docs: add Show HN announcement post draft

Ready-to-publish HN announcement covering:
- Spec-first development pitch (spec-code drift problem)
- 5-artifact compilation (TS, WASM, PROV-O, CycloneDX, SPDX)
- Example suite: ToggleSwitch → Raft, TLA+ comparison table
- Tech stack, roadmap, publishing tips

Content asset for HN, Reddit, Dev.to distribution

docs/show-hn-announcement.md

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+# Show HN: Speckl — Spec-first development with compilable state machines (open source)
+
+**Title (Show HN):** Show HN: Speckl — Write specs like TLA+, compile to runnable TypeScript and WASM
+
+## Post Body
+
+I built Speckl because I was tired of writing specifications that rot in a wiki while the code drifts in a different direction.
+
+**What it is:** Speckl is a spec-first development tool. You write your system's behavior in SpeckDL (a lightweight specification language) and the compiler generates five artifacts:
+
+1. **TypeScript** — Runnable state machine classes (passes `tsc --noEmit`)
+2. **WASM** — WebAssembly modules with verified state transitions
+3. **PROV-O** — Machine-readable provenance (audit trail)
+4. **CycloneDX SBOM** — Software bill of materials
+5. **SPDX SBOM** — Standardized license/supply chain manifest
+
+**The key insight:** A spec shouldn't just describe what your system does — it should *compile into the thing that does it*. When the spec IS the source of truth, you can't have spec-code drift.
+
+## How it works
+
+Here's a simple toggle switch in SpeckDL:
+
+```
+spec ToggleSwitch
+type State = enum { on, off }
+state active: State = off
+
+init
+  active := off
+
+action flip
+  require active == off
+  active := on
+
+invariant Mutex
+  active == on implies prev(active) == off
+```
+
+The compiler generates a TypeScript class with typed guards, a WASM module with verified state transitions, and provenance metadata proving where every line came from.
+
+## Real specs that compile
+
+The example suite covers:
+
+- **ToggleSwitch** — State machines 101
+- **AccountLedger** — Financial invariants, Map/Set types, audit trails  
+- **TwoPhaseCommit** — Multi-role distributed protocols (direct TLA+ port)
+- **Paxos** — Classic consensus with proposers/acceptors/learners
+- **Raft** — Full Raft protocol: leader election, log replication, 3 safety invariants (Leader Completeness, Log Matching, Single Leader)
+- **TigerBeetleLedger** — Naive port of TigerBeetle's core accounting engine
+
+All 10 examples compile to all 5 artifacts. 41 tests, all passing.
+
+## Why this matters
+
+The gap between "what we specified" and "what we built" is where production bugs live. TLA+ is brilliant for formal verification, but it stops at the model. SpeckDL starts at the model and compiles forward into production code.
+
+| TLA+ | SpeckDL |
+|------|---------|
+| Mathematical modeling | Compilable specifications |
+| TLC model checker | WASM runtime verification |
+| LaTeX pretty-printing | TypeScript production code |
+| Academic/Amazon use | CI/CD integration target |
+
+## Tech stack
+
+- Parser: Custom recursive descent (TypeScript, ~800 lines)
+- Generators: TypeScript state machine, WASM (WAT text format), PROV-O (RDF/Turtle), CycloneDX JSON, SPDX JSON
+- Build: TypeScript → Node.js CLI, `tsc --noEmit` clean
+- Tests: 41 unit tests via Node test runner
+- License: MIT
+
+## What's next
+
+- Parser support for `precondition:` / `postcondition:` declarative assertions
+- Record type emission for generated TypeScript
+- Light JS API for WASM modules
+- Self-spec: The Speckl compiler, specified in SpeckDL
+
+## Try it
+
+- **Repo:** https://os.scoble.me/forgejo/sscoble/speckl
+- **Mirror:** https://codeberg.org/sscoble/speckl
+- **Docs:** https://os.scoble.me/forgejo/sscoble/speckl/src/branch/main/docs/speckl-by-example.md
+- **Website:** https://speckl.scoble.me
+
+Open source (MIT). Looking for feedback, contributors, and early adopters who want to kill spec-code drift.
+
+---
+
+## Publishing notes
+
+**Targets:**
+1. Hacker News (Show HN) — primary
+2. r/programming — secondary (link to HN discussion)
+3. r/rust (TigerBeetle angle) — tertiary
+4. Dev.to — cross-post with full tutorial content
+
+**Best posting times (PT):**
+- HN: Mon-Fri 7-9 AM or 12-2 PM PT
+- Reddit: Tue-Wed 6-9 AM PT
+
+**Posting tips:**
+- Post on HN as "Show HN:" (triggers Show tab placement)
+- First comment: Add context about why this exists + link to tutorial
+- Keep title under 80 chars
+- Don't ask for upvotes
+- Reply to comments within first hour