diff --git a/.memory/alignment_checking/README.md b/.memory/alignment_checking/README.md
index 716d627..eba7469 100644
--- a/.memory/alignment_checking/README.md
+++ b/.memory/alignment_checking/README.md
@@ -22,7 +22,7 @@ Python is the reference style (code-first, minimal prose). All languages should
 - `—` = missing, intentional (language doesn't need this)
 - `TODO` = missing, should add
 - `DEL` = present, should remove or merge
-- `Py#` / `TS#` / `Go#` = section order in file (should monotonically increase if order is aligned)
+- `Py#` / `TS#` / `Rb#` / `Go#` = section order in file (should monotonically increase if order is aligned)
 
 ## Implementation Status
 
@@ -30,6 +30,8 @@ Python is the reference style (code-first, minimal prose). All languages should
 
 **Go:** ✅ COMPLETE (2026-03-17) — All Go reference files created and aligned.
 
+**Ruby:** ⏳ IN PROGRESS (2026-03-16) — Ruby columns added to all alignment tracking files. Ruby reference files not yet created.
+
 ## Files
 
 Each file in this directory tracks alignment for a corresponding reference file:
diff --git a/.memory/alignment_checking/advanced-features.md b/.memory/alignment_checking/advanced-features.md
index 532976f..c54d6fd 100644
--- a/.memory/alignment_checking/advanced-features.md
+++ b/.memory/alignment_checking/advanced-features.md
@@ -2,22 +2,24 @@
 
 ## Section Inventory
 
-| Section | Core | Python | Py# | TypeScript | TS# | Go |
-|---------|------|--------|-----|------------|-----|-----|
-| Schedules | — | ✓ | 1 | ✓ | 1 | |
-| Async Activity Completion | — | ✓ | 2 | ✓ | 2 | |
-| Sandbox Customization | — | ✓ | 3 | — | — | |
-| Gevent Compatibility Warning | — | ✓ | 4 | — | — | |
-| Worker Tuning | — | ✓ | 5 | ✓ | 3 | |
-| Workflow Init Decorator | — | ✓ | 6 | — | — | |
-| Workflow Failure Exception Types | — | ✓ | 7 | — | — | |
-| Continue-as-New | — | — | — | — | — | |
-| Workflow Updates | — | — | — | — | — | |
-| Nexus Operations | — | — | — | — | — | |
-| Activity Cancellation and Heartbeating | — | — | — | — | — | |
-| Sinks | — | — | — | ✓ | 4 | |
-| CancellationScope Patterns | — | — | — | — | — | |
-| Best Practices | — | — | — | — | — | |
+| Section | Core | Python | Py# | TypeScript | TS# | Ruby | Rb# | Go |
+|---------|------|--------|-----|------------|-----|------|-----|-----|
+| Schedules | — | ✓ | 1 | ✓ | 1 | TODO | 1 | |
+| Async Activity Completion | — | ✓ | 2 | ✓ | 2 | TODO | 2 | |
+| Sandbox Customization | — | ✓ | 3 | — | — | — | — | |
+| Gevent Compatibility Warning | — | ✓ | 4 | — | — | — | — | |
+| Worker Tuning | — | ✓ | 5 | ✓ | 3 | TODO | 3 | |
+| Workflow Init Decorator | — | ✓ | 6 | — | — | — | — | |
+| Workflow Failure Exception Types | — | ✓ | 7 | — | — | TODO | 4 | |
+| Continue-as-New | — | — | — | — | — | — | — | |
+| Workflow Updates | — | — | — | — | — | — | — | |
+| Nexus Operations | — | — | — | — | — | — | — | |
+| Activity Cancellation and Heartbeating | — | — | — | — | — | — | — | |
+| Sinks | — | — | — | ✓ | 4 | — | — | |
+| Activity Concurrency and Executors | — | — | — | — | — | TODO | 5 | |
+| Rails Integration | — | — | — | — | — | TODO | 6 | |
+| CancellationScope Patterns | — | — | — | — | — | — | — | |
+| Best Practices | — | — | — | — | — | — | — | |
 
 ## Style Compliance
 
@@ -25,25 +27,43 @@
 |----------|--------|-------|
 | Python | ✓ reference | 7 sections |
 | TypeScript | ✓ aligned | 4 sections (removed duplicates) |
+| Ruby | — | Not started |
 | Go | ✓ aligned | 4 sections — Schedules, Async Completion, Worker Tuning, Sessions |
 
 ## Status
 
-**Go-specific notes:**
-- Schedules: `client.ScheduleClient` — same concept as Python/TS
-- Async Activity Completion: `activity.GetInfo(ctx).TaskToken` + `client.CompleteActivity` / `client.CompleteActivityByID`
-- Worker Tuning: `worker.Options` — `MaxConcurrentActivityExecutionSize`, `MaxConcurrentWorkflowTaskExecutionSize`, `MaxConcurrentActivityTaskPollers`
-- Sessions: Go-specific feature — `workflow.CreateSession(ctx, options)` pins activities to a specific worker. Useful for file processing where activities need local state.
 **Intentionally missing (`—`):**
 - Core column: advanced features are implementation-specific
-- Sandbox Customization: Python-specific; Go has no sandbox
+- Sandbox Customization: Python-specific; Ruby/Go have no sandbox
 - Gevent Compatibility Warning: Python-specific
-- Workflow Init Decorator: Python-specific
-- Workflow Failure Exception Types: Python-specific
+- Workflow Init Decorator: Python-specific (`@workflow.init`); Ruby uses `initialize` naturally; Go N/A
 - Sinks: TS-specific feature
-- Sessions: Go-specific (not in Python/TS)
+- Workflow Failure Exception Types: Python has `workflow_failure_exception_types`; Ruby has similar `workflow_failure_exception_type` class method — should include; Go: Python-specific
+- Sessions: Go-specific (not in Python/TS/Ruby)
 - Interceptors: Decided not to include for any language (all SDKs have them, but too advanced for current scope)
 
+**Ruby notes:**
+- Schedules: `Temporalio::Client::ScheduleHandle` — same API pattern as other SDKs
+- Async Activity Completion: `Temporalio::Client::AsyncActivityHandle` for completing activities from external processes
+- Worker Tuning: `max_concurrent_workflow_tasks`, `max_concurrent_activities`, resource-based auto-tuning
+- Workflow Failure Exception Types: `workflow_failure_exception_type` on workflow class or `workflow_failure_exception_types` on worker
+- Activity Concurrency and Executors: Ruby-specific — `Temporalio::Worker::ActivityExecutor::ThreadPool`, fiber-based execution, `max_concurrent_activities`
+- Rails Integration: Ruby-specific — ActiveRecord concerns, lazy/eager loading, Zeitwerk compatibility
+
+**Go notes:**
+- Schedules: `client.ScheduleClient` — same concept as Python/TS
+- Async Activity Completion: `activity.GetInfo(ctx).TaskToken` + `client.CompleteActivity` / `client.CompleteActivityByID`
+- Worker Tuning: `worker.Options` — `MaxConcurrentActivityExecutionSize`, `MaxConcurrentWorkflowTaskExecutionSize`, `MaxConcurrentActivityTaskPollers`
+- Sessions: Go-specific feature — `workflow.CreateSession(ctx, options)` pins activities to a specific worker. Useful for file processing where activities need local state.
+
+**Sections needing review (empty cells):**
+- Ruby column: all TODO — Ruby reference files not yet created
+
 **Order alignment:** N/A — Files have different structures by design
 
-**Style alignment:** ✅ Complete (Python, TypeScript)
+**Style alignment:** ✅ Complete (Python, TypeScript, Go)
+- Python: 7 sections (Schedules, Async Activity Completion, Sandbox Customization, Gevent Warning, Worker Tuning, Workflow Init, Failure Exception Types)
+- TypeScript: 4 sections (Schedules, Async Activity Completion, Worker Tuning, Sinks)
+- Go: 4 sections (Schedules, Async Completion, Worker Tuning, Sessions)
+- Ruby: ~6 sections planned (Schedules, Async Activity Completion, Worker Tuning, Failure Exception Types, Activity Concurrency/Executors, Rails Integration)
+- Removed duplicates from TS (Continue-as-New, Workflow Updates, CancellationScope Patterns, Nexus Operations, Activity Cancellation, Best Practices — all covered elsewhere)
diff --git a/.memory/alignment_checking/data-handling.md b/.memory/alignment_checking/data-handling.md
index 441e825..f9f566d 100644
--- a/.memory/alignment_checking/data-handling.md
+++ b/.memory/alignment_checking/data-handling.md
@@ -2,20 +2,22 @@
 
