| """The backend seam. Four questions and two operations, same shape as the |
| timeline package's backend: small enough that a second implementation is a |
| day's work rather than a negotiation. |
| |
| capabilities() what this model can be asked for |
| validate_tap() is this experiment config expressible here |
| fingerprint() what is actually loaded right now |
| plan_arms() how to build a shape-matched control for this model |
| |
| capture() run the forwards, write the evidence |
| compile() realize a plan as native conditioning |
| |
| The last two are where a backend earns its keep and where the first one is |
| still empty. A seam with one implementation and no second in sight is |
| usually a fiction, so this one is deliberately minimal: it declares only |
| what the H3 work actually needs, and the second backend gets to widen it. |
| """ |
| from __future__ import annotations |
|
|
| from concept_lab import types as T |
|
|
|
|
| class BackendError(RuntimeError): |
| pass |
|
|
|
|
| class Backend: |
| name = "base" |
|
|
| |
| def capabilities(self) -> dict: |
| """What this backend supports, as data an agent can branch on.""" |
| raise NotImplementedError |
|
|
| def default_blocks(self) -> tuple: |
| """A first tap ladder. An experiment config, never a format fact.""" |
| raise NotImplementedError |
|
|
| def default_segments(self) -> tuple: |
| """Which named segments a v0 capture should keep.""" |
| raise NotImplementedError |
|
|
| def segment_vocabulary(self) -> tuple: |
| """Every segment name this backend's packed layout can produce.""" |
| raise NotImplementedError |
|
|
| def cost_model(self) -> dict: |
| """How this backend's cost actually scales, as data a planner reads. |
| |
| Forward count is the unit everyone reaches for and it is wrong |
| wherever conditioning changes the packed sequence length. A backend |
| that has measured its own scaling says so here; the default says |
| nothing rather than guessing. |
| """ |
| return {"note": f"{self.name} has not declared a cost model; " |
| f"forward count is the only unit available and it " |
| f"is probably not the right one"} |
|
|
| def validate_tap(self, tap: T.TapSpec) -> None: |
| """Refuse a tap this backend cannot honour, and say which field.""" |
| vocab = self.segment_vocabulary() |
| bad = [s for s in tap.segments if s not in vocab] |
| if bad: |
| raise BackendError( |
| f"{self.name}: unknown segment(s) {bad}; this backend's " |
| f"packed layout has {list(vocab)}") |
|
|
| def fingerprint(self, **kw) -> T.ModelStackFingerprint: |
| """What is loaded, read from the live stack. Never from a filename.""" |
| raise NotImplementedError |
|
|
| def plan_arms(self, source: T.ConditioningSource) -> dict: |
| """How to build the shape-matched control for this source. |
| |
| A structural control is backend-specific because what counts as |
| 'same shape' is: same reference count, same post-preprocess |
| dimensions, same modality, same presentation token length. Getting |
| this wrong is the difference between measuring reference content |
| and measuring that a reference exists. |
| """ |
| raise NotImplementedError |
|
|
| |
| def capture(self, *a, **k): |
| raise NotImplementedError |
|
|
| def compile(self, *a, **k): |
| raise NotImplementedError |
|
|
