diff --git a/.github/ISSUE_TEMPLATE/bug_report.md b/.github/ISSUE_TEMPLATE/bug_report.md
new file mode 100644
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--- /dev/null
+++ b/.github/ISSUE_TEMPLATE/bug_report.md
@@ -0,0 +1,59 @@
+---
+name: Bug Report
+about: Report a bug or unexpected behavior
+title: "[BUG] "
+labels: bug
+assignees: ''
+---
+
+## Description
+
+A clear and concise description of the bug.
+
+## To Reproduce
+
+Steps to reproduce the behavior:
+
+1. Create error with '...'
+2. Call method '...'
+3. Observe '...'
+
+## Minimal Reproducible Example
+
+```rust
+use masterror::prelude::*;
+
+fn main() {
+    // Minimal code that reproduces the issue
+}
+```
+
+## Expected Behavior
+
+A clear description of what you expected to happen.
+
+## Actual Behavior
+
+A clear description of what actually happened.
+
+## Error Messages
+
+```
+Paste any error messages, stack traces, or panic output here.
+```
+
+## Environment
+
+- **masterror version**: [e.g., 0.24.19]
+- **Rust version**: [output of `rustc --version`]
+- **Operating System**: [e.g., Linux 5.15, macOS 13.2, Windows 11]
+- **Features enabled**: [e.g., "std", "axum", "sqlx"]
+- **Additional context**: [Any other relevant information]
+
+## Possible Solution
+
+If you have ideas on how to fix the issue, describe them here.
+
+## Additional Context
+
+Add any other context about the problem here (related issues, workarounds, etc.).
diff --git a/.github/ISSUE_TEMPLATE/documentation.md b/.github/ISSUE_TEMPLATE/documentation.md
new file mode 100644
index 0000000..798e7d7
--- /dev/null
+++ b/.github/ISSUE_TEMPLATE/documentation.md
@@ -0,0 +1,58 @@
+---
+name: Documentation Improvement
+about: Suggest improvements to documentation
+title: "[DOCS] "
+labels: documentation
+assignees: ''
+---
+
+## Documentation Issue
+
+**Type**: (check one)
+- [ ] Missing documentation
+- [ ] Incorrect documentation
+- [ ] Unclear documentation
+- [ ] Outdated documentation
+- [ ] Example needed
+
+## Location
+
+**Affected file(s)**:
+- [ ] README.md
+- [ ] CHANGELOG.md
+- [ ] ARCHITECTURE.md
+- [ ] REQUIREMENTS.md
+- [ ] CONTRIBUTING.md
+- [ ] docs.rs API documentation
+- [ ] docs/wiki/
+- [ ] Other: ___________
+
+**Specific section**: (e.g., "Installation" section in README, `AppError::with_field` doc comment)
+
+## Current State
+
+Describe what the current documentation says or what's missing.
+
+```
+Quote the current text here, if applicable.
+```
+
+## Proposed Improvement
+
+Describe what should be changed, added, or clarified.
+
+```
+Provide the proposed text or example here.
+```
+
+## Rationale
+
+Why is this improvement needed? What confusion does it resolve?
+
+## Related Issues
+
+Are there existing issues or PRs related to this documentation?
+
+## Additional Context
+
+Add any other context, screenshots, or examples about the documentation issue here.
diff --git a/.github/ISSUE_TEMPLATE/feature_request.md b/.github/ISSUE_TEMPLATE/feature_request.md
new file mode 100644
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--- /dev/null
+++ b/.github/ISSUE_TEMPLATE/feature_request.md
@@ -0,0 +1,57 @@
+---
+name: Feature Request
+about: Suggest a new feature or enhancement
+title: "[FEATURE] "
+labels: enhancement
+assignees: ''
+---
+
+## Feature Description
+
+A clear and concise description of the feature you'd like to see.
+
+## Use Case
+
+Describe the problem this feature would solve or the workflow it would improve.
+
+**Current behavior**:
+What do you have to do now to accomplish this task?
+
+**Desired behavior**:
+How would this feature make the task easier or better?
+
+## Proposed API (if applicable)
+
+```rust
+// Example of how the feature might be used
+use masterror::prelude::*;
+
+fn example() {
+    // Show the proposed API usage
+}
+```
+
+## Alternatives Considered
+
+Describe alternative solutions or features you've considered.
+
+## Impact Assessment
+
+- **Breaking changes**: Yes / No (describe if yes)
+- **Performance impact**: None / Positive / Negative (explain)
+- **Compatibility**: What versions would this affect?
+- **Dependencies**: Would this require new dependencies?
+
+## Implementation Notes
+
+If you have ideas about how to implement this feature, describe them here.
+
+## Willingness to Contribute
+
+- [ ] I am willing to submit a PR for this feature
+- [ ] I need guidance on implementation
+- [ ] I can only provide requirements/testing
+
+## Additional Context
+
+Add any other context, mockups, or examples about the feature request here.
diff --git a/.github/PULL_REQUEST_TEMPLATE.md b/.github/PULL_REQUEST_TEMPLATE.md
new file mode 100644
index 0000000..c8616d5
--- /dev/null
+++ b/.github/PULL_REQUEST_TEMPLATE.md
@@ -0,0 +1,58 @@
+<!--
+SPDX-FileCopyrightText: 2025 RAprogramm <andrey.rozanov.vl@gmail.com>
+
+SPDX-License-Identifier: MIT
+-->
+
+## Summary
+
+Brief description of what this PR accomplishes.
+
+## Changes
+
+- Added: ...
+- Fixed: ...
+- Changed: ...
+- Removed: ...
+
+## Motivation
+
+Why is this change necessary? What problem does it solve?
+
+## Test Plan
+
+- [ ] Unit tests pass locally (`cargo test --all-features`)
+- [ ] Integration tests pass locally
+- [ ] Doctests compile and run
+- [ ] Benchmarks run without regression (`cargo bench --features benchmarks`)
+- [ ] Code formatted with nightly fmt (`cargo +nightly fmt --all -- --check`)
+- [ ] Clippy passes with no warnings (`cargo clippy --all-targets --all-features -- -D warnings`)
+- [ ] Documentation builds (`cargo doc --no-deps --all-features`)
+- [ ] Manual testing performed (describe if applicable)
+
+## Performance Impact
+
+- [ ] No performance impact
+- [ ] Performance improved (attach benchmark results)
+- [ ] Performance regression justified (explain rationale)
+
+## Breaking Changes
+
+- [ ] No breaking changes
+- [ ] Breaking changes (document migration path in CHANGELOG.md)
+
+## Documentation
+
+- [ ] Updated README.md (if public API changed)
+- [ ] Updated CHANGELOG.md under "Unreleased" section
+- [ ] Added/updated doc comments for public APIs
+- [ ] Added/updated examples (if applicable)
+- [ ] Updated migration guides (if breaking changes)
+
+## Related Issues
+
+Closes #
+
+## Additional Context
+
+Any additional information reviewers should know.
diff --git a/ARCHITECTURE.md b/ARCHITECTURE.md
new file mode 100644
index 0000000..2d9e5ee
--- /dev/null
+++ b/ARCHITECTURE.md
@@ -0,0 +1,699 @@
+<!--
+SPDX-FileCopyrightText: 2025 RAprogramm <andrey.rozanov.vl@gmail.com>
+
+SPDX-License-Identifier: MIT
+-->
+
+# Architecture Documentation
+
+## Table of Contents
+
+1. [High-Level Design](#high-level-design)
+2. [Module Structure](#module-structure)
+3. [Core Types](#core-types)
+4. [Data Flow](#data-flow)
+5. [Extension Points](#extension-points)
+6. [Performance Characteristics](#performance-characteristics)
+7. [Design Patterns](#design-patterns)
+8. [Compile-Time Guarantees](#compile-time-guarantees)
+
+## High-Level Design
+
+### Design Philosophy
+
+This architecture adheres to the [RustManifest](https://github.com/RAprogramm/RustManifest) principles, emphasizing clean code, zero-cost abstractions, comprehensive testing, and professional documentation standards.
