langchain-id-aliaser

Reversible UUID / ID aliasing for LangChain & LangGraph. Replace long identifiers with short, stable aliases before they reach the LLM — and restore the originals on the way back, including in the model's outgoing tool calls.

f47ac10b-58cc-4372-a567-0e02b2c3d479   →   usr_a9Fk2
        (~15-19 tokens)                        (~2 tokens)

Why

• Cheaper. A UUID tokenizes into ~15-19 tokens. In agent loops the same ids echo through tool calls, results, and state — the cost multiplies. Aliases are 1-2 tokens.
• More accurate. LLMs frequently mangle or hallucinate long UUIDs. Short, stable aliases are far harder to corrupt, so tool calls round-trip correctly.

Install

pip install langchain-id-aliaser            # core only
pip install "langchain-id-aliaser[langchain]"  # + adapters

How it works

One dependency-free engine (IdAliaser) detects ids, aliases them, and restores them. Three thin adapters share that engine so behavior is identical everywhere:

Core

from langchain_id_aliaser import IdAliaser

a = IdAliaser()                       # deterministic-hash mode, UUIDs on by default
a.register(value="cust_8f3k2", type="cust")   # alias any value, with a type prefix
a.register(pattern=r"order_\d+", type="ord")  # ...or a custom pattern

aliased = a.aliasify("user f47ac10b-58cc-4372-a567-0e02b2c3d479 placed order_991")
restored = a.restore(aliased)         # exact inverse; unknown aliases pass through

Single call

from langchain_id_aliaser import wrap_model

model = wrap_model(chat_model)        # alias in, restore out — incl. tool calls
model.invoke(messages)

Agent middleware

from langchain_id_aliaser import AliasMiddleware

agent = create_agent(model, tools, middleware=[AliasMiddleware()])

Raw graph

from langchain_id_aliaser import make_model_node

graph.add_node("model", make_model_node(chat_model))

Options

• mode="hash" (default): deterministic alias from the id — same id → same alias, no stored state, stable across turns. mode="ordinal": id1, id2 … (shorter, but the mapping must be reused to stay consistent).
• strict=True: raise UnknownAliasError when the model emits an alias-shaped token that isn't in the mapping. Default is forgiving (pass through).

License

MIT