Graph paths & policies¶

A model graph is addressable by named paths. Paths make deployment policy a property of the root application instead of a property embedded in model source.

Paths¶

Module and parameter names compose into dot-separated paths:

model.language_model.layers.7.self_attn.q_proj.weight

Because projects can target these names, renaming a public model path is a contract change for manifests that depend on it.

Pattern matching¶

* matches one path segment. A policy path also applies to descendants after its own segments match, which is how inheritance is expressed.

model.layers.*.mlp

matches a descendant such as:

model.layers.7.mlp.down_proj.weight

but not model.layers.mlp.

Root policy¶

The first policy record is the compiler's root policy. The current compiler requires it to exist, define dtype, and provide a scheme that can cover constant + immutable weights.

[policies."model"]
dtype = "f16"

[policies."model".backend]
device = "local"

[[policies."model".schemes]]
scope = "constant"
lifetime = "immutable"
update = "none"
format = "f16"

Merge order¶

For a requested graph path, the compiler:

1. starts with the first/root policy;
2. collects later policy patterns that match;
3. sorts the matches by pattern-string length, shortest first;
4. merges them in that order.

The longest matching pattern therefore applies last. Equal-length patterns keep manifest order because equal-length matches preserve their manifest order.

Field merge¶

A matching child policy only replaces fields it declares. dtype, backend, and optimization_barrier inherit when omitted.

Schemes are merged by the (scope, lifetime) key. Replacing a constant/immutable scheme does not erase a separate session-lifetime scheme inherited from an ancestor.

Scheme selection¶

A scheme has:

Axis	Values
scope	any, constant, input, output, internal
lifetime	any, immutable, invocation, session
update	none, whole, region
volatile	false, true
format	resolved codec export

When wildcard (any) and concrete schemes could both match a concrete scope/lifetime pair, the compiler selects the most specific combination. An ambiguous tie is rejected.

Immutable values require update = "none". volatile = true allows the Runtime to discard their clean package-backed host pages after invocation.

Practical policy layout¶

Keep the default broad and add exceptions only where they are justified:

[policies."model"]
dtype = "f16"

[[policies."model".schemes]]
scope = "constant"
lifetime = "immutable"
update = "none"
format = "f16"

[[policies."model.layers.*.mlp.down_proj.weight".schemes]]
scope = "constant"
lifetime = "immutable"
update = "none"
format = "q4k"

Use synps inspect after changing path rules. It is cheaper and more reliable than discovering a wrong match after a full model build.