 ## Section Inventory
 
-| Section | Core | Python | Py# | TypeScript | TS# | Go | Go# |
-|---------|------|--------|-----|------------|-----|-----|-----|
-| Overview | — | ✓ | 1 | ✓ | 1 | ✓ | 1 |
-| Default Data Converter | — | ✓ | 2 | ✓ | 2 | ✓ | 2 |
-| Pydantic Integration | — | ✓ | 3 | — | — | — | — |
-| Custom Data Converter | — | ✓ | 4 | ✓ | 3 | ✓ | 3 |
-| Composition of Payload Converters | — | — | — | ✓ | 4 | ✓ | 4 |
-| Protobuf Support | — | — | — | ✓ | 5 | ✓ | 5 |
-| Payload Encryption | — | ✓ | 5 | ✓ | 6 | ✓ | 6 |
-| Search Attributes | — | ✓ | 6 | ✓ | 7 | ✓ | 7 |
-| Workflow Memo | — | ✓ | 7 | ✓ | 8 | ✓ | 8 |
-| Large Payloads | — | — | — | — | — | — | — |
-| Deterministic APIs for Values | — | ✓ | 8 | — | — | — | — |
-| Best Practices | — | ✓ | 9 | ✓ | 9 | ✓ | 9 |
+| Section | Core | Python | Py# | TypeScript | TS# | Ruby | Rb# | Go | Go# |
+|---------|------|--------|-----|------------|-----|------|-----|-----|-----|
+| Overview | — | ✓ | 1 | ✓ | 1 | TODO | 1 | ✓ | 1 |
+| Default Data Converter | — | ✓ | 2 | ✓ | 2 | TODO | 2 | ✓ | 2 |
+| Pydantic Integration | — | ✓ | 3 | — | — | — | — | — | — |
+| ActiveModel Integration | — | — | — | — | — | TODO | 3 | — | — |
+| Custom Data Converter | — | ✓ | 4 | ✓ | 3 | TODO | 4 | ✓ | 3 |
+| Composition of Payload Converters | — | — | — | ✓ | 4 | — | — | ✓ | 4 |
+| Converter Hints | — | — | — | — | — | TODO | 5 | — | — |
+| Protobuf Support | — | — | — | ✓ | 5 | — | — | ✓ | 5 |
+| Payload Encryption | — | ✓ | 5 | ✓ | 6 | TODO | 6 | ✓ | 6 |
+| Search Attributes | — | ✓ | 6 | ✓ | 7 | TODO | 7 | ✓ | 7 |
+| Workflow Memo | — | ✓ | 7 | ✓ | 8 | TODO | 8 | ✓ | 8 |
+| Large Payloads | — | — | — | — | — | — | — | — | — |
+| Deterministic APIs for Values | — | ✓ | 8 | — | — | TODO | 9 | — | — |
+| Best Practices | — | ✓ | 9 | ✓ | 9 | TODO | 10 | ✓ | 9 |
 
 ## Style Compliance
 
@@ -23,10 +25,20 @@
 |----------|--------|-------|
 | Python | ✓ reference | — |
 | TypeScript | ✓ aligned | — |
+| Ruby | — | Not started |
 | Go | ✓ aligned | JSON default, protobuf native, converter.CompositeDataConverter |
 
 ## Status
 
+**Ruby notes:**
+- Default converter: nil, bytes, Protobuf, then JSON (using Ruby's `JSON` module with `create_additions: true`)
+- Symbol keys become string keys on deserialization
+- JSON Additions supported but not cross-language compatible
+- ActiveModel: needs `ActiveModelJSONSupport` mixin for proper serialization
+- Converter Hints: unique to Ruby — `workflow_arg_hint MyClass`, `workflow_result_hint MyClass` — needed because Ruby lacks type hints
+- Search Attributes: `Temporalio::SearchAttributes::Key.new('name', type)`, `Temporalio::Workflow.upsert_search_attributes`
+- Deterministic APIs: `Temporalio::Workflow.random` (SecureRandom replacement), `Temporalio::Workflow.now` (Time.now replacement), `Temporalio::Workflow.uuid` (UUID generation)
+
 **Go-specific notes:**
 - Default Data Converter: Go uses `converter.NewCompositeDataConverter()` with JSON as default — chain: NilPayloadConverter, ByteSlicePayloadConverter, ProtoPayloadConverter, ProtoJSONPayloadConverter, JSONPayloadConverter
 - Custom Data Converter: implement `converter.DataConverter` interface
@@ -39,10 +51,14 @@
 
 **Intentionally missing (`—`):**
 - Core column: data handling is implementation-specific
-- Pydantic Integration: Python-specific
-- Deterministic APIs for Values: Python-specific; Go covers in determinism.md Safe Builtin Alternatives
+- Pydantic Integration: Python-specific (TS uses plain JSON/types)
+- ActiveModel Integration: Ruby-specific (equivalent of Pydantic)
+- Composition of Payload Converters: TS/Go-specific section
+- Converter Hints: Ruby-specific (`workflow_arg_hint`, `workflow_result_hint` — needed because Ruby lacks type annotations)
+- Protobuf Support: TS/Go-specific section (Ruby/Python handle protobufs via default converter)
+- Deterministic APIs for Values: Python has `workflow.uuid4()`, `workflow.random()`; Ruby has `Temporalio::Workflow.random/now/uuid`; Go covers in determinism.md
 - Large Payloads: Moved to core/patterns.md and core/gotchas.md
 
-**Order alignment:** ✅ ALIGNED — Go sections follow same order as Python/TypeScript
+**Order alignment:** ✅ ALIGNED — Ruby follows Python order with Ruby-specific additions (ActiveModel, Converter Hints)
 
-**Style alignment:** ✅ Complete (Python, TypeScript)
+**Style alignment:** ✅ Complete (Python, TypeScript, Go). Ruby: ~10 sections planned.
diff --git a/.memory/alignment_checking/determinism-protection.md b/.memory/alignment_checking/determinism-protection.md
index c0ef0f0..ef2805d 100644
--- a/.memory/alignment_checking/determinism-protection.md
+++ b/.memory/alignment_checking/determinism-protection.md
@@ -2,24 +2,28 @@
 
 ## Section Inventory
 
-| Section | Core | Python | Py# | TypeScript | TS# | Go | Go# |
-|---------|------|--------|-----|------------|-----|-----|-----|
-| Overview | — | ✓ | 1 | ✓ | 1 | ✓ | 1 |
-| How the Sandbox Works | — | ✓ | 2 | — | — | — | — |
-| Import Blocking | — | — | — | ✓ | 2 | — | — |
-| Forbidden Operations | — | ✓ | 3 | — | — | — | — |
-| Function Replacement | — | — | — | ✓ | 3 | — | — |
-| workflowcheck Static Analysis | — | — | — | — | — | ✓ | 2 |
-| Determinism Rules | — | — | — | — | — | ✓ | 3 |
-| Pass-Through Pattern | — | ✓ | 4 | — | — | — | — |
-| Importing Activities | — | ✓ | 5 | — | — | — | — |
-| Disabling the Sandbox | — | ✓ | 6 | — | — | — | — |
-| Customizing Invalid Module Members | — | ✓ | 7 | — | — | — | — |
-| Import Notification Policy | — | ✓ | 8 | — | — | — | — |
-| Disable Lazy sys.modules Passthrough | — | ✓ | 9 | — | — | — | — |
-| File Organization | — | ✓ | 10 | — | — | — | — |
-| Common Issues | — | ✓ | 11 | — | — | — | — |
-| Best Practices | — | ✓ | 12 | — | — | ✓ | 4 |
+| Section | Core | Python | Py# | TypeScript | TS# | Ruby | Rb# | Go | Go# |
+|---------|------|--------|-----|------------|-----|------|-----|-----|-----|
+| Overview | — | ✓ | 1 | ✓ | 1 | TODO | 1 | ✓ | 1 |
+| How the Sandbox Works | — | ✓ | 2 | — | — | — | — | — | — |
+| How Illegal Call Tracing Works | — | — | — | — | — | TODO | 2 | — | — |
+| Import Blocking | — | — | — | ✓ | 2 | — | — | — | — |
+| Forbidden Operations | — | ✓ | 3 | — | — | TODO | 3 | — | — |
+| Function Replacement | — | — | — | ✓ | 3 | — | — | — | — |
+| Durable Fiber Scheduler | — | — | — | — | — | TODO | 4 | — | — |
+| workflowcheck Static Analysis | — | — | — | — | — | — | — | ✓ | 2 |
+| Determinism Rules | — | — | — | — | — | — | — | ✓ | 3 |
+| Pass-Through Pattern | — | ✓ | 4 | — | — | — | — | — | — |
+| Importing Activities | — | ✓ | 5 | — | — | — | — | — | — |
+| Disabling the Sandbox | — | ✓ | 6 | — | — | — | — | — | — |
+| Disabling Illegal Call Tracing | — | — | — | — | — | TODO | 5 | — | — |
+| Customizing Invalid Module Members | — | ✓ | 7 | — | — | — | — | — | — |
+| Customizing Illegal Calls | — | — | — | — | — | TODO | 6 | — | — |
+| Import Notification Policy | — | ✓ | 8 | — | — | — | — | — | — |
+| Disable Lazy sys.modules Passthrough | — | ✓ | 9 | — | — | — | — | — | — |
+| File Organization | — | ✓ | 10 | — | — | — | — | — | — |
+| Common Issues | — | ✓ | 11 | — | — | TODO | 7 | — | — |
+| Best Practices | — | ✓ | 12 | — | — | TODO | 8 | ✓ | 4 |
 
 ## Style Compliance
 
@@ -27,10 +31,21 @@
 |----------|--------|-------|
 | Python | ✓ reference | Comprehensive (12 sections) |
 | TypeScript | ✓ aligned | Minimal (3 sections) — V8 is automatic |
+| Ruby | — | Not started |
 | Go | ✓ aligned | Minimal (4 sections) — no runtime sandbox, convention + static analysis |
 
