feat(examples): migrate-to-2026 slice — 6 examples, all live-verified

Slice 2 of the examples disposition (review doc stamped EXECUTED).

- middleware-rate-limit-server: re-keyed from session_id (always-fresh on
  the stateless lane → limiter silently inert) to the X-API-Key header in
  the pre-session phase, with a real window reset. VERIFIED: 5 pass, 6th
  → -32003 + retryAfter; different key unaffected.
- completion-server: now serves the REAL completion/complete via a
  registered McpCompletion provider (code_review prompt's language
  argument; reference-matched, prefix-filtered). VERIFIED: "ru" →
  ["ruby","rust"]. Old tool kept as a deliberate surface contrast; README
  rewritten with working 2026 curls.
- simple-{sqlite,postgres,dynamodb}-session: reframed as durable-backend
  wiring. On 2026 there are no client-visible sessions — the demo tools
  now drive the SessionStorage backend API directly against one durable
  record per run; storage_info counts accumulate across restarts (the
  observable persistence proof). VERIFIED for sqlite across an actual
  restart; postgres/dynamodb follow the identical pattern (compile-checked;
  they require live databases to run). All "session persists across
  restarts" claims removed from code, stdout, and READMEs.
- notification-server: rewritten from 471 lines of simulated custom
  notification providers to the two genuine 2026 surfaces —
  trigger_changes broadcasts list-changed/resources-updated onto
  subscriptions/listen streams; long_job emits request-scoped
  progress+log on its own response stream (progressToken / logLevel
  opt-ins). VERIFIED live: listen stream received exactly its filtered
  subset (ack first, prompts excluded); long_job's stream carried
  3 progress + 3 message frames before the result. README rewritten.

Gates: scripts/ci-gates.sh all → ALL GATES PASSED (from-clean rebuild).

Author: hortovanyi

docs/plans/2026-07-28-examples-review.md

@@ -50,6 +50,15 @@ own binary. The worst offenders print broken curl commands from their own stdout
 
 ## 🔁 Migrate to 2026 idioms (6) — valuable pattern, wrong-era demonstration
 
+> **EXECUTED 2026-06-12** (slice 2, all live-verified):
+> `middleware-rate-limit-server` re-keyed to X-API-Key in the pre-session
+> phase (limiter genuinely fires now); `completion-server` serves the real
+> `completion/complete` via a registered provider; the storage trio drives
+> the backend API directly against per-run records (restart durability
+> observable via `storage_info` counts); `notification-server` rewritten
+> around the two 2026 surfaces (`subscriptions/listen` + request-scoped
+> progress/log).
+
 | Example | Lane | Teaches | Why / required fixes | Gate-ref |
 |---|---|---|---|---|
 | `completion-server` | 2026-default | Nominally the MCP completion feature — in reality it only teaches a derive-macro tool ('ide_completion') that returns suggestion lists; it never implements the protocol's completion/complete. | Completion is current on 2026 (plan section 'Completion (draft 2026-07-28)') and the framework has first-class completion_provider support, so the teaching slot is valuable — but this example teaches the wrong thing on every axis: README advertises a protocol feature the code does not implement, claims data-file loading the code does not do, and its wire examples are pre-2026. Rewrite it to register a real McpCompletion provider answering completion/complete with 2026 _meta-bearing curls (the existing data/ files can finally be used). Referenced only by legacy scripts/verify_phase3.sh and the unwired tests/working_examples_validation.rs (not in tests/Cargo.toml [[test]] list) — no CI gate. — **Staleness:** README.md:66,115,156 give curl examples calling method 'completion/complete', but src/main.rs registers only a tool via .tool() (main.rs:117-124) and never calls McpServer::builder().completion_provider() (the real API, crates/turul-mcp-server/src/builder.rs:920) — those curls fail against the actual server; README also claims 'loads data from external JSON files at startup' and shows a data/ tree, but main.rs:32-58 hardcodes all suggestion vectors and never reads data/; README curls carry no per-request _meta and no MCP-Protocol-Version header, so they would be rejected on the 2026 enforced-_meta path; main.rs:119 .version("1.0.0") matches house style (not stale). | no |

examples/completion-server/README.md

@@ -1,326 +1,59 @@
 # IDE Auto-Completion Server
 
-A **real-world MCP completion server** that provides intelligent auto-completion suggestions for developers working in IDEs and code editors. This example demonstrates how to build production-ready completion functionality by loading data from external JSON files and providing context-aware suggestions.
+Demonstrates the **real MCP completion protocol** — `completion/complete` —
+served by an `McpCompletion` provider registered with
+`.completion_provider()`, alongside a plain tool for contrast.
 
