feat: integrate V-JEPA 2.1 ViT-L/16 as image encoder

.gitignore

@@ -144,6 +144,8 @@ multirun/
 # generated
 config/dataset/*
 config/logger/*
+.claude/
+vjepa2_1_vitl_dist_vitG_384.pt
 
 # editor
 .helix/

CLAUDE.md

@@ -0,0 +1,85 @@
+# rmind × vjepa2.1 integration — agent constraints
+
+These constraints apply to every Claude Code invocation in this repo, interactive
+or headless. They override any conflicting instruction in a prompt.
+
+## Task scope
+
+Two deliverables, in order:
+
+1. **Pre-training encoder integration.** Add vjepa2.1 (ViT-L/16) as an encoder
+   in rmind, mirroring the existing dinov3 image-encoder integration pattern.
+   Determine whether it slots in as the episode encoder, the image encoder, or
+   replaces both — and justify the choice in writing before changing any file.
+
+2. **Fine-tuning config.** A separate YAML/template that loads the pre-trained
+   vjepa2.1 encoder and trains the action-prediction policy on top of it.
+
+## Integration rules
+
+- **YAML/templates first.** New components are wired in via the existing
+  template system (Hydra / OmegaConf / whatever rmind uses — discover it, don't
+  assume). Python code is a last resort.
+- **If Python is necessary**, justify it explicitly in the plan: what YAML
+  feature is missing, why a new module class is required. One paragraph minimum.
+- **Mirror dinov3.** Before writing anything, diff the proposed structure
+  against the dinov3 image-encoder YAML. The new files should look like
+  siblings, not cousins.
+- **Read-only dependencies.** Do not modify source files inside `~/Code/rbyte`
+  or `~/Code/vjepa2`. They are dependencies. If something is broken in them,
+  report it — don't patch it.
+
+## Architectural decision: freezing
+
+- The **vjepa2.1 encoder itself is NOT frozen** during pre-training in rmind.
+- The **dinov3 component *inside* vjepa2.1 IS frozen**. (V-JEPA 2.1 uses a
+  pre-trained DINOv3 as part of its target/teacher pipeline; that part stays
+  frozen.)
+- This means the integration must expose two parameter groups, or set
+  `requires_grad=False` on the dinov3 sub-module specifically. Verify this is
+  achievable from YAML; if not, that's a legitimate reason to add Python.
+
+## Checkpoint
+
+- Use the **ViT-L/16 vjepa2.1** checkpoint. Do not substitute ViT-B, ViT-H,
+  or any other variant without asking.
+- The exact path/URL of the checkpoint is unknown to the agent at the start.
+  Phase 1 must locate it (inside `~/Code/vjepa2`, in a release artifact, or via
+  the paper). If it cannot be located, STOP and ask.
+
+## Open questions the agent must resolve in Phase 1
+
+These are unknowns flagged by the user — do not guess; report findings.
+
+1. Whether "vjepa2.1" lives in the `~/Code/vjepa2` repo (branch, subdir, tag)
+   or somewhere else.
+2. Whether the second paper URL (arXiv 2603.14482) is reachable. The ID looks
+   malformed (the YYMM prefix doesn't parse). If `WebFetch` fails, report it —
+   do not invent the paper's contents.
+3. Whether vjepa2.1 fits the episode-encoder slot, the image-encoder slot, or
+   subsumes both. The user's hypothesis is "both in one go" — verify against
+   the actual rmind interfaces.
+4. Action-prediction policy details for fine-tuning: action space, dataset,
+   loss. If rmind has an existing action-prediction config, reuse its defaults
+   and call them out. If not, STOP and ask.
+
+## Safety rails
+
+- All work on a feature branch: `feat/vjepa2.1-encoder`. Create it before any
+  edit. Never commit to main.
+- Never `git push`. Never `git push --force`. Never `git reset --hard` against
+  anything the user has touched.
+- Never run training. Validation = config loads + one forward pass on dummy
+  tensors of the documented input shape. That's it.
+- Never download model weights without confirming. If a checkpoint isn't on
+  disk, report the URL and stop.
+- Do not modify files outside `~/Code/rmind`.
+
+## Reporting
+
+- Every claim about an existing file must cite `path:line`.
+- The Phase 2 plan is a hard checkpoint. Print it, then stop. Wait for the
+  orchestrator script (or the user) to advance to Phase 3.
+- On completion, produce a summary listing: files added, files edited, Python
+  additions (with justification), config-load validation result, forward-pass
+  validation result.