+
+masterror follows a **layered architecture** with clear separation between:
+
+1. **Core layer**: Framework-agnostic error types and metadata
+2. **Conversion layer**: Integration with third-party libraries
+3. **Transport layer**: HTTP, gRPC, and serialization adapters
+4. **Derive layer**: Procedural macros for ergonomic derivation
+5. **Turnkey layer**: Opinionated defaults for rapid adoption
+
+```
+┌─────────────────────────────────────────────────────────┐
+│                    Application Code                      │
+└────────────────────────┬────────────────────────────────┘
+                         │
+                         ▼
+┌─────────────────────────────────────────────────────────┐
+│              Turnkey Layer (Optional)                    │
+│  ┌──────────────────────────────────────────────────┐  │
+│  │ Pre-built catalog, classifiers, helper functions │  │
+│  └──────────────────────────────────────────────────┘  │
+└────────────────────────┬────────────────────────────────┘
+                         │
+                         ▼
+┌─────────────────────────────────────────────────────────┐
+│                   Derive Layer                           │
+│  ┌────────────────┬─────────────────┬─────────────┐    │
+│  │ #[derive(Error)]│ #[derive(Master-│ #[provide]  │    │
+│  │                 │      ror)]      │             │    │
+│  └────────────────┴─────────────────┴─────────────┘    │
+└────────────────────────┬────────────────────────────────┘
+                         │
+                         ▼
+┌─────────────────────────────────────────────────────────┐
+│                 Transport Layer                          │
+│  ┌──────────┬───────────┬─────────┬──────────────┐     │
+│  │  Axum    │  Actix    │  Tonic  │  OpenAPI     │     │
+│  │ Responder│ Responder │ Status  │ Schema Gen   │     │
+│  └──────────┴───────────┴─────────┴──────────────┘     │
+└────────────────────────┬────────────────────────────────┘
+                         │
+                         ▼
+┌─────────────────────────────────────────────────────────┐
+│               Conversion Layer                           │
+│  ┌───────┬────────┬───────┬────────┬─────────────┐     │
+│  │ sqlx  │reqwest │ redis │tokio   │ validator   │     │
+│  │       │        │       │        │ ...         │     │
+│  └───────┴────────┴───────┴────────┴─────────────┘     │
+└────────────────────────┬────────────────────────────────┘
+                         │
+                         ▼
+┌─────────────────────────────────────────────────────────┐
+│                    Core Layer                            │
+│  ┌──────────────────────────────────────────────────┐  │
+│  │ AppError │ AppErrorKind │ AppCode │ Metadata     │  │
+│  └──────────────────────────────────────────────────┘  │
+└─────────────────────────────────────────────────────────┘
+```
+
+### Workspace Organization
+
+```
+masterror/
+├── masterror/              # Main crate (re-exports all layers)
+├── masterror-derive/       # Procedural macros
+└── masterror-template/     # Template parser (used by derive)
+```
+
+**Dependency direction**: `masterror` → `masterror-derive` → `masterror-template`
+
+Derive macros expand to code that uses `masterror` public API, creating a build-time dependency cycle handled by Cargo's macro expansion phase.
+
+## Module Structure
+
+### Core Modules
+
+#### `src/lib.rs`
+Entry point, re-exports public API, manages feature flags.
+
+#### `src/app_error/`
+Core error type implementation.
+
+- **`core.rs`**: `AppError` struct definition and `std::error::Error` impl
+- **`constructors.rs`**: Convenience constructors (`AppError::internal`, `::not_found`, etc.)
+- **`metadata.rs`**: `Metadata` and `Field` types for structured context
+- **`context.rs`**: `Context` builder for attaching metadata
+
+#### `src/kind.rs`
+`AppErrorKind` enum mapping to HTTP 4xx/5xx classes and internal categories.
+
+```rust
+pub enum AppErrorKind {
+    BadRequest,      // 400
+    Unauthorized,    // 401
+    Forbidden,       // 403
+    NotFound,        // 404
+    Conflict,        // 409
+    Timeout,         // 408
+    Service,         // 502/503
+    Internal,        // 500
+    // ...
+}
+```
+
+#### `src/code.rs` and `src/code/app_code.rs`
+`AppCode` enum for fine-grained classification (100+ variants).
+
+```rust
+pub enum AppCode {
+    BadRequest,
+    InvalidFormat,
+    MissingField,
+    Unauthorized,
+    TokenExpired,
+    // ...
+}
+```
+
+#### `src/mapping.rs`
+Transport mapping definitions (`HttpMapping`, `GrpcMapping`, `ProblemMapping`).
+
+### Conversion Layer
+
+#### `src/convert/`
+Third-party error conversions via `From` trait impls.
+
+- **`sqlx.rs`**: Database errors → `AppErrorKind::Conflict`, `::Service`, `::Internal`
+- **`reqwest.rs`**: HTTP client errors → `AppErrorKind::Service`, `::Timeout`
+- **`redis.rs`**: Redis errors → `AppErrorKind::Service`, `::Internal`
+- **`tokio.rs`**: Async runtime errors → `AppErrorKind::Internal`, `::Timeout`
+- **`validator.rs`**: Validation errors → `AppErrorKind::BadRequest`
+- **`config.rs`**: Configuration errors → `AppErrorKind::Internal`
+- **`teloxide.rs`**: Telegram bot errors → `AppErrorKind::Service`, `::BadRequest`
+- **`multipart.rs`**: Multipart form errors → `AppErrorKind::BadRequest`
+
+Each conversion:
+1. Maps error variant to `AppErrorKind`
+2. Preserves source error chain
+3. Attaches relevant telemetry (e.g., SQL constraint name, HTTP status code)
+
+### Transport Layer
+
+#### `src/response/`
+HTTP and serialization adapters.
+
+- **`core.rs`**: `ErrorResponse` trait for framework-agnostic responses
+- **`problem_json.rs`**: RFC 7807 Problem Details serialization
+- **`axum_impl.rs`**: `impl IntoResponse for AppError` (Axum)
+- **`actix_impl.rs`**: `impl ResponseError for AppError` (Actix-web)
+- **`mapping.rs`**: HTTP status code and gRPC status mappings
+- **`metadata.rs`**: Metadata serialization with redaction
+
+#### `src/convert/tonic.rs`
+`impl From<AppError> for tonic::Status` with gRPC code mapping.
+
+#### `src/convert/axum.rs` and `src/convert/actix.rs`
+Extended Axum/Actix integrations beyond basic `IntoResponse`.
+
+### Derive Macros
+
+Located in `masterror-derive/src/`:
+
+- **`error_derive.rs`**: `#[derive(Error)]` implementation
+- **`error_trait.rs`**: Trait generation and method synthesis
+- **`masterror_derive.rs`**: `#[derive(Masterror)]` with telemetry and redaction
+- **`provide_derive.rs`**: `#[provide]` for `std::error::Request` providers
+
+### Turnkey Module
+
+#### `src/turnkey/`
+Opinionated defaults for rapid adoption.
+
+- **`domain.rs`**: Pre-built domain error types
+- **`classifier.rs`**: Error classification heuristics
+- **`conversions.rs`**: Automatic conversions with telemetry
+
+### Utility Modules
+
+#### `src/macros.rs`
+`ensure!` and `fail!` macros for control flow.
+
+#### `src/prelude.rs`
+Commonly used types for glob imports.
+
+#### `src/result_ext.rs`
+`ResultExt` trait for ergonomic error context attachment.
+
+#### `src/frontend/`
+WASM/browser compatibility.
+
+- **`browser_console_error.rs`**: `console.error()` integration
+- **`browser_console_ext.rs`**: Trait extensions for browser logging
+
+## Core Types
+
+### `AppError`
+
+```rust
+pub struct AppError {
+    pub kind: AppErrorKind,
+    pub code: AppCode,
+    pub message: String,
+    pub edit_policy: MessageEditPolicy,
+    metadata: Metadata,
+    source: Option<Box<dyn Error + Send + Sync>>,
+    backtrace: Option<Backtrace>,
+    retry_after: Option<RetryAfter>,
+    www_authenticate: Option<String>,
+}
+```
+
+**Invariants**:
+- `kind` and `code` must be semantically consistent (enforced by constructors)
+- `source` chain is immutable after construction
+- `metadata` is append-only (fields can be added but not removed)
+- `message` is either user-facing or internal based on `edit_policy`
+
+### `Metadata`
+
+```rust
+pub struct Metadata {
+    fields: Vec<Field>,
+}
+
+pub enum Field {
+    Str { key: &'static str, value: String, policy: RedactionPolicy },
+    I64 { key: &'static str, value: i64, policy: RedactionPolicy },
+    U64 { key: &'static str, value: u64, policy: RedactionPolicy },
+    F64 { key: &'static str, value: f64, policy: RedactionPolicy },
+    Duration { key: &'static str, value: Duration, policy: RedactionPolicy },
+    IpAddr { key: &'static str, value: IpAddr, policy: RedactionPolicy },
+    Json { key: &'static str, value: Value, policy: RedactionPolicy },
+}
+```
+
+**Invariants**:
+- Keys are static strings (zero allocation overhead)
+- Fields are ordered by insertion
+- Redaction policy is immutable per field
+- No duplicate keys (last insert wins)
+
+### `Context`
+
+Builder for attaching metadata:
+
+```rust
+pub struct Context {
+    kind: AppErrorKind,
+    code: AppCode,
+    message: String,
+    fields: Vec<Field>,
+}
+```
+
+**Usage**:
+```rust
+AppError::internal("db error")
+    .with_field(field::str("table", "users"))
+    .with_field(field::duration("query_time", elapsed))
+```
+
+## Data Flow
+
+### Error Creation Flow
+
+```
+User Code
+  │
+  ├─ AppError::new(kind, message)
+  │    │
+  │    └─> AppError { kind, code: default(kind), message, ... }
+  │
+  └─ AppError::internal(message).with_field(...)
+       │
+       └─> Context::new(kind, message)
+            │
+            └─> Context::with_field(field)
+                 │
+                 └─> Context::into_error()
+                      │
+                      └─> AppError { ..., metadata }
+```
+
+### Third-Party Error Conversion Flow
+
+```
+sqlx::Error
+  │
+  └─ From<sqlx::Error> for AppError
+      │
+      ├─ match error_variant:
+      │   ├─ Database constraint → AppErrorKind::Conflict
+      │   ├─ Connection error → AppErrorKind::Service
+      │   └─ Query error → AppErrorKind::Internal
+      │
+      ├─ Extract metadata (table, constraint, etc.)