 ## Status
 
+**Ruby notes:**
+- Ruby's approach is fundamentally different from Python (sandbox) and TS (V8): uses TracePoint for illegal call tracing + custom Fiber::Scheduler for durable fibers
+- "How Illegal Call Tracing Works": TracePoint catches illegal calls on workflow thread, configurable via `illegal_workflow_calls` worker param
+- "Durable Fiber Scheduler": Custom Fiber::Scheduler makes fibers deterministic; `Kernel.sleep`, `Mutex` etc. are disabled by default
+- "Disabling Illegal Call Tracing": `Temporalio::Workflow::Unsafe.illegal_call_tracing_disabled` block
+- "Customizing Illegal Calls": `illegal_workflow_calls` parameter on worker, `Temporalio::Worker.default_illegal_workflow_calls`
+- `durable_scheduler_disabled` (implies `illegal_call_tracing_disabled`), `io_enabled` for IO wait
+- Python's Import/Module sections don't apply (Ruby doesn't have module-level sandbox)
+- Ruby estimated ~8 sections (moderate — more than TS's 3, less than Python's 12)
+
 **Go-specific notes:**
 - Go has NO runtime sandbox (unlike Python's import-restricting sandbox or TS's V8 isolate)
 - Determinism enforcement is purely by developer convention + optional static analysis
@@ -51,4 +66,5 @@
 **Style alignment:** ⚠️ Very different structures (intentional, different protection mechanisms)
 - Python: Comprehensive (12 sections) — complex sandbox with many customization options
 - TypeScript: Minimal (3 sections) — V8 sandbox is mostly automatic
+- Ruby: Moderate (~8 sections) — TracePoint + Fiber Scheduler with customization options
 - Go: Minimal (4 sections) — no sandbox, convention-based with static analysis tool
diff --git a/.memory/alignment_checking/determinism.md b/.memory/alignment_checking/determinism.md
index e70299a..2c1b413 100644
--- a/.memory/alignment_checking/determinism.md
+++ b/.memory/alignment_checking/determinism.md
@@ -2,19 +2,19 @@
 
 ## Section Inventory
 
-| Section | Core | Core# | Python | Py# | TypeScript | TS# | Go | Go# |
-|---------|------|-------|--------|-----|------------|-----|-----|-----|
-| Overview | ✓ | 1 | ✓ | 1 | ✓ | 1 | ✓ | 1 |
-| Why Determinism Matters | ✓ | 2 | ✓ | 2 | ✓ | 2 | ✓ | 2 |
-| Sources of Non-Determinism | ✓ | 3 | — | — | — | — | — | — |
-| Central Concept: Activities | ✓ | 4 | — | — | — | — | — | — |
-| SDK Protection / Sandbox | ✓ | 5 | ✓ | 6 | ✓ | 3 | — | — |
-| Forbidden Operations | — | — | ✓ | 3 | ✓ | 4 | ✓ | 3 |
-| Safe Builtin Alternatives | — | — | ✓ | 4 | — | — | ✓ | 4 |
-| Detecting Non-Determinism | ✓ | 6 | — | — | — | — | — | — |
-| Recovery from Non-Determinism | ✓ | 7 | — | — | — | — | — | — |
-| Testing Replay Compatibility | — | — | ✓ | 5 | ✓ | 5 | ✓ | 5 |
-| Best Practices | ✓ | 8 | ✓ | 7 | ✓ | 6 | ✓ | 6 |
+| Section | Core | Core# | Python | Py# | TypeScript | TS# | Ruby | Rb# | Go | Go# |
+|---------|------|-------|--------|-----|------------|-----|------|-----|-----|-----|
+| Overview | ✓ | 1 | ✓ | 1 | ✓ | 1 | TODO | 1 | ✓ | 1 |
+| Why Determinism Matters | ✓ | 2 | ✓ | 2 | ✓ | 2 | TODO | 2 | ✓ | 2 |
+| Sources of Non-Determinism | ✓ | 3 | — | — | — | — | — | — | — | — |
+| Central Concept: Activities | ✓ | 4 | — | — | — | — | — | — | — | — |
+| SDK Protection / Sandbox | ✓ | 5 | ✓ | 6 | ✓ | 3 | TODO | 3 | — | — |
+| Forbidden Operations | — | — | ✓ | 3 | ✓ | 4 | TODO | 4 | ✓ | 3 |
+| Safe Builtin Alternatives | — | — | ✓ | 4 | — | — | TODO | 5 | ✓ | 4 |
+| Detecting Non-Determinism | ✓ | 6 | — | — | — | — | — | — | — | — |
+| Recovery from Non-Determinism | ✓ | 7 | — | — | — | — | — | — | — | — |
+| Testing Replay Compatibility | — | — | ✓ | 5 | ✓ | 5 | TODO | 6 | ✓ | 5 |
+| Best Practices | ✓ | 8 | ✓ | 7 | ✓ | 6 | TODO | 7 | ✓ | 6 |
 
 ## Style Compliance
 
@@ -23,10 +23,18 @@
 | Core | ✓ reference | Deep conceptual content |
 | Python | ✓ aligned | Practical focus |
 | TypeScript | ✓ aligned | Practical focus, V8 sandbox |
+| Ruby | — | Not started |
 | Go | ✓ aligned | Practical focus, no sandbox, workflowcheck tool, workflow.* replacements |
 
 ## Status
 
+**Ruby notes:**
+- Ruby's determinism protection uses Illegal Call Tracing (TracePoint) + Durable Fiber Scheduler — distinct from Python sandbox and TS V8 sandbox
+- Ruby's TracePoint catches illegal calls like `sleep`, `Time.now`, `Thread.new` at runtime
+- Ruby has safe alternatives: `Temporalio::Workflow.sleep`, `Temporalio::Workflow.now`, `Temporalio::Workflow.random`, `Temporalio::Workflow.logger`
+- Safe Builtin Alternatives section is appropriate for Ruby (similar to Python's table, but with Ruby-specific mappings)
+- Forbidden Operations section should list Ruby-specific illegal calls (e.g., `Kernel.sleep`, `Time.now` without args, `Thread.new`, `IO` operations)
+
 **Go-specific notes:**
 - SDK Protection: Go merged this into Overview (cross-references `determinism-protection.md` instead of having separate section). Marked `—` in table.
 - Testing Replay: Go cross-references `testing.md` rather than inlining code (matching Python style)
@@ -39,16 +47,17 @@
 - Sources of Non-Determinism: Core-only (conceptual categories)
 - Central Concept: Activities: Core-only (conceptual)
 - Forbidden Operations: Language-specific (Core covers in Sources)
-- Safe Builtin Alternatives: Python has table, Go will have table, TS doesn't need (V8 sandbox handles automatically)
+- Safe Builtin Alternatives: Python/Ruby/Go have tables; TS doesn't need (V8 sandbox handles automatically)
 - Detecting Non-Determinism: Core-only
 - Recovery from Non-Determinism: Core-only
 - Testing Replay Compatibility: Language-specific (Core covers in Detecting)
 
 **Order alignment:** N/A — different structures by design
 
-**Style alignment:** ✓ Well aligned (Python, TypeScript)
+**Style alignment:** ✓ Well aligned (Python, TypeScript, Go)
 - Core: Deep conceptual content (replay mechanism, commands/events, recovery)
 - Python: Practical focus (forbidden operations, safe alternatives table, sandbox)
 - TypeScript: Practical focus (V8 sandbox, forbidden operations)
-- Go will follow Python pattern: forbidden operations + safe alternatives table + workflowcheck
+- Ruby: Practical focus (TracePoint + Fiber Scheduler, forbidden calls, safe alternatives table) — ~7 sections
+- Go: Practical focus (forbidden operations, safe alternatives table, workflowcheck)
 - Good division: Core explains "why", languages explain "how"
diff --git a/.memory/alignment_checking/error-handling.md b/.memory/alignment_checking/error-handling.md
index 6b4a8f2..25b8172 100644
--- a/.memory/alignment_checking/error-handling.md
+++ b/.memory/alignment_checking/error-handling.md
@@ -2,19 +2,19 @@
 
