docs(eeg): define offline encoder boundary and Shadow Lab MVP

[aurascoper]

W0 planning package. Documents, schemas, and contract tests only.

scope: planning_and_contracts_only
application_code_change: false
implementation_authorized: false
model_execution: false
live_control: false
promotion_status: not_eligible
base_is_authoritative: false
future_disposition:
  - rebase_after_branch_convergence
  - or_cherry_pick_e66bd09_and_c814235

Why this base, and why draft

Based on research/eeg-fusion-base because these artifacts extend the D0 fusion
contracts that live only there. That base is not the authoritative baseline:
the branches forked at 3e1b55b, so docs/eeg-methods-scope carries PR #29 but
lacks 16 D0 commits, while this base carries the 16 but lacks the fix. Neither is
a superset.

Left draft and unmerged deliberately — merging would add another layer to an
already-forked staging topology. Its disposition after convergence is a rebase,
or a cherry-pick of e66bd09 and c814235.

Commits

e66bd09	research(eeg): register offline encoder artifact boundary
c814235	docs(eeg): define the EEG Shadow Lab MVP scope

What it decides

Exploration found the intended "runtime integration" is not currently buildable
as such, for structural reasons:

• The packaged app has no Python interpreter — package-app-bundle.sh copies the
  app binary, its dylibs, and SpectralProbe, and no Swift code invokes Python.
• The window contracts disagree: the app windows at 2 s, while contracts.py and
  configs/muse-four-channel-v0.json pin 4 s / 1024 samples and every adapter
  hard-asserts [B, 4, 1024]. Stride agrees at 1 s; the window does not.
• The existing worker protocol is already file handoff across machines. There is
  no IPC or streaming path anywhere in NeuralComposeEEG/.

So ADR-011 records an artifact boundary, not a worker boundary: encoders run
offline and produce immutable provenance-bound artifacts; Swift only imports,
validates, and replays them.

nc-eeg-encoder-state-v0 uses a closed discriminated source union, with top-level
if/then rules making the source type constrain the window clock fields, so a
synthetic fixture and a physical replay are distinguishable and neither validates
as the other. Every record pins 1024 samples and asserts
live_two_second_window_used: false, making the 2 s/4 s boundary a validation
failure rather than a silent pad.

A fusion encoder-output record deliberately does not validate as an encoder
state, and a separate test pins the existing F0–F2 evidence bundle byte-identical
to HEAD — its byte identity is part of its provenance.

ADR-011, not ADR-010: 010 is reserved for the Rust Compute Engine and lives at
docs/architecture/rust-compute-engine/ on research/rust-workspace, outside
decision-log/, so a directory listing reports it as free when it is not. The new
decision-log/README.md registry exists to make that visible, alongside the
ADR-004 duplication and the absent-but-cited ADR-009.

Stages are W0–W7 because P0–P4 is already the policy ladder in
EXP-NC-EEG-FUSION-001; W6/W7 reuse it rather than duplicating it.

Prerequisites named, not worked around

EEGPT's checkpoint_sha256 stays null — a placeholder digest would be worse —
and EEGNet remains absent from the encoder-ID registry. Tests assert both remain
untouched here.

Verification

119 NeuralComposeEEG tests pass (88 pre-existing, 31 new). Fusion artifacts
regenerate byte-identically. Ruff clean. No broken internal links.
git diff --check clean. No Sources/, Package.swift, configs/, Scripts/,
or .github/ file modified — application_code_change: false holds literally.

Note these tests are local-only: CI runs no Python (R9).

🤖 Generated with Claude Code

[aurascoper]

Parked, not rejected. This planning-and-contract package remains preserved at 1251b5b. Integration is tracked in issue #34 and will occur by rebase or selective cherry-pick after the currently divergent EEG branches converge. No application runtime, model execution, live control, or promotion authority is granted.

One correction carried into #34: this PR has three commits, not the two named in the description. 1251b5b ("graduated execution states and fail-closed fusion v1") is the branch head and contributes independently — it adds nc-eeg-fused-state-v1.schema.json and docs/science/predictive-processing-background.md. Any future integration must account for all three.

The branch docs/eeg-offline-encoder-boundary is retained deliberately and must not be deleted until #34 is resolved.