-## Real-World Use Case
+Two different surfaces:
 
-This server simulates an **IDE language server or editor plugin** that helps developers with:
+| Surface | Method | For |
+|---|---|---|
+| Completion provider | `completion/complete` | Argument autocomplete while a user edits a prompt/template (IDE-style) |
+| Tool | `tools/call` (`ide_completion`) | Model-invoked suggestion lookups |
 
-- **🔤 Code completion** for programming languages and frameworks
-- **⚙️ Command suggestions** for development tools and operations  
-- **📁 File path completion** for common project files
-- **🌍 Environment completion** for deployment contexts and configurations
-- **📦 Tool recommendations** based on project context
+The provider completes the `language` argument of the `code_review` prompt:
+the routing handler matches the request's `ref` against the provider's
+declared reference, prefix-filters, and the framework enforces the spec's
+100-item response cap.
 
-### Why External Data Files?
-
-Unlike hardcoded completion data, this server loads suggestions from **external JSON files** demonstrating:
-- **Maintainability**: Update completion data without code changes
-- **Customization**: Different teams can maintain their own completion databases
-- **Scalability**: Easy to add new languages, frameworks, and tools
-- **Real-world pattern**: How production completion servers manage their data
-
-## Architecture
-
-```
-completion-server/
-├── src/main.rs              # Server implementation
-├── data/                    # External completion data
-│   ├── languages.json       # Programming languages with categories
-│   ├── frameworks.json      # Web frameworks with language mappings  
-│   └── development_commands.json # Commands with tool examples
-└── README.md
-```
-
-## Features
-
-### 🎯 **Context-Aware Completion**
-- Suggests different completions based on parameter names
-- Filters suggestions by current input prefix
-- Provides rich descriptions with categories and examples
-
-### 📊 **Categorized Data**
-- **Programming languages** by category (systems, web, functional, etc.)
-- **Frameworks** by language and type (frontend, backend, fullstack)
-- **Commands** by operation type (build, deploy, monitoring, etc.)
-
-### ⚡ **Production Ready**
-- Loads data from external JSON files at startup
-- Efficient prefix filtering and result limiting
-- Comprehensive error handling and logging
-
-## Running the Server
+## Run
 
 ```bash
-# Ensure you're in the completion-server directory for data/ access
-cd examples/completion-server
-
-# Run the IDE completion server (default: 127.0.0.1:8042)
 cargo run -p completion-server
-
-# Test language completion
-curl -X POST http://127.0.0.1:8042/mcp \
-  -H "Content-Type: application/json" \
-  -d '{
-    "jsonrpc": "2.0",
-    "method": "completion/complete",
-    "params": {
-      "argument": {
-        "name": "language",
-        "value": "ru"
-      },
-      "ref": {}
-    },
-    "id": 1
-  }'
-```
-
-## Completion Categories
-
-### 1. Programming Languages
-
-**Triggered by**: `language`, `lang`, `programming_language`
-
-Suggests programming languages with categories and detailed descriptions loaded from `data/languages.json`.
-
-**Example Response:**
-```json
-{
-  "jsonrpc": "2.0",
-  "result": {
-    "completions": [
-      {
-        "value": "rust",
-        "label": "Rust programming language",
-        "description": "Systems programming language focused on safety and performance (systems)"
-      }
-    ]
-  },
-  "id": 1
-}
-```
-
-### 2. Web Frameworks
-
-**Triggered by**: `framework`, `library`, `lib`
-
-Suggests frameworks with language and category information from `data/frameworks.json`.
-
-**Example Request:**
-```bash
-curl -X POST http://127.0.0.1:8042/mcp \
-  -H "Content-Type: application/json" \
-  -d '{
-    "jsonrpc": "2.0",
-    "method": "completion/complete",
-    "params": {
-      "argument": {
-        "name": "framework",
-        "value": "rea"
-      },
-      "ref": {}
-    },
-    "id": 1
-  }'
+# → http://127.0.0.1:8042/mcp
 ```
 