 ## Section Inventory
 
-| Section | Core | Python | Py# | TypeScript | TS# | Go | Go# |
-|---------|------|--------|-----|------------|-----|-----|-----|
-| Overview | — | ✓ | 1 | ✓ | 1 | ✓ | 1 |
-| Application Errors/Failures | — | ✓ | 2 | ✓ | 2 | ✓ | 2 |
-| Non-Retryable Errors | — | ✓ | 3 | — | — | ✓ | 3 |
-| Activity Errors | — | — | — | ✓ | 3 | — | — |
-| Handling Activity Errors in Workflows | — | ✓ | 4 | ✓ | 4 | ✓ | 4 |
-| Retry Configuration | — | ✓ | 5 | ✓ | 5 | ✓ | 5 |
-| Timeout Configuration | — | ✓ | 6 | ✓ | 6 | ✓ | 6 |
-| Workflow Failure | — | ✓ | 7 | ✓ | 7 | ✓ | 7 |
-| Cancellation Handling in Activities | — | — | — | — | — | — | — |
-| Idempotency Patterns | — | — | — | — | — | — | — |
-| Best Practices | — | ✓ | 8 | ✓ | 9 | ✓ | 8 |
+| Section | Core | Python | Py# | TypeScript | TS# | Ruby | Rb# | Go | Go# |
+|---------|------|--------|-----|------------|-----|------|-----|-----|-----|
+| Overview | — | ✓ | 1 | ✓ | 1 | TODO | 1 | ✓ | 1 |
+| Application Errors/Failures | — | ✓ | 2 | ✓ | 2 | TODO | 2 | ✓ | 2 |
+| Non-Retryable Errors | — | ✓ | 3 | — | — | TODO | 3 | ✓ | 3 |
+| Activity Errors | — | — | — | ✓ | 3 | — | — | — | — |
+| Handling Activity Errors in Workflows | — | ✓ | 4 | ✓ | 4 | TODO | 4 | ✓ | 4 |
+| Retry Configuration | — | ✓ | 5 | ✓ | 5 | TODO | 5 | ✓ | 5 |
+| Timeout Configuration | — | ✓ | 6 | ✓ | 6 | TODO | 6 | ✓ | 6 |
+| Workflow Failure | — | ✓ | 7 | ✓ | 7 | TODO | 7 | ✓ | 7 |
+| Cancellation Handling in Activities | — | — | — | — | — | — | — | — | — |
+| Idempotency Patterns | — | — | — | — | — | — | — | — | — |
+| Best Practices | — | ✓ | 8 | ✓ | 9 | TODO | 8 | ✓ | 8 |
 
 ## Style Compliance
 
@@ -22,10 +22,20 @@
 |----------|--------|-------|
 | Python | ✓ reference | — |
 | TypeScript | ✓ aligned | Uses `log`, has retry defaults note |
+| Ruby | — | Not started |
 | Go | ✓ aligned | Go-style error handling (errors.As, error returns, no exceptions) |
 
 ## Status
 
+**Ruby notes:**
+- `Temporalio::Error::ApplicationError` with `non_retryable:` parameter
+- Any non-`ApplicationError` exception in a workflow causes workflow task failure (retried), NOT workflow failure
+- Activity exceptions auto-converted to `ApplicationError`
+- `Temporalio::RetryPolicy.new(max_interval:, initial_interval:, backoff_coefficient:, max_attempts:, non_retryable_error_types:)`
+- Timeouts: `start_to_close_timeout`, `schedule_to_close_timeout`, `schedule_to_start_timeout` (same as other SDKs)
+- `workflow_failure_exception_types` on Worker or `workflow_failure_exception_type` on Workflow class
+- `next_retry_delay:` parameter on `ApplicationError` to override retry interval
+
 **Go-specific notes:**
 - Go uses error returns (not exceptions) — `if err != nil` pattern
 - Application Errors: `temporal.NewApplicationError("msg", "type", details...)` and `temporal.NewNonRetryableApplicationError("msg", "type", cause, details...)`
@@ -39,6 +49,6 @@
 - Core column: error handling is implementation-specific
 - Activity Errors: TS-specific section (Go covers in Handling Activity Errors)
 
-**Order alignment:** ✓ Aligned — Go# monotonically increases
+**Order alignment:** ✓ Aligned — Ruby and Go# monotonically increase
 
-**Style alignment:** ✅ Complete (Python, TypeScript)
+**Style alignment:** ✅ Complete (Python, TypeScript, Go). Ruby: ~8 sections planned.
diff --git a/.memory/alignment_checking/gotchas.md b/.memory/alignment_checking/gotchas.md
index e83465f..72cadc8 100644
--- a/.memory/alignment_checking/gotchas.md
+++ b/.memory/alignment_checking/gotchas.md
@@ -2,26 +2,27 @@
 
 ## Section Inventory
 
-| Section | Core | Core# | Python | Py# | TypeScript | TS# | Go | Go# |
-|---------|------|-------|--------|-----|------------|-----|-----|-----|
-| Idempotency / Non-Idempotent Activities | ✓ | 1 | — | — | — | — | — | — |
-| Replay Safety / Side Effects & Non-Determinism | ✓ | 2 | — | — | — | — | — | — |
-| Multiple Workers with Different Code | ✓ | 3 | — | — | — | — | — | — |
-| Retry Policies / Failing Activities Too Quickly | ✓ | 4 | — | — | — | — | — | — |
-| Query Handlers / Query Handler Mistakes | ✓ | 5 | — | — | — | — | — | — |
-| File Organization | ✓ | 6 | ✓ | 1 | — | — | — | — |
-| Activity Imports | — | — | — | — | ✓ | 1 | — | — |
-| Bundling Issues | — | — | — | — | ✓ | 2 | — | — |
-| Async vs Sync Activities | — | — | ✓ | 2 | — | — | — | — |
-| Goroutines and Concurrency | — | — | — | — | — | — | ✓ | 1 |
-| Non-Deterministic Operations | — | — | — | — | — | — | ✓ | 2 |
-| Error Handling | ✓ | 8 | — | — | — | — | — | — |
-| Wrong Retry Classification | ✓ | 8 | ✓ | 3 | ✓ | 3 | ✓ | 3 |
-| Heartbeating | — | — | ✓ | 5 | ✓ | 5 | ✓ | 4 |
-| Cancellation | ✓ | 10 | ✓ | 4 | ✓ | 4 | ✓ | 5 |
-| Testing | ✓ | 7 | ✓ | 6 | ✓ | 6 | ✓ | 6 |
-| Timers and Sleep | — | — | ✓ | 7 | ✓ | 7 | ✓ | 7 |
-| Payload Size Limits | ✓ | 9 | — | — | — | — | — | — |
+| Section | Core | Core# | Python | Py# | TypeScript | TS# | Ruby | Rb# | Go | Go# |
+|---------|------|-------|--------|-----|------------|-----|------|-----|-----|-----|
+| Idempotency / Non-Idempotent Activities | ✓ | 1 | — | — | — | — | — | — | — | — |
+| Replay Safety / Side Effects & Non-Determinism | ✓ | 2 | — | — | — | — | — | — | — | — |
+| Multiple Workers with Different Code | ✓ | 3 | — | — | — | — | — | — | — | — |
+| Retry Policies / Failing Activities Too Quickly | ✓ | 4 | — | — | — | — | — | — | — | — |
+| Query Handlers / Query Handler Mistakes | ✓ | 5 | — | — | — | — | — | — | — | — |
+| File Organization | ✓ | 6 | ✓ | 1 | — | — | TODO | 1 | — | — |
+| Activity Imports | — | — | — | — | ✓ | 1 | — | — | — | — |
+| Bundling Issues | — | — | — | — | ✓ | 2 | — | — | — | — |
+| Async vs Sync Activities | — | — | ✓ | 2 | — | — | — | — | — | — |
+| Goroutines and Concurrency | — | — | — | — | — | — | — | — | ✓ | 1 |
+| Non-Deterministic Operations | — | — | — | — | — | — | — | — | ✓ | 2 |
+| Error Handling | ✓ | 8 | — | — | — | — | — | — | — | — |
+| Wrong Retry Classification | ✓ | 8 | ✓ | 3 | ✓ | 3 | TODO | 2 | ✓ | 3 |
+| Heartbeating | — | — | ✓ | 5 | ✓ | 5 | TODO | 4 | ✓ | 4 |
+| Cancellation | ✓ | 10 | ✓ | 4 | ✓ | 4 | TODO | 3 | ✓ | 5 |
+| Testing | ✓ | 7 | ✓ | 6 | ✓ | 6 | TODO | 5 | ✓ | 6 |
+| Timers and Sleep | — | — | ✓ | 7 | ✓ | 7 | TODO | 6 | ✓ | 7 |
+| Payload Size Limits | ✓ | 9 | — | — | — | — | — | — | — | — |
+| Illegal Call Tracing Gotchas | — | — | — | — | — | — | TODO | 7 | — | — |
 
 ## Style Compliance
 
@@ -30,10 +31,20 @@
 | Core | ✓ reference | Conceptual gotchas |
 | Python | ✓ aligned | Language-specific gotchas |
 | TypeScript | ✓ aligned | Language-specific gotchas |
+| Ruby | — | Not started |
 | Go | ✓ aligned | Language-specific gotchas — goroutines, channels, selectors, map range |
 
 ## Status
 
+**Ruby notes:**
+- File Organization: Ruby class-per-file convention, `require_relative` for activities in workflows
+- Wrong Retry Classification: `non_retryable: true` on `ApplicationError`, `non_retryable_error_types` in retry policy
+- Cancellation: `Temporalio::Cancellation` tokens, detached cancellation for cleanup, `Error.canceled?` helper
+- Heartbeating: `Temporalio::Activity::Context.current.heartbeat(details)`, heartbeat_details on retry
+- Testing: common testing gotchas with `WorkflowExecutor::ThreadPool`, `activity_name` for mocking
+- Timers and Sleep: `Temporalio::Workflow.sleep` vs `Kernel.sleep` (illegal), duration in seconds (Float)
+- Illegal Call Tracing Gotchas: Ruby-specific — third-party gems triggering illegal calls, using `Unsafe.illegal_call_tracing_disabled` for safe workarounds, `durable_scheduler_disabled` for IO
+
 **Go-specific notes:**
 - Goroutines and Concurrency: MUST use `workflow.Go()` not native `go`, `workflow.Channel` not native channels, `workflow.Selector` not native `select`
 - Non-Deterministic Operations: map range iteration, `time.Now()`/`time.Sleep()`, `math/rand`, accessing `os.Stdin`/`os.Stdout`/`os.Stderr`, anonymous functions as local activities (non-deterministic name — use named functions instead)
@@ -45,7 +56,7 @@
 
