---
phase: 01-foundation
plan: 02
subsystem: core
tags: [wpf, dotnet10, csom, pnp-framework, serilog, sharepoint, pagination, retry, messaging, csharp]

# Dependency graph
requires:
  - 01-01 (solution scaffold, NuGet packages)
provides:
  - TenantProfile model matching JSON schema (Name/TenantUrl/ClientId)
  - OperationProgress record with Indeterminate factory for IProgress<T> pattern
  - TenantSwitchedMessage and LanguageChangedMessage broadcast-ready via WeakReferenceMessenger
  - SharePointPaginationHelper: async iterator bypassing 5k item limit via ListItemCollectionPosition
  - ExecuteQueryRetryHelper: exponential backoff on 429/503 with IProgress<OperationProgress> surfacing
  - LogPanelSink: custom Serilog ILogEventSink writing to RichTextBox via Dispatcher.InvokeAsync
affects:
  - 01-03 (ProfileService uses TenantProfile)
  - 01-04 (MsalClientFactory uses TenantProfile.ClientId/TenantUrl)
  - 01-05 (TranslationSource sends LanguageChangedMessage; LoggingIntegration uses LogPanelSink)
  - 01-06 (FeatureViewModelBase uses OperationProgress + IProgress<T> pattern)
  - 02-xx (all SharePoint feature services use pagination and retry helpers)

# Tech tracking
tech-stack:
  added: []
  patterns:
    - IAsyncEnumerable<ListItem> with [EnumeratorCancellation] for correct WithCancellation support
    - ListItemCollectionPosition loop (do/while until null) for CSOM pagination past 5k items
    - Exponential backoff: delay = 2^attempt * 5s (10, 20, 40, 80, 160s) up to MaxRetries=5
    - WeakReferenceMessenger messages via ValueChangedMessage<T> base class
    - Dispatcher.InvokeAsync for thread-safe UI writes from Serilog background thread

key-files:
  created:
    - SharepointToolbox/Core/Models/TenantProfile.cs
    - SharepointToolbox/Core/Models/OperationProgress.cs
    - SharepointToolbox/Core/Messages/TenantSwitchedMessage.cs
    - SharepointToolbox/Core/Messages/LanguageChangedMessage.cs
    - SharepointToolbox/Core/Helpers/SharePointPaginationHelper.cs
    - SharepointToolbox/Core/Helpers/ExecuteQueryRetryHelper.cs
    - SharepointToolbox/Infrastructure/Logging/LogPanelSink.cs
  modified: []

key-decisions:
  - "TenantProfile is a plain class (not record) — mutable for System.Text.Json deserialization; fields Name/TenantUrl/ClientId match existing JSON schema casing"
  - "SharePointPaginationHelper uses [EnumeratorCancellation] on ct parameter — required for correct cancellation forwarding when callers use WithCancellation(ct)"
  - "ExecuteQueryRetryHelper uses catch-when filter with IsThrottleException — matches 429/503 status codes and 'throttl' text in message, covers PnP.Framework exception surfaces"

requirements-completed:
  - FOUND-05
  - FOUND-06
  - FOUND-07
  - FOUND-08

# Metrics
duration: 1min
completed: 2026-04-02
---

# Phase 1 Plan 02: Core Models, Messages, and Infrastructure Helpers Summary

**7 Core/Infrastructure files providing typed contracts (TenantProfile, OperationProgress, messages, CSOM pagination helper, throttle-aware retry helper, RichTextBox Serilog sink) — 0 errors, 0 warnings**

## Performance

- **Duration:** 1 min
- **Started:** 2026-04-02T10:04:59Z
- **Completed:** 2026-04-02T10:06:00Z
- **Tasks:** 2
- **Files modified:** 7

## Accomplishments

- All 7 Core/Infrastructure files created and compiling with 0 errors, 0 warnings
- TenantProfile fields match JSON schema exactly (Name/TenantUrl/ClientId)
- OperationProgress record with Indeterminate factory, usable by all feature services via IProgress<T>
- TenantSwitchedMessage and LanguageChangedMessage correctly inherit ValueChangedMessage<T> for WeakReferenceMessenger broadcast
- SharePointPaginationHelper iterates past 5,000 items using ListItemCollectionPosition do/while loop; RowLimit=2000
- ExecuteQueryRetryHelper surfaces retry events via IProgress<OperationProgress> with exponential backoff (10s, 20s, 40s, 80s, 160s)
- LogPanelSink writes color-coded, timestamped entries to RichTextBox via Dispatcher.InvokeAsync for thread safety