+      │
+      └─> AppError {
+            kind: ...,
+            code: ...,
+            message: ...,
+            source: Some(sqlx_error),
+            metadata: [...]
+          }
+```
+
+### HTTP Response Flow
+
+```
+AppError
+  │
+  └─ axum::IntoResponse::into_response()
+      │
+      ├─ ProblemJson::from_app_error()
+      │   │
+      │   ├─ Map kind → HTTP status
+      │   ├─ Serialize metadata (apply redaction)
+      │   └─> RFC 7807 JSON payload
+      │
+      ├─ Build headers
+      │   ├─ Content-Type: application/problem+json
+      │   ├─ Retry-After: ... (if set)
+      │   └─ WWW-Authenticate: ... (if set)
+      │
+      └─> axum::Response
+```
+
+### Derive Macro Expansion Flow
+
+```
+#[derive(Error)]
+#[error("db error: {source}")]
+struct DbError {
+    #[source]
+    source: io::Error,
+}
+
+  │ (proc macro expansion)
+  ▼
+
+impl fmt::Display for DbError {
+    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+        write!(f, "db error: {}", self.source)
+    }
+}
+
+impl std::error::Error for DbError {
+    fn source(&self) -> Option<&(dyn Error + 'static)> {
+        Some(&self.source)
+    }
+}
+```
+
+## Extension Points
+
+### 1. Custom Error Types
+
+Implement `From<CustomError> for AppError`:
+
+```rust
+impl From<MyDomainError> for AppError {
+    fn from(err: MyDomainError) -> Self {
+        match err {
+            MyDomainError::NotFound(id) => {
+                AppError::not_found("resource missing")
+                    .with_field(field::str("resource_id", id))
+            }
+            MyDomainError::InvalidInput(msg) => {
+                AppError::bad_request(msg)
+            }
+        }
+    }
+}
+```
+
+### 2. Custom Metadata Fields
+
+Define domain-specific field builders:
+
+```rust
+pub mod field {
+    pub fn user_id(value: impl Into<String>) -> Field {
+        Field::str_redacted("user_id", value, RedactionPolicy::Hash)
+    }
+
+    pub fn transaction_amount(cents: i64) -> Field {
+        Field::i64("transaction_cents", cents, RedactionPolicy::None)
+    }
+}
+```
+
+### 3. Custom Transport Mappings
+
+Override default mappings via derive attributes:
+
+```rust
+#[derive(Masterror)]
+#[masterror(
+    category = AppErrorKind::Service,
+    map.grpc = 14,  // UNAVAILABLE
+    map.problem = "https://api.example.com/errors/db-unavailable"
+)]
+struct DatabaseUnavailable;
+```
+
+### 4. Custom Redaction Policies
+
+Implement `RedactionPolicy` trait:
+
+```rust
+impl RedactionPolicy {
+    pub fn custom_mask(&self, value: &str) -> String {
+        match self {
+            RedactionPolicy::Custom => mask_pii(value),
+            _ => self.apply_default(value),
+        }
+    }
+}
+```
+
+### 5. Custom Telemetry Providers
+
+Implement `std::error::Request` providers:
+
+```rust
+#[derive(Error)]
+#[error("telemetry snapshot")]
+struct MyError {
+    #[provide(ref = TelemetrySnapshot)]
+    snapshot: TelemetrySnapshot,
+}
+```
+
+## Performance Characteristics
+
+### Allocation Patterns
+
+**Zero-allocation paths**:
+- Error kind/code classification
+- Static message errors (`AppError::internal("static")`)
+- Metadata field key storage (uses `&'static str`)
+
+**Single-allocation paths**:
+- Dynamic message errors (allocates `String`)
+- Metadata field value storage (one allocation per field)
+
+**Multiple-allocation paths**:
+- Source error boxing (unavoidable for trait objects)
+- Backtrace capture (when enabled)
+- RFC 7807 JSON serialization
+
+### Time Complexity
+
+- `AppError::new()`: **O(1)**
+- `with_field()`: **O(1)** amortized (Vec::push)
+- `From<ThirdPartyError>`: **O(1)** to **O(k)** where k = number of fields attached
+- `ProblemJson::from_app_error()`: **O(n)** where n = number of metadata fields
+- HTTP response generation: **O(n)** for serialization
+
+### Memory Layout
+
+```
+AppError: 120 bytes (on x86_64)
+├─ kind: 1 byte (enum discriminant)
+├─ code: 2 bytes (enum discriminant)
+├─ message: 24 bytes (String)
+├─ edit_policy: 1 byte (enum discriminant)
+├─ metadata: 24 bytes (Vec<Field>)
+├─ source: 16 bytes (Option<Box<...>>)
+├─ backtrace: 16 bytes (Option<Backtrace>)
+├─ retry_after: 16 bytes (Option<RetryAfter>)
+└─ www_authenticate: 24 bytes (Option<String>)
+```
+
+Field: 40-48 bytes depending on variant (unoptimized enum layout).
+
+### Benchmark Results
+
+Typical performance on modern x86_64 CPU:
+
+- **Error creation with metadata**: ~50-100ns
+- **Context into_error conversion**: ~80-150ns
+- **ProblemJson serialization**: ~300-500ns
+- **Full HTTP response generation**: ~800-1200ns
+
+Regressions >10% from these baselines fail CI.
+
+## Design Patterns
+
+### 1. Builder Pattern
+
+`Context` and `AppError` fluent APIs:
+
+```rust
+AppError::internal("db error")
+    .with_field(field::str("table", "users"))
+    .with_retry_after_duration(Duration::from_secs(30))
+```
+
+### 2. Strategy Pattern
+
+Redaction policies encapsulate field masking strategies:
+
+```rust
+enum RedactionPolicy {
+    None,
+    Redact,
+    Hash,
+    Last4,
+}
+```
+
+### 3. Adapter Pattern
+
+Transport layers adapt `AppError` to framework-specific types:
+
+```rust
+impl IntoResponse for AppError {
+    fn into_response(self) -> Response {
+        // Adapt to Axum's Response type
+    }
+}
+```
+
+### 4. Type-State Pattern
+
+`Context` ensures errors are constructed correctly before conversion:
+
+```rust
+Context::new(kind, message)  // Incomplete state
+    .with_field(field)        // Still building
+    .into_error()             // Transition to complete state
+```
+
+### 5. Extension Trait Pattern
+
+`ResultExt` adds methods to standard `Result`:
+
+```rust
+pub trait ResultExt<T, E> {
+    fn with_context<F>(self, f: F) -> Result<T, AppError>
+    where
+        F: FnOnce(E) -> AppError;
+}
+```
+
+### 6. Derive Macro Pattern
+
+Procedural macros generate boilerplate implementations:
+
+```rust
+#[derive(Error)]  // Generates Display, Error, From impls
+```
+
+## Compile-Time Guarantees
+
+### 1. No Unsafe Code
+
+Enforced by:
+```toml
+[lints.rust]
+unsafe_code = "forbid"
+```
+
+### 2. Type Safety
+
+- Error kinds are enum variants (no string matching)
+- Metadata fields are strongly typed (no `HashMap<String, String>`)
+- Source errors preserve type information via trait objects
+
+### 3. Send + Sync Bounds
+
+All errors implement `Send + Sync` for concurrent usage:
+
+```rust
+impl Error for AppError + Send + Sync + 'static
+```
+
+### 4. No Panics in Library Code
+
+Enforced by code review and testing. Only `unreachable!()` after exhaustive matches.
+
+### 5. Feature Flag Isolation
+
+Feature combinations tested in CI via matrix:
+
+```yaml
+features: [
+  ["std"],
+  ["std", "axum"],
+  ["std", "actix"],
+  ["std", "turnkey"],
+  ["std", "axum", "sqlx", "tracing"],
+]
+```
+
+### 6. MSRV Guarantees
+
+CI tests on MSRV (1.90) and stable to prevent accidental newer Rust usage.