 **Decided to keep as-is:**
 - Multiple Workers with Different Code: Core-only (conceptual explanation sufficient)
-- Heartbeating: Py/TS/Go-only (language-specific code examples, no Core conceptual section needed)
+- Heartbeating: Py/TS/Ruby/Go-only (language-specific code examples, no Core conceptual section needed)
 
 **Intentionally missing (`—`):**
 - Idempotency, Replay Safety, Query Handlers, Error Handling, Retry Policies, Payload Size Limits: Core-only (conceptual)
@@ -53,11 +64,12 @@
 - File Organization: Core + Python; TS covers similar in Activity Imports; Go has simpler package model
 - Activity Imports: TS-specific (bundling/sandbox concerns)
 - Bundling Issues: TS-specific (workflow bundling)
-- Async vs Sync Activities: Python-specific
+- Async vs Sync Activities: Python-specific (Ruby activities run in executors but this is less of a gotcha)
+- Illegal Call Tracing Gotchas: Ruby-specific
 
 **Order alignment:** N/A — Core has conceptual sections, language files have implementation-specific sections
 
-**Style alignment:** ✅ Complete (Python, TypeScript)
+**Style alignment:** ✅ Complete (Python, TypeScript, Go). Ruby: ~7 sections planned.
 - Core: 10 conceptual sections with symptoms/fixes
 - TypeScript: 7 sections (Activity Imports, Bundling, Cancellation, Heartbeating, Testing, Timers, Wrong Retry Classification)
 - Python: 7 sections (File Organization, Async vs Sync, Wrong Retry Classification, Cancellation, Heartbeating, Testing, Timers and Sleep)
diff --git a/.memory/alignment_checking/language.md b/.memory/alignment_checking/language.md
index 2ab9ecc..f07d35d 100644
--- a/.memory/alignment_checking/language.md
+++ b/.memory/alignment_checking/language.md
@@ -4,18 +4,18 @@ Tracks alignment for `python.md`, `typescript.md`, `go.md`, etc.
 
 ## Section Inventory
 
-| Section | Core | Python | Py# | TypeScript | TS# | Go | Go# |
-|---------|------|--------|-----|------------|-----|-----|-----|
-| Overview | — | ✓ | 1 | ✓ | 1 | ✓ | 1 |
-| How Temporal Works: History Replay | — | — | — | — | — | — | — |
-| Understanding Replay | — | — | — | ✓ | 2 | — | — |
-| Quick Start / Quick Demo | — | ✓ | 2 | ✓ | 3 | ✓ | 2 |
-| Key Concepts | — | ✓ | 3 | ✓ | 4 | ✓ | 3 |
-| File Organization Best Practice | — | ✓ | 4 | ✓ | 5 | ✓ | 4 |
-| Determinism Rules | — | — | — | ✓ | 6 | — | — |
-| Common Pitfalls | — | ✓ | 5 | ✓ | 7 | ✓ | 5 |
-| Writing Tests | — | ✓ | 6 | ✓ | 8 | ✓ | 6 |
-| Additional Resources | — | ✓ | 7 | ✓ | 9 | ✓ | 7 |
+| Section | Core | Python | Py# | TypeScript | TS# | Ruby | Rb# | Go | Go# |
+|---------|------|--------|-----|------------|-----|------|-----|-----|-----|
+| Overview | — | ✓ | 1 | ✓ | 1 | TODO | 1 | ✓ | 1 |
+| How Temporal Works: History Replay | — | — | — | — | — | — | — | — | — |
+| Understanding Replay | — | — | — | ✓ | 2 | — | — | — | — |
+| Quick Start / Quick Demo | — | ✓ | 2 | ✓ | 3 | TODO | 2 | ✓ | 2 |
+| Key Concepts | — | ✓ | 3 | ✓ | 4 | TODO | 3 | ✓ | 3 |
+| File Organization Best Practice | — | ✓ | 4 | ✓ | 5 | TODO | 4 | ✓ | 4 |
+| Determinism Rules | — | — | — | ✓ | 6 | — | — | — | — |
+| Common Pitfalls | — | ✓ | 5 | ✓ | 7 | TODO | 5 | ✓ | 5 |
+| Writing Tests | — | ✓ | 6 | ✓ | 8 | TODO | 6 | ✓ | 6 |
+| Additional Resources | — | ✓ | 7 | ✓ | 9 | TODO | 7 | ✓ | 7 |
 
 ## Style Compliance
 
@@ -23,10 +23,20 @@ Tracks alignment for `python.md`, `typescript.md`, `go.md`, etc.
 |----------|--------|-------|
 | Python | ✓ reference | — |
 | TypeScript | ✓ aligned | Has Understanding Replay, Determinism Rules |
+| Ruby | — | Not started |
 | Go | ✓ aligned | Function-based (no decorators), workflowcheck, struct activities |
 
 ## Status
 
+**Ruby notes:**
+- Overview: gem installation (`gem 'temporalio'`), Ruby 3.3+, macOS/Linux only
+- Quick Start: Full tutorial with activity class, workflow class, worker, client (4 files like Python/TS)
+- Key Concepts: Workflows as classes (`< Temporalio::Workflow::Definition`), Activities as classes (`< Temporalio::Activity::Definition`), `Temporalio::Workflow.execute_activity`, determinism via Illegal Call Tracing
+- File Organization: Ruby class-based approach (one class per file convention)
+- Common Pitfalls: Using `sleep` instead of `Temporalio::Workflow.sleep`, using `Time.now` instead of `Temporalio::Workflow.now`, non-deterministic gems in workflows
+- Writing Tests: minitest with `Temporalio::Testing::WorkflowEnvironment`
+- Additional Resources: ruby.temporal.io API docs, samples-ruby repo, Temporal 101 Ruby course
+
 **Section content notes:**
 - Writing Tests: all languages should be a brief link to `references/<lang>/testing.md`, NOT inline code examples
 
@@ -44,9 +54,9 @@ Tracks alignment for `python.md`, `typescript.md`, `go.md`, etc.
 - Determinism Rules — TS has separate section; Python/Go have subsection in Key Concepts
 - Understanding Replay — TS-specific; Python/Go reference core
 
-**Order alignment:** ✓ Aligned — All languages have similar structure (Overview, Quick Start, Key Concepts, File Organization, Common Pitfalls, Writing Tests, Additional Resources)
+**Order alignment:** ✓ Aligned — Ruby follows Python order (no Understanding Replay or Determinism Rules sections)
 
-**Style alignment:** ✅ Complete (Python, TypeScript)
+**Style alignment:** ✅ Complete (Python, TypeScript, Go). Ruby: ~7 sections planned.
 - Removed "How Temporal Works" from TS (now brief "Understanding Replay" referencing core)
 - Added "File Organization Best Practice" to TS
 - Python Quick Demo and TypeScript Quick Start now match (full tutorial with 4 files, run instructions, expected output)
diff --git a/.memory/alignment_checking/observability.md b/.memory/alignment_checking/observability.md
index 3d56a89..7926e38 100644
--- a/.memory/alignment_checking/observability.md
+++ b/.memory/alignment_checking/observability.md
@@ -2,16 +2,16 @@
 
 ## Section Inventory
 
-| Section | Core | Python | Py# | TypeScript | TS# | Go | Go# |
-|---------|------|--------|-----|------------|-----|-----|-----|
-| Overview | — | ✓ | 1 | ✓ | 1 | ✓ | 1 |
-| Logging / Replay-Aware Logging | — | ✓ | 2 | ✓ | 2 | ✓ | 2 |
-| Customizing the Logger | — | ✓ | 2 | ✓ | 3 | ✓ | 3 |
-| OpenTelemetry Integration | — | — | — | — | — | — | — |
-| Metrics | — | ✓ | 3 | ✓ | 4 | ✓ | 4 |
-| Search Attributes (Visibility) | — | ✓ | 4 | — | — | ✓ | 5 |
-| Debugging with Event History | — | — | — | — | — | — | — |
-| Best Practices | — | ✓ | 5 | ✓ | 5 | ✓ | 6 |
+| Section | Core | Python | Py# | TypeScript | TS# | Ruby | Rb# | Go | Go# |
+|---------|------|--------|-----|------------|-----|------|-----|-----|-----|
+| Overview | — | ✓ | 1 | ✓ | 1 | TODO | 1 | ✓ | 1 |
+| Logging / Replay-Aware Logging | — | ✓ | 2 | ✓ | 2 | TODO | 2 | ✓ | 2 |
+| Customizing the Logger | — | ✓ | 2 | ✓ | 3 | — | — | ✓ | 3 |
+| OpenTelemetry Integration | — | — | — | — | — | — | — | — | — |
+| Metrics | — | ✓ | 3 | ✓ | 4 | TODO | 3 | ✓ | 4 |
+| Search Attributes (Visibility) | — | ✓ | 4 | — | — | — | — | ✓ | 5 |
+| Debugging with Event History | — | — | — | — | — | — | — | — | — |
+| Best Practices | — | ✓ | 5 | ✓ | 5 | TODO | 4 | ✓ | 6 |
 
