docs: README Getting Started, ecosystem, and ownership boundaries (#35)

Deduplicate mission text; add Getting Started (git dep + example),
Ecosystem table, Scope/Ownership (link BOUNDARY_MATRIX / GH#9), and MSRV.

Closes #9
Closes #20

Author: rmems

README.md

@@ -4,19 +4,81 @@
 
 Neuromodulatory reward shaping and RL critic functions for SNNs.
 
-This crate provides a generalized engine that translates any external objective into biological neuromodulator concentrations. Its sole purpose is to compute the scalar values that feed into `neuromod::rm_stdp` (Reward-Modulated STDP).
+## Mission
 
-## Mission: Generic Reward Shaping
+This crate is a generalized engine that translates any external objective into
+biological neuromodulator concentrations. Its sole purpose is to compute the
+scalar values that feed into reward-modulated learning (e.g. `neuromod::rm_stdp`).
 
-This crate is a generalized engine that translates any external objective into biological neuromodulator concentrations.
+**Architecture (condensed):**
 
-Its sole purpose is to compute the scalar values that feed into `neuromod::rm_stdp` (Reward-Modulated STDP).
+* **Environment trait** — abstract interface for any measurable external system
+  (simulation score, trading PnL, LLM loss, etc.)
+* **Reward functions** — temporal difference error, curiosity-driven intrinsic
+  reward, moving-average baselines
+* **Modulator mapping** — maps mathematical errors into constrained `f32`
+  vectors for dopamine (reward), serotonin (risk/volatility), and norepinephrine
+  (stress/telemetry)
 
-### Architecture
+**MSRV:** Rust 1.85 (`rust-version` in `Cargo.toml`).
 
-* **Environment Trait**: Abstract interface via the `Environment` trait. The crate is agnostic to whether it's evaluating a simulation score, a trading bot's PnL, an LLM's cross-entropy loss, or any other performance indicator.
-* **Reward Functions**: Standard RL reward shaping functions — Temporal Difference error, curiosity-driven intrinsic reward, moving-average baselines.
-* **Modulator Mapping**: Maps mathematical errors into constrained `f32` vectors representing Dopamine (reward), Serotonin (risk/volatility), and Norepinephrine (stress/telemetry).
+## Getting Started
+
+Until published on crates.io, depend on the git repository:
+
+```toml
+[dependencies]
+limbic-critic = { git = "https://github.com/Limen-Neural/limbic-critic" }
+```
+
+After publish:
+
+```bash
+cargo add limbic-critic
+```
+
+Run the generic environment example:
+
+```bash
+cargo run --example generic_environment
+```
+
+## Ecosystem
+
+| Layer | Role | Crate / repo |
+|-------|------|----------------|
+| Application | Implements `Environment` for your domain | your app / adapters |
+| **limbic-critic** | Produces local `ModulatorVector` via `SimpleCritic` / `TDCritic` | [limbic-critic](https://github.com/Limen-Neural/limbic-critic) |
+| Bridge | Maps `ModulatorVector` → neuromod `NeuroModulators` | [plasticity-lab](https://github.com/Limen-Neural/plasticity-lab) |
+| Plasticity | Consumes modulators in `rm_stdp` | [neuromod](https://github.com/Limen-Neural/neuromod) |
+
+Sibling crates live under the [Limen-Neural](https://github.com/Limen-Neural)
+organization. This crate does **not** take Cargo dependencies on those
+siblings; integration happens in application or bridge crates.
+
+## Scope and Ownership Boundaries
+
+See the full matrix: [`docs/BOUNDARY_MATRIX.md`](docs/BOUNDARY_MATRIX.md)
+(LIM-9 / [GH#9](https://github.com/Limen-Neural/limbic-critic/issues/9)).
+
+**Owns:**
+
+* Reward shaping and credit-assignment algorithms
+* The `Environment` trait
+* Local `ModulatorVector` output structure
+
+**Does not own:**
+
+* Training loops or SNN model definitions
+* Domain-specific rewards (mining, trading, games)
+* Environment implementations (belong in apps/adapters)
+* Neuromodulator dynamics / decay (upstream SNN crates)
+
+**Forbidden:**
+
+* Inter-repo Cargo dependencies on sibling crates such as `neuromod`,
+  `plasticity-lab`, or other SNN primitives (keeps the crate modular and
+  decoupled)
 
 ## Development
 
@@ -32,7 +94,9 @@ cargo llvm-cov --all-features --lcov --output-path lcov.info
 # HTML report: cargo llvm-cov --all-features --html
 ```
 
-These development commands, hygiene improvements, test assertions, MSRV declaration, artifact cleanup, and Codecov integration were contributed by the following GitHub issues (bundled as beads lc-r97 / PR #28):
+These development commands, hygiene improvements, test assertions, MSRV
+declaration, artifact cleanup, and Codecov integration were contributed by the
+following GitHub issues (bundled as beads lc-r97 / PR #28):
 
 * [GH-16](https://github.com/Limen-Neural/limbic-critic/issues/16): Remove tracked CI log artifacts
 * [GH-17](https://github.com/Limen-Neural/limbic-critic/issues/17): Remove unused serde dependency