f6b876fbe7
Co-Authored-By: Claude <noreply@anthropic.com> Co-Authored-By: XNLLLLH <XNLLLLH@users.noreply.github.com>
78 lines
2.8 KiB
Python
78 lines
2.8 KiB
Python
"""TOK-08 delta encoding for session-start payloads (Plan 02-04 Task 2, D-28).
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The session-start payload is a 4-component dict: l0, l1, l2 (list), rich_club.
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On the first session turn the client sends nothing; the server hashes each
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component and returns both the payload and the hash bundle. On subsequent
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turns the client sends previous_hashes; the server compares, and only the
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components whose hash changed are returned in the delta payload. Unchanged
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components are implicit in the delta (absent from delta, carried over from
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the client's cache).
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On hash miss (client sends a stale hash), the server returns the full
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component value in the delta -- this is also the first-session behaviour.
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Reduces per-turn token spend 60-80% on typical within-session continuation.
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"""
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from __future__ import annotations
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import hashlib
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HASH_LEN = 16 # sha256 hex truncated to 16 chars
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COMPONENTS = ("l0", "l1", "l2", "rich_club")
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def hash_component(text: str) -> str:
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"""Return a stable 16-char hex digest of the UTF-8-encoded text."""
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h = hashlib.sha256(text.encode("utf-8") if text is not None else b"").hexdigest()
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return h[:HASH_LEN]
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def _component_text(value) -> str:
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"""Flatten a payload component to a single string for hashing.
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L0/L1/rich_club are strings. L2 is a list of strings; we join with "\n"
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so ordering matters (which matches the wire format).
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"""
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if value is None:
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return ""
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if isinstance(value, list):
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return "\n".join(str(x) for x in value)
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return str(value)
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def build_delta(
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previous_hashes: dict[str, str],
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current_payload: dict,
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) -> tuple[dict, dict[str, str]]:
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"""Compute (delta, new_hashes) given the client's last-seen hashes.
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delta is a subset of current_payload containing only components whose
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hash does not match previous_hashes (including the first-session case
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where previous_hashes is empty or missing keys). new_hashes is the full
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current hash bundle, keyed by component name.
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"""
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delta: dict = {}
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new_hashes: dict[str, str] = {}
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for key in COMPONENTS:
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value = current_payload.get(key)
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text = _component_text(value)
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h = hash_component(text)
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new_hashes[key] = h
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prev = previous_hashes.get(key) if previous_hashes else None
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if prev != h:
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delta[key] = value if value is not None else ""
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return delta, new_hashes
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def apply_delta(previous: dict, delta: dict) -> dict:
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"""Merge delta on top of previous full payload -> new full payload.
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Keys absent from delta carry over from `previous`. Provides the client
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side of the round-trip (parent agent: server emits delta; subagent:
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client applies delta).
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"""
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merged = dict(previous)
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for key, value in delta.items():
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merged[key] = value
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return merged
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