 ## Style Compliance
 
@@ -19,10 +19,18 @@
 |----------|--------|-------|
 | Python | ✓ reference | — |
 | TypeScript | ✓ aligned | Removed verbose sections |
+| Ruby | — | Not started |
 | Go | ✓ aligned | workflow.GetLogger, slog integration, Tally/Prometheus metrics |
 
 ## Status
 
+**Ruby notes:**
+- Logging: `Temporalio::Workflow.logger` is replay-aware; `Temporalio::Activity::Context.current.logger` for activities
+- Metrics: `Temporalio::Runtime::MetricsOptions` with Prometheus (`PrometheusMetricsOptions`) or custom `MetricBuffer`
+- OpenTelemetry: `Temporalio::Contrib::OpenTelemetry::TracingInterceptor` — mentioned inline, not separate section (matching Python/TS style)
+- Ruby has Unsafe.replaying? for side-effect guards: `unless Temporalio::Workflow::Unsafe.replaying?`
+- Customizing the Logger: Ruby's `Temporalio::Workflow.logger` is straightforward; mention inline in Logging section (no separate section)
+
 **Go-specific notes:**
 - Logging: `workflow.GetLogger(ctx)` for replay-safe workflow logging; `activity.GetLogger(ctx)` for activity logging
 - Customizing: Go 1.21+ supports `log.NewStructuredLogger(slog.New(...))` via `client.Options.Logger`; also supports custom `log.Logger` interface
@@ -35,6 +43,6 @@
 - OpenTelemetry / Debugging: Removed as too detailed
 - Search Attributes: Python/Go include; TS keeps in data-handling.md
 
-**Order alignment:** ✓ Aligned — Go# monotonically increases
+**Order alignment:** ✓ Aligned — Ruby follows Python order (compact, 4 sections)
 
-**Style alignment:** ✅ Complete (Python, TypeScript)
+**Style alignment:** ✅ Complete (Python, TypeScript, Go). Ruby should follow same concise structure.
diff --git a/.memory/alignment_checking/patterns.md b/.memory/alignment_checking/patterns.md
index 9485753..5224ea7 100644
--- a/.memory/alignment_checking/patterns.md
+++ b/.memory/alignment_checking/patterns.md
@@ -2,35 +2,37 @@
 
 ## Section Inventory
 
-| Section | Core | Python | Py# | TypeScript | TS# | Go | Go# |
-|---------|------|--------|-----|------------|-----|-----|-----|
-| Signals | ✓ | ✓ | 1 | ✓ | 1 | ✓ | 1 |
-| Dynamic Signal Handlers | — | ✓ | 2 | ✓ | 2 | — | — |
-| Queries | ✓ | ✓ | 3 | ✓ | 3 | ✓ | 2 |
-| Dynamic Query Handlers | — | ✓ | 4 | ✓ | 4 | — | — |
-| Updates | ✓ | ✓ | 5 | ✓ | 5 | ✓ | 3 |
-| Child Workflows | ✓ | ✓ | 6 | ✓ | 6 | ✓ | 4 |
-| Child Workflow Options | — | — | — | ✓ | 7 | ✓ | 4s |
-| Handles to External Workflows | — | ✓ | 7 | ✓ | 8 | ✓ | 5 |
-| Parallel Execution | ✓ | ✓ | 8 | ✓ | 9 | ✓ | 6 |
-| Deterministic Asyncio Alternatives | — | ✓ | 9 | — | — | — | — |
-| Selector Pattern | — | — | — | — | — | ✓ | 7 |
-| Continue-as-New | ✓ | ✓ | 10 | ✓ | 10 | ✓ | 8 |
-| Cancellation Handling (asyncio) | — | ✓ | 12 | — | — | — | — |
-| Cancellation Scopes | — | — | — | ✓ | 12 | — | — |
-| Cancellation Handling | — | — | — | — | — | ✓ | 9 |
-| Saga Pattern | ✓ | ✓ | 11 | ✓ | 11 | ✓ | 10 |
-| Triggers | — | — | — | ✓ | 13 | — | — |
-| Wait Condition with Timeout | — | ✓ | 13 | ✓ | 14 | ✓ | 11 |
-| Waiting for All Handlers to Finish | — | ✓ | 14 | ✓ | 15 | ✓ | 12 |
-| Activity Heartbeat Details | ✓ | ✓ | 15 | ✓ | 16 | ✓ | 13 |
-| Timers | ✓ | ✓ | 16 | ✓ | 17 | ✓ | 14 |
-| Large Data Handling | ✓ | — | — | — | — | — | — |
-| Local Activities | ✓ | ✓ | 17 | ✓ | 18 | ✓ | 15 |
-| Entity Workflow Pattern | ✓ | — | — | — | — | — | — |
-| Polling Patterns | ✓ | — | — | — | — | — | — |
-| Idempotency Patterns | ✓ | — | — | — | — | — | — |
-| Using Pydantic Models | — | ✓ | 18 | — | — | — | — |
+| Section | Core | Python | Py# | TypeScript | TS# | Ruby | Rb# | Go | Go# |
+|---------|------|--------|-----|------------|-----|------|-----|-----|-----|
+| Signals | ✓ | ✓ | 1 | ✓ | 1 | TODO | 1 | ✓ | 1 |
+| Dynamic Signal Handlers | — | ✓ | 2 | ✓ | 2 | TODO | 2 | — | — |
+| Queries | ✓ | ✓ | 3 | ✓ | 3 | TODO | 3 | ✓ | 2 |
+| Dynamic Query Handlers | — | ✓ | 4 | ✓ | 4 | TODO | 4 | — | — |
+| Updates | ✓ | ✓ | 5 | ✓ | 5 | TODO | 5 | ✓ | 3 |
+| Child Workflows | ✓ | ✓ | 6 | ✓ | 6 | TODO | 6 | ✓ | 4 |
+| Child Workflow Options | — | — | — | ✓ | 7 | TODO | 7 | ✓ | 4s |
+| Handles to External Workflows | — | ✓ | 7 | ✓ | 8 | TODO | 8 | ✓ | 5 |
+| Parallel Execution | ✓ | ✓ | 8 | ✓ | 9 | TODO | 9 | ✓ | 6 |
+| Deterministic Asyncio Alternatives | — | ✓ | 9 | — | — | — | — | — | — |
+| Selector Pattern | — | — | — | — | — | — | — | ✓ | 7 |
+| Continue-as-New | ✓ | ✓ | 10 | ✓ | 10 | TODO | 10 | ✓ | 8 |
+| Cancellation Handling (asyncio) | — | ✓ | 12 | — | — | — | — | — | — |
+| Cancellation Scopes | — | — | — | ✓ | 12 | — | — | — | — |
+| Cancellation (Token-based) | — | — | — | — | — | TODO | 12 | — | — |
+| Cancellation Handling | — | — | — | — | — | — | — | ✓ | 9 |
+| Saga Pattern | ✓ | ✓ | 11 | ✓ | 11 | TODO | 11 | ✓ | 10 |
+| Triggers | — | — | — | ✓ | 13 | — | — | — | — |
+| Wait Condition with Timeout | — | ✓ | 13 | ✓ | 14 | TODO | 13 | ✓ | 11 |
+| Waiting for All Handlers to Finish | — | ✓ | 14 | ✓ | 15 | TODO | 14 | ✓ | 12 |
+| Activity Heartbeat Details | ✓ | ✓ | 15 | ✓ | 16 | TODO | 15 | ✓ | 13 |
+| Timers | ✓ | ✓ | 16 | ✓ | 17 | TODO | 16 | ✓ | 14 |
+| Large Data Handling | ✓ | — | — | — | — | — | — | — | — |
+| Local Activities | ✓ | ✓ | 17 | ✓ | 18 | TODO | 17 | ✓ | 15 |
+| Entity Workflow Pattern | ✓ | — | — | — | — | — | — | — | — |
+| Polling Patterns | ✓ | — | — | — | — | — | — | — | — |
+| Idempotency Patterns | ✓ | — | — | — | — | — | — | — | — |
+| Using Pydantic Models | — | ✓ | 18 | — | — | — | — | — | — |
+| Using ActiveModel | — | — | — | — | — | TODO | 18 | — | — |
 
 ## Style Compliance
 
@@ -38,10 +40,21 @@
 |----------|--------|-------|
 | Python | ✓ reference | — |
 | TypeScript | ✓ aligned | Uses `log`, CancellationScope idiom |
+| Ruby | — | Not started |
 | Go | ✓ aligned | Channel-based signals, SetQueryHandler, SetUpdateHandler, Selector, compensation slice saga |
 
