Sync GitHub instructions with CI packaging

Agent-Logs-Url: https://github.com/jet/equinox/sessions/f16dc17a-e06c-4641-a19b-84d9da5ee184

Co-authored-by: bartelink <206668+bartelink@users.noreply.github.com>

Author: Copilot

.github/agents.md

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+# Agents
+
+## Code Review
+
+### `@code-review`
+
+Performs code review on pull requests, focusing on correctness, style, and adherence to project conventions.
+
+#### Instructions
+
+- This is an F# event-sourcing library. Evaluate changes in the context of functional programming best practices.
+- Verify that new code follows the existing style: 4-space indentation, LF line endings, no trailing whitespace.
+- `TreatWarningsAsErrors` is enabled; flag any code that would produce warnings.
+- Ensure domain logic remains store-agnostic — store-specific code belongs in the respective adapter project, not in `Equinox` or `Equinox.Core`.
+- Confirm that `FsCodec.IEventCodec` is used for all serialization concerns; no direct serializer coupling.
+- Check that new dependencies are truly necessary; this project intentionally minimizes its dependency footprint.
+- Verify tests are not removed or weakened without justification.
+- For integration tests, ensure appropriate skip flags (`EQUINOX_INTEGRATION_SKIP_EVENTSTORE`, `EQUINOX_INTEGRATION_SKIP_COSMOS`) are respected.
+- CI-only pack behavior is enabled when either `CI=true` or Azure Pipelines sets `TF_BUILD`; packaged projects under `src/` and `tools/` opt into documentation generation and package validation from their local `Directory.Build.props`.
+- Build: `dotnet build -c Release`
+- Test: `dotnet test -c Release --report-xunit-trx --ignore-exit-code 8 --results-directory tests/trx`
+  - Exit code 8 is expected when store-dependent test assemblies have all tests skipped.

.github/copilot-instructions.md

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+# Copilot Instructions for Equinox
+
+## Project Overview
+
+Equinox is a set of low-dependency F# libraries for event-sourced processing against stream-based stores.
+It is **not a framework**; consumers compose the libraries to fit their needs.
+
+Related repositories:
+- [FsCodec](https://github.com/jet/FsCodec) — encoding/decoding events
+- [Propulsion](https://github.com/jet/propulsion) — projections and reactions
+- [dotnet-templates](https://github.com/jet/dotnet-templates) — starter project templates
+
+## Repository Layout
+
+| Path | Contents |
+|------|----------|
+| `src/Equinox` | Core library: `Decider`, `Cache`, optimistic concurrency |
+| `src/Equinox.Core` | Shared utilities: `TaskCell`, `Batcher` |
+| `src/Equinox.CosmosStore` | Azure Cosmos DB adapter |
+| `src/Equinox.DynamoStore` | Amazon DynamoDB adapter |
+| `src/Equinox.EventStoreDb` | EventStoreDB (gRPC) adapter |
+| `src/Equinox.MessageDb` | MessageDB (Postgres) adapter |
+| `src/Equinox.MemoryStore` | In-memory store for testing |
+| `src/Equinox.EventStore` | Legacy EventStore TCP adapter (deprecated) |
+| `src/Equinox.SqlStreamStore*` | SqlStreamStore adapters (unmaintained upstream) |
+| `src/Equinox.*.Prometheus` | Prometheus metrics sinks |
+| `tests/` | Unit and integration tests (xUnit v3, MTP v2) |
+| `samples/` | Tutorial scripts, TodoBackend, sample store |
+| `tools/Equinox.Tool` | CLI tool for provisioning and benchmarking |
+
+## Language and Style
+
+- The codebase is **F#**. Follow existing conventions when editing.
+- 4-space indentation, LF line endings, trim trailing whitespace (see `.editorconfig`).
+- `TreatWarningsAsErrors` is enabled globally — all warnings are errors.
+- Prefer minimal dependencies; Equinox intentionally keeps its dependency footprint small.
+- Do not add comments unless they match the existing style or explain something non-obvious.
+
+## Building and Testing
+
+- **SDK**: .NET 10 (see `global.json` for exact version; `rollForward: latestMajor`).
+- **Test runner**: Microsoft Testing Platform v2 (configured in `global.json` `"test"` section).
+- **Build**:
+  ```sh
+  dotnet build -c Release
+  ```
+- **Test** (CI style):
+  ```sh
+  dotnet test -c Release --report-xunit-trx --ignore-exit-code 8 --results-directory tests/trx
+  ```
+  Exit code 8 means all tests in an assembly were skipped (expected in CI without Docker stores).
+- **Repository build**:
+  ```sh
+  dotnet build -c Release
+  ```
+- Integration test skip flags (set to `true` to skip):
+  - `EQUINOX_INTEGRATION_SKIP_EVENTSTORE`
+  - `EQUINOX_INTEGRATION_SKIP_COSMOS`
+- CI-only packaging behavior is activated when either `CI=true` or Azure Pipelines provides `TF_BUILD`; packable projects under `src/` and `tools/` enable documentation-file generation and package validation from their local `Directory.Build.props`.
+- CI runs on Azure Pipelines across Windows, Linux, and macOS.
+
+## Key Design Patterns
+
+- **Decider pattern**: Domain logic lives in `decide`/`interpret` functions that take state and return events.
+  The `Decider<'event, 'state>` type manages the optimistic concurrency loop.
+- **`IEventCodec`**: All serialization is expressed via `FsCodec.IEventCodec`. Use `FsCodec.SystemTextJson.Codec` or `FsCodec.NewtonsoftJson.Codec`.
+- **Access Strategies**: Each store adapter provides strategies for snapshots/unfolds
+  (e.g., `RollingState`, `Snapshot`, `Tip with Unfolds` for CosmosStore).
+- **Caching**: `Equinox.Cache` wraps `System.Runtime.Caching.MemoryCache` to minimize store round-trips.
+- **Store agnosticism**: Domain code should never reference a specific store package.
+  Store wiring is the responsibility of the application composition root.
+
+## PR and Contribution Guidelines
+
+- See `CONTRIBUTING.md` — new features start at −100 points; keep changes focused.
+- Ensure tests pass before submitting. Do not remove or weaken existing tests.
+- Use `CHANGELOG.md` conventions when documenting user-facing changes.