+
+## Deployment Considerations
+
+### Feature Flag Selection
+
+**Minimal setup** (library use):
+```toml
+masterror = { version = "0.24", default-features = false }
+```
+
+**HTTP service**:
+```toml
+masterror = { version = "0.24", features = ["std", "axum", "tracing"] }
+```
+
+**Full-stack service**:
+```toml
+masterror = { version = "0.24", features = [
+    "std", "axum", "sqlx", "reqwest", "redis",
+    "tracing", "metrics", "backtrace"
+] }
+```
+
+**Rapid prototype**:
+```toml
+masterror = { version = "0.24", features = ["turnkey"] }
+```
+
+### Error Budget
+
+Typical error overhead per request:
+- **CPU**: 100-200ns error creation + 500-1000ns serialization
+- **Memory**: 120 bytes base + 40 bytes per metadata field
+- **Allocations**: 1-3 allocations per error (depending on metadata)
+
+For high-throughput services (>100k req/s), consider:
+- Reusing error instances via thread-local storage
+- Limiting metadata fields to <5 per error
+- Disabling backtrace capture in production
+
+### Observability Integration
+
+**Tracing**:
+```rust
+#[instrument(err)]
+fn operation() -> Result<T, AppError> {
+    // Errors automatically logged with span context
+}
+```
+
+**Metrics**:
+```rust
+let counter = error_counter(err.kind, err.code);
+counter.increment(1);
+```
+
+## Future Architecture Evolution
+
+### Planned Enhancements
+
+1. **Async context propagation**: Store metadata in tokio task-local storage
+2. **OpenTelemetry native**: Directly export errors as OTel events
+3. **Error aggregation**: Batch errors for distributed tracing
+4. **Recovery strategies**: Optional retry/fallback builders
+
+### Stability Guarantees
+
+- **Core types**: Stable, semver-compatible
+- **Transport adapters**: Semver-minor for new adapters
+- **Derive macros**: Syntax is stable, expansion may improve
+- **Turnkey module**: May evolve with breaking changes (opt-in)
+
+### Deprecation Policy
+
+- Deprecated features remain for 2 minor versions
+- Migration guides provided in CHANGELOG
+- Compiler warnings guide users to replacements
diff --git a/CODE_OF_CONDUCT.md b/CODE_OF_CONDUCT.md
new file mode 100644
index 0000000..d940e0a
--- /dev/null
+++ b/CODE_OF_CONDUCT.md
@@ -0,0 +1,135 @@
+<!--
+SPDX-FileCopyrightText: 2025 RAprogramm <andrey.rozanov.vl@gmail.com>
+
+SPDX-License-Identifier: MIT
+-->
+
+# Contributor Covenant Code of Conduct
+
+## Our Pledge
+
+We as members, contributors, and leaders pledge to make participation in our
+community a harassment-free experience for everyone, regardless of age, body
+size, visible or invisible disability, ethnicity, sex characteristics, gender
+identity and expression, level of experience, education, socio-economic status,
+nationality, personal appearance, race, religion, or sexual identity
+and orientation.
+
+We pledge to act and interact in ways that contribute to an open, welcoming,
+diverse, inclusive, and healthy community.
+
+## Our Standards
+
+Examples of behavior that contributes to a positive environment for our
+community include:
+
+* Demonstrating empathy and kindness toward other people
+* Being respectful of differing opinions, viewpoints, and experiences
+* Giving and gracefully accepting constructive feedback
+* Accepting responsibility and apologizing to those affected by our mistakes,
+  and learning from the experience
+* Focusing on what is best not just for us as individuals, but for the
+  overall community
+
+Examples of unacceptable behavior include:
+
+* The use of sexualized language or imagery, and sexual attention or
+  advances of any kind
+* Trolling, insulting or derogatory comments, and personal or political attacks
+* Public or private harassment
+* Publishing others' private information, such as a physical or email
+  address, without their explicit permission
+* Other conduct which could reasonably be considered inappropriate in a
+  professional setting
+
+## Enforcement Responsibilities
+
+Project maintainers are responsible for clarifying and enforcing our standards of
+acceptable behavior and will take appropriate and fair corrective action in
+response to any behavior that they deem inappropriate, threatening, offensive,
+or harmful.
+
+Project maintainers have the right and responsibility to remove, edit, or reject
+comments, commits, code, wiki edits, issues, and other contributions that are
+not aligned to this Code of Conduct, and will communicate reasons for moderation
+decisions when appropriate.
+
+## Scope
+
+This Code of Conduct applies within all community spaces, and also applies when
+an individual is officially representing the community in public spaces.
+Examples of representing our community include using an official e-mail address,
+posting via an official social media account, or acting as an appointed
+representative at an online or offline event.
+
+## Enforcement
+
+Instances of abusive, harassing, or otherwise unacceptable behavior may be
+reported to the project maintainers responsible for enforcement at
+andrey.rozanov.vl@gmail.com.
+
+All complaints will be reviewed and investigated promptly and fairly.
+
+All project maintainers are obligated to respect the privacy and security of the
+reporter of any incident.
+
+## Enforcement Guidelines
+
+Project maintainers will follow these Community Impact Guidelines in determining
+the consequences for any action they deem in violation of this Code of Conduct:
+
+### 1. Correction
+
+**Community Impact**: Use of inappropriate language or other behavior deemed
+unprofessional or unwelcome in the community.
+
+**Consequence**: A private, written warning from project maintainers, providing
+clarity around the nature of the violation and an explanation of why the
+behavior was inappropriate. A public apology may be requested.
+
+### 2. Warning
+
+**Community Impact**: A violation through a single incident or series
+of actions.
+
+**Consequence**: A warning with consequences for continued behavior. No
+interaction with the people involved, including unsolicited interaction with
+those enforcing the Code of Conduct, for a specified period of time. This
+includes avoiding interactions in community spaces as well as external channels
+like social media. Violating these terms may lead to a temporary or
+permanent ban.
+
+### 3. Temporary Ban
+
+**Community Impact**: A serious violation of community standards, including
+sustained inappropriate behavior.
+
+**Consequence**: A temporary ban from any sort of interaction or public
+communication with the community for a specified period of time. No public or
+private interaction with the people involved, including unsolicited interaction
+with those enforcing the Code of Conduct, is allowed during this period.
+Violating these terms may lead to a permanent ban.
+
+### 4. Permanent Ban
+
+**Community Impact**: Demonstrating a pattern of violation of community
+standards, including sustained inappropriate behavior, harassment of an
+individual, or aggression toward or disparagement of classes of individuals.
+
+**Consequence**: A permanent ban from any sort of public interaction within
+the community.
+
+## Attribution
+
+This Code of Conduct is adapted from the [Contributor Covenant][homepage],
+version 2.0, available at
+https://www.contributor-covenant.org/version/2/0/code_of_conduct.html.
+
+Community Impact Guidelines were inspired by [Mozilla's code of conduct
+enforcement ladder](https://github.com/mozilla/diversity).
+
+[homepage]: https://www.contributor-covenant.org
+
+For answers to common questions about this code of conduct, see the FAQ at
+https://www.contributor-covenant.org/faq. Translations are available at
+https://www.contributor-covenant.org/translations.
diff --git a/CONTRIBUTING.md b/CONTRIBUTING.md
new file mode 100644
index 0000000..2d030d6
--- /dev/null
+++ b/CONTRIBUTING.md
@@ -0,0 +1,519 @@
+<!--
+SPDX-FileCopyrightText: 2025 RAprogramm <andrey.rozanov.vl@gmail.com>
+
+SPDX-License-Identifier: MIT
+-->
+
+# Contributing to masterror
+
+Thank you for considering contributing to masterror. This document outlines the development process, coding standards, and quality requirements.
+
+## Table of Contents
+
+1. [Getting Started](#getting-started)
+2. [Development Environment](#development-environment)
+3. [Coding Standards](#coding-standards)
+4. [Testing Requirements](#testing-requirements)
+5. [Pull Request Process](#pull-request-process)
+6. [Commit Message Format](#commit-message-format)
+7. [Code Review Guidelines](#code-review-guidelines)
+8. [Performance Benchmarking](#performance-benchmarking)
+9. [Documentation Standards](#documentation-standards)
+10. [Issue Reporting](#issue-reporting)
+
+## Getting Started
+
+### Prerequisites
+
+- **Rust**: MSRV 1.90 (stable and nightly toolchains recommended)
+- **Tools**: `cargo-audit`, `cargo-deny`, `cargo-tarpaulin` or `cargo-llvm-cov` (for coverage)
+- **GitHub CLI**: `gh` (optional but recommended for workflow management)
+
+### Initial Setup
+
+```bash
+git clone https://github.com/RAprogramm/masterror.git
+cd masterror
+
+rustup toolchain install stable nightly
+rustup component add clippy rustfmt --toolchain nightly
+
+cargo build --all-features
+cargo test --all-features
+```
+
+### Workspace Structure
+
+```
+masterror/
+├── src/                    # Core library
+├── masterror-derive/       # Procedural macros
+├── masterror-template/     # Template parser
+├── tests/                  # Integration tests
+├── benches/                # Criterion benchmarks
+├── examples/               # Usage examples
+├── docs/                   # Extended documentation
+└── .github/                # CI/CD workflows
+```
+
+## Development Environment
+
+### Editor Configuration
+
+Configure your editor to:
+- Use 4 spaces for indentation
+- Maximum line length: 99 characters
+- Trim trailing whitespace
+- Insert final newline
+
+### Recommended Extensions
+
+**VS Code**:
+- rust-analyzer
+- Even Better TOML
+- crates
+
+**IntelliJ IDEA**:
+- Rust plugin
+
+## Coding Standards
+
+This project adheres to the [RustManifest](https://github.com/RAprogramm/RustManifest) guidelines, which define comprehensive standards for professional Rust development.
+
+### Style Guide
+
+We follow Rust standard formatting with project-specific overrides in `.rustfmt.toml` based on [RustManifest .rustfmt.toml reference](https://github.com/RAprogramm/RustManifest/blob/main/.rustfmt.toml):
+
+```bash
+cargo +nightly fmt --all
+```
+
+**Key principles**:
+- Line limit: 99 characters
+- Imports: grouped (std, external, internal)
+- No `::` operator except in `use` statements
+- Avoid `unwrap()` and `expect()` in library code (tests are exempt)
+- Minimize `clone()` usage
+- Meaningful variable names; constants in `SCREAMING_SNAKE_CASE`
+
+### Documentation Requirements
+
+Every public item SHALL have:
+
+1. **Summary**: One-line description
+2. **Details**: Behavior explanation
+3. **Parameters**: Document all parameters
+4. **Return value**: Document return semantics
+5. **Errors**: Document error conditions
+6. **Examples**: At least one doctest
+7. **Safety**: Document unsafe code (if any)
+
+Example:
+
+```rust
+/// Converts a domain error into an application error with telemetry.