 ## Status
 
+**Ruby notes:**
+- Ruby uses `workflow_signal`, `workflow_query`, `workflow_update` class methods (not decorators)
+- Entry point is `def execute` — no annotation needed (unlike Python's `@workflow.run`)
+- Dynamic handlers use `dynamic: true` parameter
+- Parallel execution uses `Temporalio::Workflow::Future.all_of` (not Promise.all or asyncio.gather)
+- Continue-as-New raises `Temporalio::Workflow::ContinueAsNewError` (not a function call)
+- Cancellation uses token-based `Temporalio::Cancellation` objects, similar to .NET — not scope-based (TS) or exception-based (Python)
+- Child Workflow Options: Ruby has `parent_close_policy`, `cancellation_type` as params on `execute_child_workflow`/`start_child_workflow`
+- `workflow_query_attr_reader` shorthand can be mentioned in Queries section
+
 **Cross-language notes:**
 - **Updates — Validator constraints:** All languages (core, Python, TS, Go) now document that validators must NOT mutate state or block (read-only, like query handlers). Added in PR #38 review.
 - Cancellation Handling reordered before Saga in Go (Go# 9→10) so `NewDisconnectedContext` is introduced before Saga uses it
@@ -77,11 +90,16 @@
 - Cancellation Handling vs Cancellation Scopes: different idioms per language
 - Triggers: TS-specific pattern
 - Entity Workflow Pattern: conceptual in core, implementation left to user
+- Deterministic Asyncio Alternatives: Python-specific (TS/Ruby don't have this issue)
+- Cancellation (Token-based): Ruby-specific (uses `Temporalio::Cancellation` token objects)
+- Cancellation Scopes: TS-specific (uses `CancellationScope`)
+- Triggers: TS-specific pattern
 - Using Pydantic Models: Python-specific
+- Using ActiveModel: Ruby-specific (equivalent of Pydantic)
 
-**Order alignment:** ✓ Aligned — TS# and Go# monotonically increase
+**Order alignment:** ✓ Aligned — TS#, Rb#, and Go# monotonically increase
 
-**Style alignment:** ✅ All issues fixed (Python, TypeScript, Go)
+**Style alignment:** ✅ All issues fixed (Python, TypeScript, Go). Ruby: ~18 sections planned.
 - ✅ **Queries:** TS now has "Important: must NOT modify state" note
 - ✅ **Updates:** All languages now have "validators must NOT mutate state or block" note
 - ✅ **Saga Pattern:** TS now has idempotency note, comments about saving compensation BEFORE activity
diff --git a/.memory/alignment_checking/testing.md b/.memory/alignment_checking/testing.md
index 500f07a..c4b7a4b 100644
--- a/.memory/alignment_checking/testing.md
+++ b/.memory/alignment_checking/testing.md
@@ -2,17 +2,17 @@
 
 ## Section Inventory
 
-| Section | Core | Python | Py# | TypeScript | TS# | Go | Go# |
-|---------|------|--------|-----|------------|-----|-----|-----|
-| Overview | — | ✓ | 1 | ✓ | 1 | ✓ | 1 |
-| Test Environment Setup | — | ✓ | 2 | ✓ | 2 | ✓ | 2 |
-| Time Skipping | — | — | — | — | — | — | — |
-| Activity Mocking | — | ✓ | 3 | ✓ | 3 | ✓ | 3 |
-| Testing Signals and Queries | — | ✓ | 4 | ✓ | 4 | ✓ | 4 |
-| Testing Failure Cases | — | ✓ | 5 | ✓ | 5 | ✓ | 5 |
-| Replay Testing | — | ✓ | 6 | ✓ | 6 | ✓ | 6 |
-| Activity Testing | — | ✓ | 7 | ✓ | 7 | ✓ | 7 |
-| Best Practices | — | ✓ | 8 | ✓ | 8 | ✓ | 8 |
+| Section | Core | Python | Py# | TypeScript | TS# | Ruby | Rb# | Go | Go# |
+|---------|------|--------|-----|------------|-----|------|-----|-----|-----|
+| Overview | — | ✓ | 1 | ✓ | 1 | TODO | 1 | ✓ | 1 |
+| Test Environment Setup | — | ✓ | 2 | ✓ | 2 | TODO | 2 | ✓ | 2 |
+| Time Skipping | — | — | — | — | — | — | — | — | — |
+| Activity Mocking | — | ✓ | 3 | ✓ | 3 | TODO | 3 | ✓ | 3 |
+| Testing Signals and Queries | — | ✓ | 4 | ✓ | 4 | TODO | 4 | ✓ | 4 |
+| Testing Failure Cases | — | ✓ | 5 | ✓ | 5 | TODO | 5 | ✓ | 5 |
+| Replay Testing | — | ✓ | 6 | ✓ | 6 | TODO | 6 | ✓ | 6 |
+| Activity Testing | — | ✓ | 7 | ✓ | 7 | TODO | 7 | ✓ | 7 |
+| Best Practices | — | ✓ | 8 | ✓ | 8 | TODO | 8 | ✓ | 8 |
 
 ## Style Compliance
 
@@ -20,10 +20,19 @@
 |----------|--------|-------|
 | Python | ✓ reference | — |
 | TypeScript | ✓ aligned | Added failure/activity testing |
+| Ruby | — | Not started |
 | Go | ✓ aligned | testsuite package, testify, mock activities, TestWorkflowEnvironment |
 
 ## Status
 
+**Ruby notes:**
+- Test Environment: `Temporalio::Testing::WorkflowEnvironment.start_local` (same dev server as other SDKs)
+- Activity Mocking: Write fake activity classes with `activity_name :RealActivityName` to override
+- Activity Testing: `Temporalio::Testing::ActivityEnvironment` for isolated activity tests
+- Replay Testing: `Temporalio::Worker::WorkflowReplayer` with `replay_workflow`/`replay_workflows`
+- Compatible with any test framework (minitest commonly used in samples)
+- Ruby uses `Temporalio::Worker::WorkflowExecutor::ThreadPool.default` for test workers
+
 **Go-specific notes:**
 - Test Environment: `testsuite.WorkflowTestSuite` + `testsuite.TestWorkflowEnvironment` from `go.temporal.io/sdk/testsuite`
 - Uses testify library (`suite.Suite`, `assert`, `mock`)
@@ -39,6 +48,6 @@
 - Core column: no core testing.md exists (implementation-specific)
 - Time Skipping: mentioned inline (built into test environment)
 
-**Order alignment:** ✅ Aligned — Go sections match Python/TypeScript order
+**Order alignment:** ✅ Aligned — Ruby and Go sections match Python/TypeScript order
 
-**Style alignment:** ✅ Complete (Python, TypeScript)
+**Style alignment:** ✅ Complete (Python, TypeScript, Go). Ruby should follow same 8-section structure.
diff --git a/.memory/alignment_checking/versioning.md b/.memory/alignment_checking/versioning.md
index 3df1f60..9f3c15c 100644
--- a/.memory/alignment_checking/versioning.md
+++ b/.memory/alignment_checking/versioning.md
@@ -2,17 +2,17 @@
 
 ## Section Inventory
 
-| Section | Core | Core# | Python | Py# | TypeScript | TS# | Go | Go# |
-|---------|------|-------|--------|-----|------------|-----|-----|-----|
-| Overview | ✓ | 1 | — | — | — | — | — | — |
-| Why Versioning is Needed | ✓ | 2 | — | — | — | — | — | — |
-| Patching API / GetVersion API | ✓ | 3 | ✓ | 1 | ✓ | 1 | ✓ | 1 |
-| Workflow Type Versioning | ✓ | 4 | ✓ | 2 | ✓ | 2 | ✓ | 2 |
-| Worker Versioning | ✓ | 5 | ✓ | 3 | ✓ | 3 | ✓ | 3 |
-| Choosing a Strategy | ✓ | 6 | — | — | — | — | — | — |
-| Best Practices | ✓ | 7 | ✓ | 4 | ✓ | 4 | ✓ | 4 |
-| Finding Workflows by Version | ✓ | 8 | — | — | — | — | — | — |
-| Common Mistakes | ✓ | 9 | — | — | — | — | — | — |
+| Section | Core | Core# | Python | Py# | TypeScript | TS# | Ruby | Rb# | Go | Go# |
+|---------|------|-------|--------|-----|------------|-----|------|-----|-----|-----|
+| Overview | ✓ | 1 | — | — | — | — | — | — | — | — |
+| Why Versioning is Needed | ✓ | 2 | — | — | — | — | — | — | — | — |
+| Patching API / GetVersion API | ✓ | 3 | ✓ | 1 | ✓ | 1 | TODO | 1 | ✓ | 1 |
+| Workflow Type Versioning | ✓ | 4 | ✓ | 2 | ✓ | 2 | TODO | 2 | ✓ | 2 |
+| Worker Versioning | ✓ | 5 | ✓ | 3 | ✓ | 3 | TODO | 3 | ✓ | 3 |
+| Choosing a Strategy | ✓ | 6 | — | — | — | — | — | — | — | — |
+| Best Practices | ✓ | 7 | ✓ | 4 | ✓ | 4 | TODO | 4 | ✓ | 4 |
+| Finding Workflows by Version | ✓ | 8 | — | — | — | — | — | — | — | — |
+| Common Mistakes | ✓ | 9 | — | — | — | — | — | — | — | — |
 