## Task Commits

Each task was committed atomically:

1. **Task 1: Core models and WeakReferenceMessenger messages** - `ddb216b` (feat)
2. **Task 2: SharePointPaginationHelper, ExecuteQueryRetryHelper, LogPanelSink** - `c297801` (feat)

**Plan metadata:** (docs commit follows)

## Files Created/Modified

- `SharepointToolbox/Core/Models/TenantProfile.cs` - Plain class; Name/TenantUrl/ClientId match JSON schema
- `SharepointToolbox/Core/Models/OperationProgress.cs` - Record with Indeterminate factory; IProgress<T> contract
- `SharepointToolbox/Core/Messages/TenantSwitchedMessage.cs` - ValueChangedMessage<TenantProfile>; WeakReferenceMessenger broadcast
- `SharepointToolbox/Core/Messages/LanguageChangedMessage.cs` - ValueChangedMessage<string>; WeakReferenceMessenger broadcast
- `SharepointToolbox/Core/Helpers/SharePointPaginationHelper.cs` - Async iterator; ListItemCollectionPosition loop; [EnumeratorCancellation]
- `SharepointToolbox/Core/Helpers/ExecuteQueryRetryHelper.cs` - Retry on 429/503/throttle; exponential backoff; IProgress surfacing
- `SharepointToolbox/Infrastructure/Logging/LogPanelSink.cs` - ILogEventSink; Dispatcher.InvokeAsync; color-coded by level

## Decisions Made

- TenantProfile is a plain mutable class (not a record) — System.Text.Json deserialization requires a parameterless constructor and settable properties; field names match the existing JSON schema exactly to avoid serialization mismatches.
- SharePointPaginationHelper.GetAllItemsAsync decorates `ct` with `[EnumeratorCancellation]` — without this attribute, cancellation tokens passed via `WithCancellation()` on the async enumerable are silently ignored. This is a correctness requirement for callers who use the cancellation pattern.
- ExecuteQueryRetryHelper.IsThrottleException checks for "429", "503", and "throttl" (case-insensitive) — PnP.Framework surfaces HTTP errors in the exception message rather than a dedicated exception type; this covers all known throttle surfaces.

## Deviations from Plan

### Auto-fixed Issues

**1. [Rule 2 - Missing critical functionality] Added [EnumeratorCancellation] attribute to SharePointPaginationHelper**
- **Found during:** Task 2 (dotnet build)
- **Issue:** CS8425 warning — async iterator with `CancellationToken ct` parameter missing `[EnumeratorCancellation]`; without it, cancellation via `WithCancellation(ct)` on the `IAsyncEnumerable<T>` is silently dropped, breaking cancellation for all callers
- **Fix:** Added `using System.Runtime.CompilerServices;` and `[EnumeratorCancellation]` attribute on the `ct` parameter
- **Files modified:** `SharepointToolbox/Core/Helpers/SharePointPaginationHelper.cs`
- **Verification:** Build 0 warnings, 0 errors after fix
- **Committed in:** c297801 (Task 2 commit)

---

**Total deviations:** 1 auto-fixed (Rule 2 — missing critical functionality for correct cancellation behavior)
**Impact on plan:** Fix required for correct operation. One line change, no scope creep.

## Issues Encountered

None beyond the auto-fixed deviation above.

## User Setup Required

None - no external service configuration required.

## Next Phase Readiness

- All contracts in place for plan 01-03 (ProfileService uses TenantProfile)
- All contracts in place for plan 01-04 (MsalClientFactory uses TenantProfile.ClientId/TenantUrl)
- All contracts in place for plan 01-05 (LoggingIntegration uses LogPanelSink; LanguageChangedMessage for TranslationSource)
- All contracts in place for plan 01-06 (FeatureViewModelBase uses OperationProgress + IProgress<T>)
- All Phase 2+ SharePoint feature services can use pagination and retry helpers immediately

---
*Phase: 01-foundation*
*Completed: 2026-04-02*