+///
+/// This function attaches structured metadata fields to the error context,
+/// applies the specified redaction policy, and maps the error kind to the
+/// appropriate transport-level representation.
+///
+/// # Parameters
+///
+/// - `source`: The source error to convert
+/// - `metadata`: Structured telemetry fields to attach
+///
+/// # Returns
+///
+/// Returns an `AppError` with the source error, metadata, and appropriate
+/// error kind classification.
+///
+/// # Examples
+///
+/// ```
+/// use masterror::{AppError, field};
+///
+/// let err = AppError::internal("db connection lost")
+///     .with_field(field::str("table", "users"));
+/// assert_eq!(err.metadata().len(), 1);
+/// ```
+pub fn with_field(self, field: Field) -> Self {
+    // implementation
+}
+```
+
+### Error Handling
+
+- All fallible operations return `Result<T, E>`
+- Use `masterror::AppError` for application-level errors
+- Preserve error source chains
+- Attach relevant context via metadata
+- No panics except in tests and `unreachable!()` after exhaustive matches
+
+### Type System Usage
+
+- Prefer `&str` over `String` when ownership is not required
+- Use `&[T]` instead of `&Vec<T>` in function parameters
+- Use `Vec::with_capacity()` when size is known
+- Avoid unnecessary trait bounds on struct definitions
+
+## Testing Requirements
+
+### Coverage Target
+
+Minimum: **95%** | Target: **100%**
+
+### Test Categories
+
+#### 1. Unit Tests
+
+Located in `#[cfg(test)] mod tests` blocks within source files.
+
+```rust
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn error_creation_attaches_metadata() {
+        let err = AppError::internal("test")
+            .with_field(field::str("key", "value"));
+        assert_eq!(err.metadata().len(), 1);
+    }
+
+    #[test]
+    fn invalid_input_returns_bad_request() {
+        let result = validate_input("");
+        assert!(matches!(
+            result.unwrap_err().kind,
+            AppErrorKind::BadRequest
+        ));
+    }
+}
+```
+
+#### 2. Integration Tests
+
+Located in `tests/` directory.
+
+```rust
+use masterror::prelude::*;
+
+#[test]
+fn axum_integration_converts_app_error_to_response() {
+    let err = AppError::not_found("resource missing");
+    let response = axum::response::IntoResponse::into_response(err);
+    assert_eq!(response.status(), StatusCode::NOT_FOUND);
+}
+```
+
+#### 3. Doctests
+
+Every public API example SHALL compile and run:
+
+```rust
+/// ```
+/// use masterror::AppError;
+/// let err = AppError::unauthorized("token expired");
+/// assert_eq!(err.kind, masterror::AppErrorKind::Unauthorized);
+/// ```
+```
+
+### Test Principles
+
+1. **Deterministic**: No time, network, or environment dependencies
+2. **Isolated**: Tests do not share mutable state
+3. **Fast**: Unit tests complete in milliseconds
+4. **Comprehensive**: Cover happy paths, error paths, edge cases
+
+### Error Path Testing
+
+Every error variant SHALL be tested:
+
+```rust
+#[test]
+fn constraint_violation_maps_to_conflict() {
+    let db_err = simulate_unique_violation();
+    let app_err: AppError = db_err.into();
+    assert!(matches!(app_err.kind, AppErrorKind::Conflict));
+}
+```
+
+### Running Tests
+
+```bash
+cargo test --all-features
+cargo test --no-default-features
+cargo test --test integration_http
+cargo test --doc
+
+MIRIFLAGS="-Zmiri-strict-provenance" cargo +nightly miri test
+```
+
+## Pull Request Process
+
+### 1. Create Issue First
+
+Before implementing features or fixes:
+
+1. Search existing issues to avoid duplicates
+2. Create issue describing problem/feature
+3. Wait for maintainer acknowledgment (for large changes)
+
+### 2. Branch Naming
+
+Branch name SHALL be the issue number without prefixes:
+
+```bash
+git checkout -b 123
+```
+
+### 3. Implementation
+
+Make changes following coding standards. Commit frequently with descriptive messages.
+
+### 4. Pre-PR Checklist
+
+Before submitting, verify:
+
+```bash
+cargo +nightly fmt --all --check
+cargo clippy --all-targets --all-features -- -D warnings
+cargo test --all-features
+cargo bench --no-run --features benchmarks
+cargo doc --no-deps --all-features
+```
+
+### 5. Cancel Previous Workflows
+
+Before pushing, cancel in-progress workflows to save CI resources:
+
+```bash
+gh run list --branch $(git branch --show-current) --status in_progress \
+    --json databaseId --jq '.[].databaseId' | xargs -I {} gh run cancel {}
+```
+
+### 6. Push and Create PR
+
+```bash
+git push -u origin 123
+gh pr create --title "123" --body "$(cat <<'EOF'
+## Summary
+
+Brief description of changes.
+
+## Changes
+
+- Added X
+- Fixed Y
+- Updated Z
+
+## Test Plan
+
+- [ ] Unit tests pass
+- [ ] Integration tests pass
+- [ ] Benchmarks show no regression
+- [ ] Documentation updated
+
+Closes #123
+EOF
+)"
+```
+
+### 7. PR Review
+
+- Respond to feedback promptly
+- Push additional commits to address comments
+- Request re-review after changes
+- Do not force-push after initial review
+
+### 8. Merge
+
+Maintainers will merge after:
+- All CI checks pass
+- At least one approval
+- No unresolved conversations
+
+## Commit Message Format
+
+```
+#<issue> <type>: <description>
+
+[optional body]
+
+[optional footer]
+```
+
+### Types
+
+- `feat`: New feature
+- `fix`: Bug fix
+- `perf`: Performance improvement
+- `refactor`: Code restructuring without behavior change
+- `test`: Adding or updating tests
+- `docs`: Documentation changes
+- `ci`: CI/CD changes
+- `chore`: Maintenance tasks
+
+### Examples
+
+```
+#42 feat: add async handler support
+
+Implements async error handlers for Axum and Actix-web frameworks.
+Handlers can now return async closures that resolve to AppError.
+
+#89 fix: correct gRPC status mapping for timeout errors
+
+Previously mapped to UNAVAILABLE, now correctly maps to DEADLINE_EXCEEDED
+per gRPC specification.
+
+#120 perf: optimize metadata serialization path
+
+Reduces allocations in ProblemJson conversion by 40%.
+Benchmark results show 200ns improvement on average.
+```
+
+## Code Review Guidelines
+
+### For Contributors
+
+- Keep PRs focused (one issue per PR)
+- Respond to feedback within 48 hours
+- Accept constructive criticism professionally
+- Ask questions if feedback is unclear
+
+### For Reviewers
+
+Review for:
+1. **Correctness**: Does it solve the problem?
+2. **Testing**: Adequate test coverage?
+3. **Performance**: Any obvious inefficiencies?
+4. **Documentation**: Public APIs documented?
+5. **Style**: Follows project conventions?
+6. **Safety**: No unsafe code without justification?
+
+Use these labels:
+- "looks good to me" (LGTM): Approve
+- "request changes": Blocking issues
+- "comment": Non-blocking suggestions
+
+## Performance Benchmarking
+
+### Running Benchmarks
+
+```bash
+cargo bench --features benchmarks --bench error_paths
+cargo bench --features benchmarks --bench error_paths -- --save-baseline main
+```
+
+### Adding Benchmarks
+
+Place criterion benchmarks in `benches/`:
+
+```rust
+use criterion::{black_box, criterion_group, criterion_main, Criterion};
+use masterror::AppError;
+
+fn benchmark_error_creation(c: &mut Criterion) {
+    c.bench_function("create_error_with_metadata", |b| {
+        b.iter(|| {
+            black_box(AppError::internal("test")
+                .with_field(field::str("key", "value")))
+        });
+    });
+}
+
+criterion_group!(benches, benchmark_error_creation);
+criterion_main!(benches);
+```
+
+### Regression Policy
+
+CI will fail if benchmarks show >10% performance regression. If regression is necessary:
+1. Document rationale in PR description
+2. Add `[perf-regression-justified]` label
+3. Require maintainer approval
+
+## Documentation Standards
+
+### README Updates
+
+Update README.md when adding:
+- New features requiring examples
+- Breaking changes requiring migration
+- New feature flags
+
+### CHANGELOG
+
+Add entries to CHANGELOG.md under "Unreleased" section:
+
+```markdown
+## [Unreleased]
+
+### Added
+- Support for async error handlers (#42)
+
+### Fixed
+- Incorrect gRPC status mapping for timeouts (#89)
+
+### Changed
+- BREAKING: Renamed `ErrorContext` to `Context` (#105)
+
+### Performance
+- Reduced metadata serialization allocations by 40% (#120)
+```
+
+### Wiki and Guides
+
+Extended documentation goes in `docs/wiki/`:
+- Step-by-step tutorials
+- Migration guides
+- Comparison with alternatives
+- Troubleshooting recipes
+
+## Issue Reporting
+
+### Bug Reports
+
+Use the bug report template and include:
+1. Minimal reproducible example
+2. Expected vs actual behavior
+3. Environment (Rust version, OS, features enabled)
+4. Error messages and stack traces
+
+### Feature Requests
+
+Use the feature request template and include:
+1. Use case description
+2. Proposed API (if applicable)
+3. Alternatives considered
+4. Impact assessment
+
+### Questions
+
+For usage questions:
+1. Check existing documentation and issues first
+2. Use GitHub Discussions (if enabled) or issues
+3. Provide context and code samples
+
+## Release Process
+
+(For maintainers)
+
+1. Update CHANGELOG.md with version number and date
+2. Update version in all `Cargo.toml` files
+3. Run full CI locally
+4. Create git tag: `git tag -a v0.x.y -m "Release v0.x.y"`
+5. Push tag: `git push origin v0.x.y`
+6. GitHub Actions will publish to crates.io
+7. Create GitHub release with CHANGELOG excerpt
+
+## Getting Help
+
+- **Documentation**: https://docs.rs/masterror
+- **Issues**: https://github.com/RAprogramm/masterror/issues
+- **Email**: andrey.rozanov.vl@gmail.com
+
+## License
+
+By contributing, you agree that your contributions will be dual-licensed under MIT OR Apache-2.0.
