docs(phase0): core generalization steer: one core, three targets

Principal steer: generalize the shared core across HTML generation
(branch 0), Rust codecs (branch 1), and WGSL/wasm-JIT (branch 3
territory); dev-tool emit demoted from the crate's definition to one
projection. Records the core/per-target split and the render-purity
requirement the wasm JIT fixes for Phase 1; refines OQ-GN-09.

docs/research/phase-0.md

@@ -80,6 +80,48 @@ What this adds, and what it changes about the framing:
   revalidated against it (see OQ resolution notes and
   `reader-poc-summary.md`'s re-validation note).
 
+### Core generalization steer (2026-11-06, setup discussion)
+
+Principal steer after the unpause: the shared core should generalize
+across three real targets, with the dev tool (static files into
+downstream projects) demoted from "the product" to a nice-to-have
+projection of the same machinery:
+
+- **HTML generation (branch 0)**: the first and simplest customer.
+  Its value is structural: no plan projection, no layout math, no
+  typed-output machinery. If the core renders HTML cleanly without
+  target-specific exceptions, the codegen paths are not overfitted.
+- **Rust codecs (branch 1)**: the reader POC already showed the
+  branch-specific complexity lives in the context builder (plan
+  projection, OQ-GN-02), not the registry/render layer. That is
+  evidence this split works.
+- **WGSL / the wasm JIT idea (branch 3 territory)**: alkminer-v1's
+  `ShaderBuilder` is the precedent. Since alktype + handlebars are
+  already wasm-clean, a wasm build can carry the render-then-compile
+  cache itself (render as the JIT step at runtime). Far down the
+  timeline, but it fixes one design requirement today: keep partials
+  first-class and keep rendering pure, synchronous, and deterministic
+  so the render step can be cached and compiled downstream. Retrofit
+  cost would be high later, preservation cost now is near zero.
+
+Concretely, the working split for Phase 1:
+
+- **Shared core**: registry construction (strict mode, first-class
+  partials), context conventions, deterministic render entry point,
+  typed errors. Everything wasm-clean, synchronous, allocation-lean.
+- **Per target**: the template set, the context shape (plan-driven
+  projection vs page/data views vs shader contexts), and the emit
+  posture (static files at build time vs in-library render vs
+  render-then-compile feed).
+- **Demoted, not dead**: the dev-tool emit model (OQ-GN-01) stays the
+  shape of branches 1/2's output but is no longer the definition of
+  the crate; the crate is "template rendering over alk-type documents
+  and arbitrary contexts", with targets as template sets plus emit
+  layers.
+
+This refines OQ-GN-09: the SSR branch is not a special case to be
+accommodated; it is the first instantiation and the generality test.
+
 ## What is already settled
 
 - **The stack shape**: handlebars-rust renders templates; alktype
@@ -511,4 +553,7 @@ is a place the compiled path stays interpreter-shaped.
 - [ ] OQ-GN-09 (SSR branch scope, opened 2026-11-06): needs a
       scope/library-posture answer (in-process rendering vs
       pre-rendered, shared-core split) before Phase 1's ADRs; alkforge
-      is the consumer waiting on it
+      is the consumer waiting on it. Refined by the core
+      generalization steer (§"Core generalization steer"): the core
+      split proposal is recorded; the remaining decision is the SSR
+      library posture and the exact core/emit boundary