 ## Style Compliance
 
@@ -21,10 +21,16 @@
 | Core | ✓ reference | Conceptual content |
 | Python | ✓ aligned | Code only, refs core |
 | TypeScript | ✓ aligned | Code only, refs core |
+| Ruby | — | Not started |
 | Go | ✓ aligned | Uses `workflow.GetVersion` (not patching); code only, refs core |
 
 ## Status
 
+**Ruby notes:**
+- Patching: `Temporalio::Workflow.patched('my-patch')` and `Temporalio::Workflow.deprecate_patch('my-patch')`
+- Workflow Type Versioning: Standard class duplication pattern (e.g., `MyWorkflowV2 < Temporalio::Workflow::Definition`)
+- Worker Versioning: Supported in Ruby SDK v0.5.0+ with `versioning_behavior:` on workflow definition
+
 **Go-specific notes:**
 - Go uses `workflow.GetVersion(ctx, changeID, minSupported, maxSupported)` — returns a `Version` (int)
 - Different from Python/TS `patched()`/`deprecatePatch()` — Go uses a version number approach
@@ -43,4 +49,4 @@
 
 **Order alignment:** ✓ Aligned — languages focus on code: Patching/GetVersion API, Type Versioning, Worker Versioning, Best Practices
 
-**Style alignment:** ✅ Complete (Python, TypeScript)
+**Style alignment:** ✅ Complete (Python, TypeScript, Go). Ruby: ~4 sections planned.
diff --git a/.memory/correctness_checking/README.md b/.memory/correctness_checking/README.md
index 98f0cac..1e18b41 100644
--- a/.memory/correctness_checking/README.md
+++ b/.memory/correctness_checking/README.md
@@ -9,27 +9,27 @@ Track verification of factual statements and code examples in reference files fo
 
 Each file in this directory tracks correctness for a corresponding reference file. Within each file, sections are organized by language (e.g., `## TypeScript`, `## Python`).
 
-**Supported languages:** TypeScript, Python, Go
+**Supported languages:** TypeScript, Python, Ruby, Go
 
 **Adding a new language:** Add a new `## {Language}` section to each relevant file with a Tracking table and Detailed Notes.
 
 ## Summary
 
-| File | TypeScript | Python | Go |
-|------|------------|--------|-----|
-| patterns.md | ✅ | partial | ✅ |
-| testing.md | ✅ | partial | ✅ |
-| language.md | ✅ | partial | ✅ |
-| versioning.md | ✅ | partial | ✅ |
-| advanced-features.md | ✅ | partial | ✅ |
-| data-handling.md | ✅ | partial | ✅ |
-| determinism-protection.md | ✅ | partial | ✅ |
-| determinism.md | ✅ | partial | ✅ |
-| error-handling.md | ✅ | partial | ✅ |
-| gotchas.md | ✅ | partial | ✅ |
-| observability.md | ✅ | partial | ✅ |
-| ai-patterns.md | — | partial | — |
-| sync-vs-async.md | — | ✅ | — |
+| File | TypeScript | Python | Ruby | Go |
+|------|------------|--------|------|-----|
+| patterns.md | ✅ | partial | partial | ✅ |
+| testing.md | ✅ | partial | unchecked | ✅ |
+| language.md | ✅ | partial | partial | ✅ |
+| versioning.md | ✅ | partial | unchecked | ✅ |
+| advanced-features.md | ✅ | partial | unchecked | ✅ |
+| data-handling.md | ✅ | partial | unchecked | ✅ |
+| determinism-protection.md | ✅ | partial | ✅ | ✅ |
+| determinism.md | ✅ | partial | ✅ | ✅ |
+| error-handling.md | ✅ | partial | unchecked | ✅ |
+| gotchas.md | ✅ | partial | ✅ | ✅ |
+| observability.md | ✅ | partial | ✅ | ✅ |
+| ai-patterns.md | — | partial | — | — |
+| sync-vs-async.md | — | ✅ | — | — |
 
 **Legend:** ✅ = all sections verified, partial = some sections need fixes, unchecked = not yet verified, — = N/A
 
diff --git a/.memory/correctness_checking/language.md b/.memory/correctness_checking/language.md
index 7707133..c803a5d 100644
--- a/.memory/correctness_checking/language.md
+++ b/.memory/correctness_checking/language.md
@@ -223,6 +223,45 @@ Correctness verification for `references/{language}/{language}.md` (e.g., typesc
 
 ---
 
+## Ruby
+
+**File:** `references/ruby/ruby.md` (relative to skill root)
+
+### Tracking
+
+| # | Section | Status | Fix Applied | Sources |
+|---|---------|--------|-------------|---------|
+| 1 | Overview | all good | | sdk-ruby README |
+| 2 | Quick Demo | FIXED | Added 'default' namespace to Client.connect | sdk-ruby README |
+| 3 | Key Concepts | all good | | sdk-ruby README |
+| 4 | File Organization | all good | | N/A |
+| 5 | Common Pitfalls | all good | | N/A |
+| 6 | Writing Tests | all good | | cross-reference |
+| 7 | Additional Resources | all good | | cross-reference |
+
+### Detailed Notes
+
+#### 2. Quick Demo
+**Status:** needs fixes
+
+**Issue:** `Temporalio::Client.connect('localhost:7233')` is missing the namespace argument. The SDK README and all official examples include namespace as the second positional argument.
+
+**Before:**
+```ruby
+client = Temporalio::Client.connect('localhost:7233')
+```
+
+**After:**
+```ruby
+client = Temporalio::Client.connect('localhost:7233', 'default')
+```
+
+This appears twice in ruby.md (worker.rb and execute_workflow.rb examples).
+
+**Source:** sdk-ruby README: `Temporalio::Client.connect('localhost:7233', 'my-namespace')`
+
+---
+
 
 ## Go
 
diff --git a/.memory/correctness_checking/patterns.md b/.memory/correctness_checking/patterns.md
index 1500eba..348d2ba 100644
--- a/.memory/correctness_checking/patterns.md
+++ b/.memory/correctness_checking/patterns.md
@@ -553,6 +553,73 @@ import { proxyLocalActivities } from '@temporalio/workflow';
 
 ---
 
+## Ruby
+
+**File:** `references/ruby/patterns.md` (relative to skill root)
+
+### Tracking
+
+| # | Section | Status | Fix Applied | Sources |
+|---|---------|--------|-------------|---------|
+| 1 | Signals | all good | | temporal-docs, sdk-ruby README |
+| 2 | Dynamic Signal Handlers | all good | | temporal-docs message-passing |
+| 3 | Queries | all good | | sdk-ruby README (workflow_query_attr_reader) |
+| 4 | Dynamic Query Handlers | all good | | temporal-docs message-passing |
+| 5 | Updates | all good | | temporal-docs message-passing |
+| 6 | Child Workflows | all good | | temporal-docs child-workflows, ruby.temporal.io |
+| 7 | Child Workflow Options | all good | | ruby.temporal.io start_child_workflow API |
+| 8 | Handles to External Workflows | FIXED | Fixed signal call to use class method ref | temporal-docs message-passing |
+| 9 | Parallel Execution | all good | | temporal blog (crash-proof fibers), Slack |
+| 10 | Continue-as-New | all good | | temporal-docs continue-as-new |
+| 11 | Saga Pattern | all good | | standard pattern, matches Python |
+| 12 | Cancellation (Token-based) | all good | | sdk-ruby README (Fiber Scheduling and Cancellation) |
+| 13 | Wait Condition with Timeout | all good | | sdk-ruby README (Timers and Conditions) |
+| 14 | Waiting for All Handlers to Finish | FIXED | Added ? suffix to all_handlers_finished | ruby.temporal.io API reference |
+| 15 | Activity Heartbeat Details | all good | | temporal-docs failure-detection, sdk-ruby README |
+| 16 | Timers | all good | | sdk-ruby README |
+| 17 | Local Activities | all good | | ruby.temporal.io execute_local_activity API |
+| 18 | Using ActiveModel | all good | | cross-reference to data-handling.md |
+
+### Detailed Notes
+
+#### 8. Handles to External Workflows
+**Status:** needs fixes
+
+**Issue:** Signal call on external handle uses wrong syntax. Currently passes workflow class and symbol separately.
+
+**Before:**
+```ruby
+handle.signal(TargetWorkflow, :data_ready, data_payload)
+```
+
+**After:**
+```ruby
+handle.signal(TargetWorkflow.data_ready, data_payload)
+```
+
+**Source:** temporal-docs message-passing docs show `handle.signal(WorkflowA.some_signal, 'some signal arg')` — the signal method takes a signal definition (class method generated by `workflow_signal`) as the first argument, not the workflow class.
+
+---
+
+#### 14. Waiting for All Handlers to Finish
+**Status:** needs fixes
+
+**Issue:** Method name missing Ruby boolean `?` suffix. The API reference at ruby.temporal.io lists it as `all_handlers_finished?`.
+
+**Before:**
+```ruby
+Temporalio::Workflow.wait_condition { Temporalio::Workflow.all_handlers_finished }
+```
+
+**After:**
+```ruby
+Temporalio::Workflow.wait_condition { Temporalio::Workflow.all_handlers_finished? }
+```
+
+**Source:** ruby.temporal.io Temporalio::Workflow class method summary
+
+---
+
 
 ## Go