diff --git a/README.md b/README.md
index 46881af..4ac06c9 100644
--- a/README.md
+++ b/README.md
@@ -477,6 +477,7 @@ assert_eq!(problem.grpc.expect("grpc").name, "UNAUTHENTICATED");
 - Browse the [crate documentation on docs.rs](https://docs.rs/masterror) for API
   details, feature-specific guides and transport tables.
 - Check [`CHANGELOG.md`](CHANGELOG.md) for release highlights and migration notes.
+- Review [RustManifest](https://github.com/RAprogramm/RustManifest) for the development standards and best practices this project follows.
 
 ---
 
diff --git a/README.template.md b/README.template.md
index e4881ca..44b149f 100644
--- a/README.template.md
+++ b/README.template.md
@@ -472,6 +472,7 @@ assert_eq!(problem.grpc.expect("grpc").name, "UNAUTHENTICATED");
 - Browse the [crate documentation on docs.rs](https://docs.rs/masterror) for API
   details, feature-specific guides and transport tables.
 - Check [`CHANGELOG.md`](CHANGELOG.md) for release highlights and migration notes.
+- Review [RustManifest](https://github.com/RAprogramm/RustManifest) for the development standards and best practices this project follows.
 
 ---
 
diff --git a/REQUIREMENTS.md b/REQUIREMENTS.md
new file mode 100644
index 0000000..fc67723
--- /dev/null
+++ b/REQUIREMENTS.md
@@ -0,0 +1,421 @@
+<!--
+SPDX-FileCopyrightText: 2025 RAprogramm <andrey.rozanov.vl@gmail.com>
+
+SPDX-License-Identifier: MIT
+-->
+
+# Requirements Specification
+
+> This specification follows the [RustManifest](https://github.com/RAprogramm/RustManifest) development standards, which define professional guidelines for Rust project structure, code quality, testing, and documentation.
+
+## 1. Problem Statement
+
+### 1.1 Context
+
+Modern Rust services require consistent, observable error handling across multiple transport layers (HTTP, gRPC, WebAssembly) and integration boundaries (databases, HTTP clients, message queues). Existing error handling libraries present several challenges:
+
+1. **Fragmentation**: `thiserror` provides derives but lacks transport mappings; `anyhow` offers dynamic errors but loses type safety; combining both creates inconsistent error surfaces.
+
+2. **Transport overhead**: Mapping domain errors to HTTP status codes, gRPC status values, and RFC 7807 Problem Details requires repetitive glue code in every service.
+
+3. **Telemetry gaps**: Structured error context (request IDs, user IDs, operation metadata) is typically stored as strings in ad-hoc maps, losing type safety and making redaction policies difficult to enforce.
+
+4. **Integration burden**: Each third-party library error (sqlx, reqwest, redis) needs manual conversion logic, source chain preservation, and context attachment.
+
+5. **Framework coupling**: Error types often become tightly coupled to web frameworks (Actix, Axum), making code reuse across projects difficult.
+
+### 1.2 Target Users
+
+1. **Backend service developers** building microservices with multiple transport protocols
+2. **Library authors** requiring framework-agnostic error types with rich context
+3. **Platform teams** establishing error handling standards across service fleets
+4. **WebAssembly developers** needing browser-compatible error reporting without heap allocation requirements
+
+### 1.3 Goals
+
+1. Provide a unified error taxonomy that maps cleanly to HTTP, gRPC, and RFC 7807 Problem Details
+2. Offer typed, structured telemetry with field-level redaction controls
+3. Enable framework-agnostic error handling with optional transport adapters
+4. Deliver zero-cost abstractions with no unsafe code
+5. Maintain comprehensive test coverage and documentation
+
+### 1.4 Non-Goals
+
+1. Replace all uses of `thiserror` or `anyhow` in existing codebases (compatibility is preferred)
+2. Provide dynamic error type erasure by default (users can opt into this via features)
+3. Offer automatic error recovery or retry logic (this is application-specific)
+4. Support runtime error message localization (compile-time message selection is possible)
+
+## 2. Use Cases
+
+### 2.1 UC-001: HTTP Service Error Handling
+
+**Actor**: Backend service developer
+**Precondition**: Service uses Axum or Actix-web
+**Trigger**: Business logic returns domain error
+**Main Flow**:
+1. Domain function returns `Result<T, DomainError>`
+2. `DomainError` implements `From<DomainError> for AppError`
+3. Framework automatically converts `AppError` to HTTP response
+4. Client receives RFC 7807 Problem Details with appropriate status code
+
+**Postcondition**: Error is logged with structured telemetry, client receives consistent error format
+
+**Alternative Flows**:
+- A1: If error contains sensitive data, redaction policy masks fields before serialization
+- A2: If retry hint is set, `Retry-After` header is included in response
+
+### 2.2 UC-002: gRPC Status Mapping
+
+**Actor**: gRPC service developer
+**Precondition**: Service uses Tonic
+**Trigger**: Business logic returns domain error
+**Main Flow**:
+1. Domain function returns `Result<T, DomainError>`
+2. `DomainError` defines gRPC status code mapping via derive macro
+3. Error is converted to `tonic::Status` with message and details
+4. gRPC client receives status with structured metadata
+
+**Postcondition**: Error maintains consistent mapping between HTTP and gRPC transports
+
+### 2.3 UC-003: Database Error Integration
+
+**Actor**: Service using sqlx
+**Precondition**: Database query fails
+**Trigger**: sqlx returns `sqlx::Error`
+**Main Flow**:
+1. sqlx operation returns error
+2. `From<sqlx::Error> for AppError` converts error with telemetry
+3. Constraint violations map to `AppErrorKind::Conflict`
+4. Connection errors map to `AppErrorKind::Service`
+5. Query-specific metadata (table name, operation) is attached
+
+**Postcondition**: Database errors are consistently classified and observable
+
+### 2.4 UC-004: Structured Telemetry Attachment
+
+**Actor**: Developer instrumenting error paths
+**Precondition**: Operation has contextual metadata
+**Trigger**: Error occurs during operation
+**Main Flow**:
+1. Developer creates error with metadata builders
+2. Metadata includes typed fields (strings, integers, durations, IPs)
+3. Fields have individual redaction policies (hash, last4, redact, none)
+4. Error propagates through call stack preserving metadata
+5. Telemetry backend receives structured fields
+
+**Postcondition**: Errors are observable without string concatenation or manual JSON building
+
+### 2.5 UC-005: Custom Domain Error Derivation
+
+**Actor**: Library author defining domain errors
+**Precondition**: Domain has specific error taxonomy
+**Trigger**: Need to integrate domain errors with masterror
+**Main Flow**:
+1. Define domain error enum with variants
+2. Apply `#[derive(Error, Masterror)]` with per-variant mappings
+3. Specify `AppCode`, `AppErrorKind`, telemetry, and redaction per variant
+4. Framework automatically converts to HTTP/gRPC responses
+5. Source errors and backtraces are preserved
+
+**Postcondition**: Domain errors integrate seamlessly without manual glue code
+
+## 3. Functional Requirements
+
+### 3.1 Core Error Types
+
+**FR-001**: System SHALL provide `AppError` type with kind, code, message, metadata, and source
+**FR-002**: System SHALL provide `AppErrorKind` enum covering HTTP 4xx/5xx status classes
+**FR-003**: System SHALL provide `AppCode` enum for fine-grained error classification
+**FR-004**: System SHALL support error source chaining via `std::error::Error`
+**FR-005**: System SHALL support backtrace capture when enabled
+
+### 3.2 Metadata System
+
+**FR-006**: System SHALL support typed metadata fields (string, i64, u64, f64, Duration, IpAddr, JSON)
+**FR-007**: System SHALL provide field-level redaction policies (none, hash, last4, redact)
+**FR-008**: System SHALL provide builders for common field types
+**FR-009**: System SHALL allow metadata attachment at error creation time
+**FR-010**: System SHALL preserve metadata through error conversions
+
+### 3.3 Derive Macros
+
+**FR-011**: System SHALL provide `#[derive(Error)]` compatible with thiserror syntax
+**FR-012**: System SHALL provide `#[derive(Masterror)]` for full integration
+**FR-013**: System SHALL support per-variant mappings in enum errors
+**FR-014**: System SHALL generate `From` implementations for source errors
+**FR-015**: System SHALL support telemetry attachment via derive attributes
+
+### 3.4 Transport Mappings
+
+**FR-016**: System SHALL map `AppErrorKind` to HTTP status codes
+**FR-017**: System SHALL map `AppErrorKind` to gRPC status codes
+**FR-018**: System SHALL generate RFC 7807 Problem Details JSON
+**FR-019**: System SHALL support custom Problem type URIs
+**FR-020**: System SHALL include retry hints in HTTP headers when specified
+
+### 3.5 Integrations
+
+**FR-021**: System SHALL provide `From` implementations for sqlx errors