-**Example Response:**
-```json
-{
-  "jsonrpc": "2.0",
-  "result": {
-    "completions": [
-      {
-        "value": "react",
-        "label": "React framework",
-        "description": "JavaScript library for building user interfaces (javascript - frontend)"
-      }
-    ]
-  },
-  "id": 1
-}
-```
-
-### 3. Development Commands
-
-**Triggered by**: `command`, `cmd`, `action`
-
-Suggests development commands with tool examples from `data/development_commands.json`.
+## Try it (2026-07-28 stateless)
 
-**Example Request:**
 ```bash
-curl -X POST http://127.0.0.1:8042/mcp \
-  -H "Content-Type: application/json" \
-  -d '{
-    "jsonrpc": "2.0",
-    "method": "completion/complete",
-    "params": {
-      "argument": {
-        "name": "command",
-        "value": "bu"
-      },
-      "ref": {}
-    },
-    "id": 1
-  }'
-```
-
-**Example Response:**
-```json
-{
-  "jsonrpc": "2.0",
-  "result": {
-    "completions": [
-      {
-        "value": "build",
-        "label": "Build command",
-        "description": "Compile and build the project - Tools: cargo, npm, gradle, maven, make"
-      }
-    ]
-  },
-  "id": 1
-}
-```
-
-### 4. File Extensions
-
-**Triggered by**: `extension`, `ext`, `file_extension`
-
-Suggests common file extensions with detailed descriptions for different file types.
-
-### 5. File Paths
-
-**Triggered by**: `filename`, `file`, `path`
-
-Suggests common project files like `main.rs`, `README.md`, `Cargo.toml`, `package.json`.
-
-### 6. Semantic Versions
-
-**Triggered by**: `version`
-
-Suggests semantic version patterns: `1.0.0`, `0.1.0`, `2.0.0-beta`.
-
-### 7. Deployment Environments
-
-**Triggered by**: `environment`, `env`
-
-Suggests environment types: `development`, `staging`, `production`.
-
-## External Data Format
-
-### Languages Data (`data/languages.json`)
-```json
-{
-  "programming_languages": [
-    {
-      "name": "rust",
-      "label": "Rust programming language",
-      "description": "Systems programming language focused on safety and performance",
-      "category": "systems"
-    }
-  ]
-}
-```
-
-### Frameworks Data (`data/frameworks.json`)
-```json
-{
-  "web_frameworks": [
-    {
-      "name": "react",
-      "label": "React framework",
-      "description": "JavaScript library for building user interfaces",
-      "category": "frontend",
-      "language": "javascript"
-    }
-  ]
-}
-```
-
-### Commands Data (`data/development_commands.json`)
-```json
-{
-  "development_commands": [
-    {
-      "name": "build",
-      "label": "Build command",
-      "description": "Compile and build the project",
-      "category": "compilation",
-      "common_tools": ["cargo", "npm", "gradle", "maven", "make"]
-    }
-  ]
-}
-```
-
-## Implementation Highlights
-
-### Data Loading
-```rust
-impl IdeCompletionHandler {
-    pub fn new() -> Result<Self, Box<dyn std::error::Error>> {
-        let data_dir = Path::new("data");
-        
-        let languages = Self::load_languages(data_dir)?;
-        let frameworks = Self::load_frameworks(data_dir)?;
-        let commands = Self::load_commands(data_dir)?;
-        
-        Ok(Self { languages, frameworks, commands, file_extensions })
-    }
-}
-```
-
-### Context-Aware Completion
-```rust
-fn get_smart_completions(&self, argument_name: &str, current_value: &str) -> Vec<CompletionSuggestion> {
-    match argument_name.to_lowercase().as_str() {
-        "language" | "lang" | "programming_language" => {
-            self.get_language_completions(&prefix)
-        },
-        "framework" | "library" | "lib" => {
