboxScriptHost`), guarded by reflection tests for two of them and representative-script tests for the third (`Component-ScriptAnalysis.md:141-145`). Adequate but fragile; a source-generator would eliminate the class of drift.
7. **`SemanticValidator` call-target extraction is string-based** and self-admittedly cannot resolve dynamic child names (`SemanticValidator.cs:43-56` — leaf-name fallback accepts any composed script with a matching leaf, so a wrong-child `Children[x].CallScript("Y")` passes design-time validation). Documented tradeoff, but worth a warning-level finding rather than silence.

---

## Prioritized Recommendations

1. **[Critical] Wire template inheritance in the import apply path.** Add a `ResolveInheritanceEdgesAsync` pass mirroring `ResolveCompositionEdgesAsync` (resolve `BaseTemplateName` against Local + target by name, honouring Rename), run it after the template flush, and run `CycleDetector.DetectInheritanceCycle`/`DetectCompositionCycle` over the merged graph before commit (the importer currently performs **no** acyclicity check — a crafted bundle can persist a composition cycle that the authoring path would reject). Add a derived-template round-trip integration test.
2. **[High] Close the import data-loss set in one sweep:** carry `MinTimeBetweenRuns`/`ExecutionTimeoutSeconds` through `BuildTemplate` + `SyncTemplateScriptsAsync`; add `LockedInDerived` to the attribute/alarm/script DTOs and syncs; add `TemplateNativeAlarmSourceDto` (or block export of templates that have native alarm sources until supported). Drive diff predicates and sync predicates from a single per-entity field list.
3. **[High] Fix the repeated-composition `visited` bug** in the four `ResolveComposed*Recursive` methods and `CollisionDetector.CollectComposedMembers` — guard on recursion *path*, not global template Id.
4. **[High] Add `NativeAlarmSources` to `RevisionHashService` (and `DiffService`)** as a planned hash-migration, restoring staleness detection for native-alarm edits.
5. **[High] Cache script-compile verdicts by code hash** and stop loading script assemblies on validation-only paths; skip `ValidateScriptCompilation` in `GetDeploymentComparisonAsync`/`StaleInstanceProbe` (staleness needs only the hash). This removes both the CPU spike and the non-collectible assembly leak from the Deployments page and bundle imports.
6. **[High] Invalidate Inbound API handler caches on import** — publish an ApiMethod-changed notification from `ApplyAsync` (or key `_scriptHandlers` by `(name, scriptHash)`), covering the management-path gotcha already in project memory at the same time.
7. **[High] Enforce locks on native alarm source overrides** at both `ManagementActor.HandleSetInstanceNativeAlarmSourceOverride` and `FlatteningService.ApplyInstanceNativeAlarmSourceOverrides` (carry `IsLocked` on `ResolvedNativeAlarmSource`).
8. **[Medium] Harden the deny-list:** add `System.Environment` members (`Exit`, `FailFast`, `GetEnvironmentVariable(s)`, `SetEnvironmentVariable`), close the reflection-gateway list (`Invoke`, `GetTypes`, `EntryPoint`), and decide/document the `System.Data` provider posture.
9. **[Medium] Deployment audit-write isolation:** move the post-success `LogAsync` in `DeployInstanceAsync` out of the try (or guard it) so an audit fault can never flip a committed Success record to Failed; skip the site round-trip when deleting `NotDeployed` instances.
10. **[Medium] Bound `LineDiffer` inputs; fix `ArtifactDiff` placeholder comparisons** (pass folder/template name maps into `CompareTemplate`) so Identical classification works for structured templates; consider an "ignore blocker" resolution for the Pass-1 heuristic on template scripts.