+**FR-022**: System SHALL provide `From` implementations for reqwest errors
+**FR-023**: System SHALL provide `From` implementations for redis errors
+**FR-024**: System SHALL provide `From` implementations for validator errors
+**FR-025**: System SHALL provide `From` implementations for config errors
+**FR-026**: System SHALL provide `From` implementations for tokio errors
+**FR-027**: System SHALL provide `From` implementations for teloxide errors
+**FR-028**: System SHALL provide `From` implementations for multipart errors
+
+### 3.6 Feature Flags
+
+**FR-029**: System SHALL compile with no default features enabled
+**FR-030**: System SHALL provide opt-in features for each integration
+**FR-031**: System SHALL provide opt-in features for each transport
+**FR-032**: System SHALL provide opt-in features for telemetry backends
+**FR-033**: System SHALL provide turnkey feature with opinionated defaults
+
+### 3.7 Documentation
+
+**FR-034**: System SHALL document all public types with doc comments
+**FR-035**: System SHALL provide doctests for all public APIs
+**FR-036**: System SHALL maintain comprehensive README with examples
+**FR-037**: System SHALL publish documentation on docs.rs
+**FR-038**: System SHALL maintain CHANGELOG with migration notes
+
+## 4. Non-Functional Requirements
+
+### 4.1 Performance
+
+**NFR-001**: Error creation SHALL NOT allocate on the happy path
+**NFR-002**: Metadata attachment SHALL use `Vec::with_capacity` for known sizes
+**NFR-003**: Error conversions SHALL complete in <100ns for common paths (measured via criterion)
+**NFR-004**: RFC 7807 serialization SHALL complete in <500ns for typical errors
+**NFR-005**: Performance regressions >10% SHALL fail CI benchmarks
+
+### 4.2 Memory Safety
+
+**NFR-006**: System SHALL contain zero unsafe code
+**NFR-007**: System SHALL pass Miri tests under stacked borrows
+**NFR-008**: System SHALL prevent memory leaks (validated via leak sanitizer)
+**NFR-009**: System SHALL use only safe abstractions from std and alloc
+
+### 4.3 Code Quality
+
+**NFR-010**: System SHALL maintain >95% code coverage (target: 100%)
+**NFR-011**: System SHALL pass clippy with `-D warnings`
+**NFR-012**: System SHALL format code with `cargo +nightly fmt`
+**NFR-013**: System SHALL pass cargo-deny license and advisory checks
+**NFR-014**: System SHALL pass cargo-audit security vulnerability checks
+
+### 4.4 Compatibility
+
+**NFR-015**: System SHALL support MSRV 1.90
+**NFR-016**: System SHALL support Rust edition 2024
+**NFR-017**: System SHALL support no_std environments (with alloc)
+**NFR-018**: System SHALL support WASM targets (with frontend feature)
+**NFR-019**: System SHALL maintain semver compatibility guarantees
+
+### 4.5 Build Characteristics
+
+**NFR-020**: Core crate SHALL compile in <30s on release profile
+**NFR-021**: Full feature set SHALL compile in <60s on release profile
+**NFR-022**: Default feature set SHALL have <10 direct dependencies
+**NFR-023**: Release builds SHALL enable LTO and single codegen unit
+**NFR-024**: Documentation builds SHALL complete without warnings
+
+### 4.6 Testing
+
+**NFR-025**: System SHALL include unit tests for all functions
+**NFR-026**: System SHALL include integration tests for all transport adapters
+**NFR-027**: System SHALL include doctests for all public APIs
+**NFR-028**: System SHALL test error paths, not just happy paths
+**NFR-029**: System SHALL test concurrent error handling (no data races)
+**NFR-030**: System SHALL test resource cleanup (no file/socket leaks)
+
+### 4.7 CI/CD
+
+**NFR-031**: CI SHALL run on every PR and main branch push
+**NFR-032**: CI SHALL test MSRV and stable Rust in matrix
+**NFR-033**: CI SHALL run fmt, clippy, tests, coverage, benchmarks, audit
+**NFR-034**: CI SHALL fail on any warnings or test failures
+**NFR-035**: CI SHALL upload coverage reports to Codecov
+**NFR-036**: CI SHALL cancel redundant runs via concurrency groups
+
+### 4.8 Documentation
+
+**NFR-037**: Every public type SHALL have doc comments with examples
+**NFR-038**: Every public function SHALL document parameters and return values
+**NFR-039**: Complex algorithms SHALL have explanatory comments
+**NFR-040**: Migration guides SHALL document breaking changes
+**NFR-041**: Architecture decisions SHALL be documented in ADRs
+
+## 5. Architecture Decision Records
+
+### 5.1 ADR-001: Framework-Agnostic Core
+
+**Status**: Accepted
+**Context**: Need to support multiple web frameworks and non-HTTP use cases
+**Decision**: Core types in separate crate with optional transport adapters via features
+**Consequences**:
+- Positive: Reusable across projects, no framework lock-in
+- Positive: Smaller compile times for users not needing all transports
+- Negative: Requires feature flag management
+- Negative: Transport impls must be maintained separately
+
+### 5.2 ADR-002: Typed Metadata Over String Maps
+
+**Status**: Accepted
+**Context**: Need structured telemetry without losing type safety
+**Decision**: Provide typed field builders (i64, u64, Duration, IpAddr) with per-field redaction
+**Consequences**:
+- Positive: Type-safe context attachment
+- Positive: Granular redaction control
+- Positive: Better telemetry backend integration
+- Negative: More complex API than simple HashMap<String, String>
+- Negative: Serialization logic must handle multiple types
+
+### 5.3 ADR-003: Native Derive Macros
+
+**Status**: Accepted
+**Context**: Need to integrate domain errors without manual glue code
+**Decision**: Implement derive macros compatible with thiserror syntax plus masterror extensions
+**Consequences**:
+- Positive: Seamless migration from thiserror
+- Positive: Reduced boilerplate
+- Positive: Compile-time validation of mappings
+- Negative: Proc macro complexity
+- Negative: Error messages from macros can be cryptic
+
+### 5.4 ADR-004: Conservative HTTP/gRPC Mappings
+
+**Status**: Accepted
+**Context**: Need consistent error classification across transports
+**Decision**: Provide default mappings with override capability
+**Consequences**:
+- Positive: Consistent out-of-box behavior
+- Positive: Reduces mapping errors
+- Positive: Teams can customize per domain
+- Negative: Defaults may not fit all use cases
+- Negative: Requires documentation of mapping rationale
+
+### 5.5 ADR-005: No Unsafe Code
+
+**Status**: Accepted
+**Context**: Target WASM and security-critical services
+**Decision**: Implement all functionality with safe Rust abstractions
+**Consequences**:
+- Positive: Memory safety guarantees
+- Positive: WASM compatibility
+- Positive: Easier to audit
+- Negative: May lose some performance optimizations
+- Negative: Cannot use certain low-level tricks
+
+### 5.6 ADR-006: Opt-In Feature Flags
+
+**Status**: Accepted
+**Context**: Avoid forcing dependencies on users who don't need them
+**Decision**: All integrations and transports behind opt-in features, no defaults
+**Consequences**:
+- Positive: Minimal dependency footprint
+- Positive: Faster compile times for minimal use cases
+- Positive: Users only pay for what they use
+- Negative: Users must explicitly enable features
+- Negative: Documentation must explain feature combinations
+
+### 5.7 ADR-007: Turnkey Module for Rapid Adoption
+
+**Status**: Accepted
+**Context**: Teams want opinionated defaults for quick onboarding
+**Decision**: Provide optional turnkey module with pre-built catalog and helpers
+**Consequences**:
+- Positive: Faster time to value
+- Positive: Consistent baseline across teams
+- Positive: Can still customize after adoption
+- Negative: Adds maintenance burden
+- Negative: May not fit all domain models
+
+### 5.8 ADR-008: MSRV Policy
+
+**Status**: Accepted
+**Context**: Balance modern Rust features with ecosystem compatibility
+**Decision**: MSRV 1.90 with edition 2024 support
+**Consequences**:
+- Positive: Access to latest stable features
+- Positive: Future-proof for edition migration
+- Negative: Excludes older Rust installations
+- Mitigation: MSRV bumps are semver-minor per Cargo policy
+
+## 6. Design Tradeoffs
+
+### 6.1 Type Safety vs Ergonomics
+
+**Choice**: Typed metadata fields over `HashMap<String, String>`
+**Rationale**: Compile-time type checking prevents runtime errors; redaction policies require field types
+**Alternative**: Generic string maps (used by many logging libraries)
+**Impact**: Slightly more verbose API, but safer and more observable
+
+### 6.2 Feature Flags vs Monolithic Crate
+
+**Choice**: Extensive feature flags with no defaults
+**Rationale**: Minimize compile time and dependency footprint for minimal use cases
+**Alternative**: All-in-one crate with all features enabled
+**Impact**: Users must read docs to enable features, but gain significant compile time improvements
+
+### 6.3 thiserror Compatibility vs Novel Syntax
+
+**Choice**: Derive macros compatible with thiserror syntax
