docs: fix documentation drift — engine defaults, Quick Start example, missing template marker and architecture entries (#314)

* Initial plan

* docs: fix documentation drift — engine defaults, Quick Start example, missing marker and architecture entries

Agent-Logs-Url: https://github.com/githubnext/ado-aw/sessions/eb011c3a-d2d2-425e-a15a-1843aaf1e21a

Co-authored-by: jamesadevine <4742697+jamesadevine@users.noreply.github.com>

---------

Co-authored-by: copilot-swe-agent[bot] <198982749+Copilot@users.noreply.github.com>
Co-authored-by: jamesadevine <4742697+jamesadevine@users.noreply.github.com>

Author: Copilot

AGENTS.md

@@ -32,7 +32,8 @@ Alongside the correctly generated pipeline yaml, an agent file is generated from
 │   │   ├── extensions/   # CompilerExtension trait and infrastructure extensions
 │   │   │   ├── mod.rs    # Trait, Extension enum, collect_extensions(), re-exports
 │   │   │   ├── github.rs # Always-on GitHub MCP extension
-│   │   │   └── safe_outputs.rs # Always-on SafeOutputs MCP extension
+│   │   │   ├── safe_outputs.rs # Always-on SafeOutputs MCP extension
+│   │   │   └── tests.rs  # Extension integration tests
 │   │   └── types.rs      # Front matter grammar and types
 │   ├── init.rs           # Repository initialization for AI-first authoring
 │   ├── execute.rs        # Stage 3 safe output execution
@@ -43,6 +44,7 @@ Alongside the correctly generated pipeline yaml, an agent file is generated from
 │   ├── detect.rs         # Agentic pipeline detection (helper for `configure`)
 │   ├── ndjson.rs         # NDJSON parsing utilities
 │   ├── sanitize.rs       # Input sanitization for safe outputs
+│   ├── validate.rs       # Structural input validators (char allowlists, format checks, injection detectors)
 │   ├── agent_stats.rs    # OTel-based agent statistics parsing (token usage, duration, turns)
 │   ├── safeoutputs/      # Safe-output MCP tool implementations (Stage 1 → NDJSON → Stage 3)
 │   │   ├── mod.rs
@@ -861,6 +863,12 @@ Environment variable names are validated against `[A-Za-z_][A-Za-z0-9_]*` to pre
 
 If no passthrough env vars are needed, this marker is replaced with an empty string.
 
+## {{ mcpg_step_env }}
+
+Generates an `env:` block for the "Start MCP Gateway (MCPG)" pipeline step, forwarding pipeline variables required by enabled extensions (e.g., `AZURE_DEVOPS_EXT_PAT` when the Azure DevOps MCP tool is configured). The compiler iterates through all active `CompilerExtension` instances, collects their `required_pipeline_vars()` mappings, de-duplicates by variable name, and emits each as `VAR_NAME: $(VAR_NAME)` in ADO variable-reference syntax.
+
+When no extensions require pipeline variables, this marker is replaced with an empty string and the MCPG step has no `env:` block.
+
 ## {{ mcp_client_config }}
 
 **Removed.** The Copilot CLI `mcp-config.json` is no longer generated at compile time. Instead, it is derived at **pipeline runtime** from MCPG's actual gateway output, matching gh-aw's `convert_gateway_config_copilot.cjs` pattern.

README.md

@@ -78,7 +78,9 @@ The AI will generate a markdown file like:
 ---
 name: "Dependency Updater"
 description: "Checks for outdated dependencies and opens PRs"
-engine: claude-sonnet-4.5
+engine:
+  id: copilot
+  model: claude-sonnet-4.5
 schedule: weekly on monday around 9:00
 pool: AZS-1ES-L-MMS-ubuntu-22.04
 tools:
@@ -225,7 +227,7 @@ the service connections. Approve the permissions and the pipeline is ready.
 | `name` | string | **required** | Human-readable name for the agent |
 | `description` | string | **required** | One-line summary of the agent's purpose |
 | `target` | `standalone` \| `1es` | `standalone` | Pipeline output format |
-| `engine` | string or object | `claude-opus-4.5` | AI model to use |
+| `engine` | string or object | `copilot` | Engine identifier or object with `id`, `model`, `timeout-minutes`, etc. |
 | `schedule` | string or object | — | [Fuzzy schedule expression](#schedule-syntax) |
 | `pool` | string or object | `AZS-1ES-L-MMS-ubuntu-22.04` | Agent pool |
 | `workspace` | `root` \| `repo` | auto | Working directory mode |