-            self.get_framework_completions(&prefix)
-        },
-        "command" | "cmd" | "action" => {
-            self.get_command_completions(&prefix)
-        },
-        _ => /* fallback suggestions */
-    }
-}
-```
-
-## Real-World Applications
-
-### IDE Integration
-- **VS Code Language Server**: Provide completion for configuration files
-- **IntelliJ Plugin**: Framework and library suggestions
-- **Vim/Neovim LSP**: Command and tool completion
-
-### Development Tools
-- **CLI Tools**: Smart completion for command-line applications
-- **CI/CD Pipelines**: Environment and deployment target completion
-- **Code Generators**: Template and framework selection
-
-### Configuration Management
-- **Docker Compose**: Service and image completion
-- **Kubernetes**: Resource and namespace completion
-- **Terraform**: Provider and resource completion
-
-## Extension Opportunities
-
-### Enhanced Data Sources
-- **Package Registries**: npm, crates.io, PyPI integration
-- **Documentation APIs**: Real-time API completion
-- **Git Repositories**: Branch and tag completion
-- **Cloud Services**: AWS, GCP, Azure resource completion
-
-### Advanced Features
-- **Fuzzy Matching**: More sophisticated search algorithms
-- **Machine Learning**: AI-powered suggestions based on context
-- **User Preferences**: Personalized completion based on usage history
-- **Multi-workspace**: Different completion sets per project type
-
-### Performance Optimizations
-- **Caching**: Cache frequently accessed completion data
-- **Incremental Loading**: Load data on-demand for large datasets
-- **Background Updates**: Refresh completion data without restarts
-
-This completion server demonstrates how external data files enable maintainable, scalable completion systems that can evolve with changing development ecosystems without requiring code changes.
+META='"_meta":{"io.modelcontextprotocol/protocolVersion":"2026-07-28","io.modelcontextprotocol/clientInfo":{"name":"curl","version":"1.0"},"io.modelcontextprotocol/clientCapabilities":{}}'
+
+# Argument completion: "ru" → ["ruby","rust"]
+curl -s -X POST http://127.0.0.1:8042/mcp \
+  -H 'Content-Type: application/json' \
+  -H 'MCP-Protocol-Version: 2026-07-28' \
+  -H 'Mcp-Method: completion/complete' \
+  -d "{\"jsonrpc\":\"2.0\",\"id\":1,\"method\":\"completion/complete\",\"params\":{\"ref\":{\"type\":\"ref/prompt\",\"name\":\"code_review\"},\"argument\":{\"name\":\"language\",\"value\":\"ru\"},$META}}"
+
+# The prompt the completion serves
+curl -s -X POST http://127.0.0.1:8042/mcp \
+  -H 'Content-Type: application/json' \
+  -H 'MCP-Protocol-Version: 2026-07-28' \
+  -H 'Mcp-Method: prompts/get' -H 'Mcp-Name: code_review' \
+  -d "{\"jsonrpc\":\"2.0\",\"id\":2,\"method\":\"prompts/get\",\"params\":{\"name\":\"code_review\",\"arguments\":{\"language\":\"rust\"},$META}}"
+
+# The contrast tool
+curl -s -X POST http://127.0.0.1:8042/mcp \
+  -H 'Content-Type: application/json' \
+  -H 'MCP-Protocol-Version: 2026-07-28' \
+  -H 'Mcp-Method: tools/call' -H 'Mcp-Name: ide_completion' \
+  -d "{\"jsonrpc\":\"2.0\",\"id\":3,\"method\":\"tools/call\",\"params\":{\"name\":\"ide_completion\",\"arguments\":{\"category\":\"language\",\"prefix\":\"py\"},$META}}"
+```
+
+## Contract notes
+
+- A server with completion providers advertises the `completions`
+  capability in `server/discover`; one without answers
+  `completion/complete` with 404 + `-32601`.
+- Malformed params (missing `argument`, unknown `ref` type) → `-32602`.
+- Provider output is capped at 100 values (`total`/`hasMore` reflect a cut).