+**Rationale**: Lower migration barrier, familiar to Rust developers
+**Alternative**: Completely novel derive syntax
+**Impact**: Constrained by thiserror design choices, but easier adoption
+
+### 6.4 Conservative Defaults vs Domain Flexibility
+
+**Choice**: Opinionated HTTP/gRPC mappings with override capability
+**Rationale**: Consistency out of box, but allow customization
+**Alternative**: No default mappings, require explicit configuration
+**Impact**: Works immediately for 80% of use cases, customizable for edge cases
+
+### 6.5 Zero Unsafe vs Performance
+
+**Choice**: No unsafe code, even if it costs some performance
+**Rationale**: Memory safety and WASM compatibility trump marginal perf gains
+**Alternative**: Targeted unsafe for hot paths
+**Impact**: May be slightly slower than hand-optimized alternatives, but safer
+
+## 7. Future Considerations
+
+### 7.1 Potential Enhancements
+
+1. **Async context propagation**: Integrate with tokio tracing spans
+2. **Error recovery strategies**: Optional retry/fallback builders
+3. **Metric integration**: Automatic error counters per kind/code
+4. **OpenTelemetry**: Native span/event export
+5. **Custom transports**: GraphQL, Protobuf, MessagePack adapters
+
+### 7.2 Known Limitations
+
+1. **Static messages**: Error messages are not localized at runtime
+2. **No error recovery**: Library does not provide retry/circuit breaker logic
+3. **Sync-first design**: Async-specific patterns (like tokio task cancellation) require manual integration
+4. **JSON-only Problem Details**: XML RFC 7807 not currently supported
+
+### 7.3 Maintenance Commitments
+
+1. **MSRV updates**: Review quarterly, bump only for compelling features
+2. **Dependency updates**: Monitor via Dependabot, apply security patches within 48 hours
+3. **Breaking changes**: Follow semver strictly, provide migration guides
+4. **Feature requests**: Prioritize framework-agnostic features over framework-specific
+
+## 8. Acceptance Criteria
+
+A release is considered ready when:
+
+1. All functional requirements (FR-001 through FR-038) are implemented
+2. All non-functional requirements (NFR-001 through NFR-041) are verified
+3. Code coverage is >95% (target: 100%)
+4. CI passes on MSRV and stable Rust
+5. Documentation builds without warnings
+6. Benchmarks show no regressions >10%
+7. Manual testing validates all transport adapters
+8. CHANGELOG documents all user-facing changes
+9. Migration guide exists for breaking changes
+10. Security audit passes (cargo-audit, cargo-deny)
diff --git a/SECURITY.md b/SECURITY.md
index bc99130..1b57b7a 100644
--- a/SECURITY.md
+++ b/SECURITY.md
@@ -8,20 +8,177 @@ SPDX-License-Identifier: MIT
 
 ## Supported Versions
 
-Use this section to tell people about which versions of your project are
-currently being supported with security updates.
+We actively support the following versions with security updates:
 
-| Version | Supported          |
-| ------- | ------------------ |
-| 5.1.x   | :white_check_mark: |
-| 5.0.x   | :x:                |
-| 4.0.x   | :white_check_mark: |
-| < 4.0   | :x:                |
+| Version | Supported          | MSRV  | Status      |
+| ------- | ------------------ | ----- | ----------- |
+| 0.24.x  | :white_check_mark: | 1.90  | Active      |
+| 0.23.x  | :x:                | 1.90  | Deprecated  |
+| < 0.23  | :x:                | 1.70+ | Deprecated  |
+
+Security patches are released as patch versions (e.g., 0.24.19 → 0.24.20) for the actively supported version line.
 
 ## Reporting a Vulnerability
 
-Use this section to tell people how to report a vulnerability.
+We take security vulnerabilities seriously. If you discover a security issue in masterror, please report it responsibly.
+
+### Reporting Process
+
+1. **Do NOT** open a public GitHub issue for security vulnerabilities
+2. **Email** security reports to: **andrey.rozanov.vl@gmail.com**
+3. **Include** the following information:
+   - Description of the vulnerability
+   - Steps to reproduce or proof-of-concept
+   - Affected versions (if known)
+   - Potential impact assessment
+   - Suggested fix (if available)
+
+### Response Timeline
+
+- **Acknowledgment**: Within 48 hours of report
+- **Initial assessment**: Within 5 business days
+- **Fix development**: Varies by severity (critical: <7 days, high: <14 days)
+- **Coordinated disclosure**: After patch is released and users have time to update
+
+### Security Update Process
+
+1. Vulnerability confirmed and assessed
+2. Fix developed in private repository
+3. Patch released as new version
+4. Security advisory published on GitHub
+5. Disclosure made after users have time to update (typically 7-14 days)
+
+## Security Best Practices
+
+When using masterror in production:
+
+### 1. Dependency Management
+
+- **Use latest stable version**: Security fixes are not backported to old versions
+- **Enable Dependabot**: Automatically detect vulnerable dependencies
+- **Run cargo-audit**: Regularly check for known vulnerabilities
+
+```bash
+cargo install cargo-audit
+cargo audit
+```
+
+### 2. Error Message Redaction
+
+- **Never expose sensitive data** in error messages without redaction
+- **Use redaction policies** for PII (Personally Identifiable Information)
+
+```rust
+use masterror::{AppError, field, RedactionPolicy};
+
+let err = AppError::internal("auth failed")
+    .with_field(field::str_redacted(
+        "user_email",
+        email,
+        RedactionPolicy::Hash
+    ));
+```
+
+### 3. Production Configuration
+
+- **Disable backtraces** in production (avoids leaking internal paths)
+- **Limit metadata fields** (avoid exposing internal state)
+- **Use message redaction** for user-facing errors
+
+```toml
+[dependencies]
+masterror = { version = "0.24", features = ["std", "axum"], default-features = false }
+```
+
+### 4. Source Error Handling
+
+- **Avoid exposing third-party error details** to end users
+- **Log detailed errors** internally, return sanitized errors to clients
+
+```rust
+match db.query().await {
+    Ok(result) => Ok(result),
+    Err(e) => {
+        // Log full error internally
+        tracing::error!("Database error: {:?}", e);
+
+        // Return sanitized error to client
+        Err(AppError::service("database unavailable"))
+    }
+}
+```
+
+### 5. Supply Chain Security
+
+- **Verify crate signatures**: Use cargo-vet for supply chain verification
+- **Review dependencies**: Audit transitive dependencies periodically
+- **Pin versions**: Use exact versions in Cargo.lock for reproducible builds
+
+## Known Security Considerations
+
+### 1. Error Source Chains
+
+Error source chains may contain sensitive information from third-party libraries. Always review what is exposed to end users.
+
+### 2. Metadata Serialization
+
+Metadata fields are serialized in responses. Ensure redaction policies are correctly applied before exposing errors via HTTP/gRPC.
+
+### 3. Backtrace Leakage
+
+Backtraces can reveal internal file paths and stack frames. Disable the `backtrace` feature in production or implement custom filtering.
+
+### 4. Timing Attacks
+
+Error handling paths should not reveal timing information that could be exploited (e.g., database existence checks via different error latencies). This is application-specific and not handled by masterror.
+
+## Security Audits
+
+- **Internal audit**: Continuous review by maintainers
+- **cargo-audit**: Automated dependency vulnerability scanning in CI
+- **cargo-deny**: License and advisory checking in CI
+- **Community review**: Open source code reviewed by users
+
+## Security-Related Features
+
+### No Unsafe Code
+
+masterror contains **zero unsafe code**, eliminating entire classes of memory safety vulnerabilities:
+
+```toml
+[lints.rust]
+unsafe_code = "forbid"
+```
+
+### Send + Sync Guarantees
+
+All error types implement `Send + Sync`, ensuring safe concurrent usage without data races.
+
+### Type Safety
+
+- Strongly typed error kinds (no string matching)
+- Compile-time validation of transport mappings
+- No type confusion between error categories
+
+## Vulnerability Disclosure History
+
+No security vulnerabilities have been reported to date.
+
+Future disclosures will be listed here with:
+- CVE identifier (if applicable)
+- Affected versions
+- Severity rating
+- Mitigation steps
+- Fixed in version
+
+## Security Contact
+
+**Primary contact**: andrey.rozanov.vl@gmail.com
+
+**PGP key**: Available on request for encrypted communication
+
+## Additional Resources
 
-Tell them where to go, how often they can expect to get an update on a
-reported vulnerability, what to expect if the vulnerability is accepted or
-declined, etc.
+- [Rust Security Guidelines](https://anssi-fr.github.io/rust-guide/)
+- [OWASP Error Handling Cheat Sheet](https://cheatsheetseries.owasp.org/cheatsheets/Error_Handling_Cheat_Sheet.html)
+- [Cargo Security Advisories](https://rustsec.org/)