diff --git a/litellm/managed_agents/adapters/normalization.py b/litellm/managed_agents/adapters/normalization.py
new file mode 100644
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+++ b/litellm/managed_agents/adapters/normalization.py
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+"""Pure normalization helpers for the opencode adapter.
+
+These functions translate opencode wire shapes into our normalized
+`MessageRow` and SSE event tuples per contract §7. They have NO side
+effects, NO HTTP, NO DB calls — pure dict-in / object-out.
+
+The opencode wire shapes documented in the contract are best-effort. The
+preflight agent (running in parallel) will document the real payload
+shapes; defensive `.get()` access is used everywhere so missing keys
+degrade gracefully instead of raising. Branches that depend on shape
+details we are not 100% sure of are tagged with
+`# TODO: verify against preflight findings`.
+"""
+
+from datetime import datetime
+from typing import Any, Dict, List, Optional, Tuple
+
+from litellm.managed_agents.types import MessageRow
+
+
+# ---------------------------------------------------------------------------
+# Message normalization
+# ---------------------------------------------------------------------------
+
+
+def normalize_opencode_message(
+    opencode_msg: Dict[str, Any],
+    our_session_id: str,
+) -> MessageRow:
+    """Translate one opencode message dict into a MessageRow.
+
+    Rules (contract §7):
+      - `id` passes through from opencode.
+      - `session_id` is OUR `ses_*` id, NEVER opencode's `oc_sid`.
+      - `content` = concat of `text` parts in order.
+      - `tools` = list of `tool` parts (omit if zero).
+      - `status` = "completed" if `completedAt` set, else "in_progress";
+        "failed" if any part has type="error".
+      - `model` from `modelID` or `model` (whichever opencode emits).
+      - timestamps: parse ISO if string, pass through if already datetime.
+    """
+    parts = opencode_msg.get("parts") or []
+
+    text_chunks: List[str] = []
+    tool_calls: List[Dict[str, Any]] = []
+    has_error_part = False
+
+    for part in parts:
+        if not isinstance(part, dict):
+            # TODO: verify against preflight findings — opencode SHOULD always
+            # emit dict parts, but be defensive about non-dicts in the array.
+            continue
+        ptype = part.get("type")
+        if ptype == "text":
+            text = part.get("text")
+            if isinstance(text, str):
+                text_chunks.append(text)
+        elif ptype == "tool":
+            tool_calls.append(
+                {
+                    "name": part.get("name"),
+                    "input": part.get("input"),
+                    "output": part.get("output"),
+                }
+            )
+        elif ptype == "error":
+            has_error_part = True
+        # All other part types (e.g. permission, lsp diagnostics) are ignored.
+        # TODO: verify against preflight findings.
+
+    content = "".join(text_chunks)
+    tools: Optional[List[Dict[str, Any]]] = tool_calls if tool_calls else None
+
+    completed_at_raw = opencode_msg.get("completedAt")
+    if has_error_part:
+        status = "failed"
+    elif completed_at_raw:
+        status = "completed"
+    else:
+        status = "in_progress"
+
+    # opencode field name: prefer `modelID` (camelCase, opencode convention),
+    # fall back to `model` for forward-compat.
+    # TODO: verify against preflight findings.
+    model = opencode_msg.get("modelID") or opencode_msg.get("model")
+
+    created_at_raw = opencode_msg.get("createdAt")
+
+    return MessageRow(
+        id=opencode_msg.get("id", ""),
+        session_id=our_session_id,
+        role=opencode_msg.get("role", "assistant"),
+        content=content,
+        model=model,
+        tools=tools,
+        status=status,  # type: ignore[arg-type]
+        created_at=_parse_ts(created_at_raw) or datetime.utcnow(),
+        completed_at=_parse_ts(completed_at_raw),
+    )
+
+
+# ---------------------------------------------------------------------------
+# Event normalization
+# ---------------------------------------------------------------------------
+
+
+def normalize_opencode_event(
+    raw_event: Dict[str, Any],
+) -> Optional[Tuple[str, Dict[str, Any]]]:
+    """Translate one opencode SSE event dict into our (type, data) tuple.
+
+    Returns None for events we drop (per contract §7 — `permission.updated`,
+    `lsp.client.diagnostics`, etc.). The caller is responsible for filtering
+    by `sessionID` BEFORE invoking this function — this helper only does
+    type-and-shape mapping.
+
+    opencode events come in shapes like:
+      {"type": "message.updated", "properties": {...}}
+      {"type": "message.part.updated", "properties": {"part": {...}, ...}}
+
+    We access `properties` defensively because the exact wrapper shape
+    differs across opencode versions.
+    """
+    if not isinstance(raw_event, dict):
+        return None
+
+    event_type = raw_event.get("type")
+    if not isinstance(event_type, str):
+        return None
+
+    # opencode wraps payload data in `properties` per its event-bus convention.
+    # TODO: verify against preflight findings — some versions may inline the
+    # payload at the top level instead.
+    props = raw_event.get("properties") or {}
+    if not isinstance(props, dict):
+        props = {}
+
+    if event_type == "message.updated":
+        message = props.get("info") or props.get("message") or {}
+        message_id = (
+            message.get("id") if isinstance(message, dict) else None
+        ) or props.get("messageID")
+        role = (
+            message.get("role") if isinstance(message, dict) else None
+        ) or props.get("role")
+        return (
+            "message.started",
+            {"message_id": message_id, "role": role},
+        )
+
+    if event_type == "message.part.updated":
+        part = props.get("part") or {}
+        if not isinstance(part, dict):
+            return None
+        message_id = part.get("messageID") or props.get("messageID")
+        ptype = part.get("type")
+
+        if ptype == "text":
+            # TODO: verify against preflight findings — opencode may emit
+            # cumulative text or only the new delta. We pass through what
+            # the part contains; the SDK handles either case.
+            delta = part.get("text") or part.get("delta") or ""
+            return (
+                "message.text.delta",
+                {"message_id": message_id, "delta": delta},
+            )
+
+        if ptype == "tool":
+            tool_name = part.get("name")
+            output = part.get("output")
+            if output is not None:
+                # Tool finished (has output).
+                return (
+                    "message.tool.completed",
+                    {
+                        "message_id": message_id,
+                        "tool": tool_name,
+                        "output": output,
+                    },
+                )
+            # Tool started (no output yet).
+            # TODO: verify against preflight findings — some opencode
+            # versions use a `state`/`status` field on the tool part to
+            # distinguish start from completion instead of presence of
+            # `output`. We use presence-of-output as the default.
+            return (
+                "message.tool.started",
+                {
+                    "message_id": message_id,
+                    "tool": tool_name,
+                    "input": part.get("input"),
+                },
+            )
+
+        # Other part types (e.g. step-start, file) are dropped.
+        return None
+
+    if event_type == "session.idle":
+        # Turn done — emit `message.completed`. opencode's idle payload may
+        # not always include the message id/content directly; best-effort.
+        # TODO: verify against preflight findings.
+        message_id = props.get("messageID") or props.get("message_id")
+        return (
+            "message.completed",
+            {
+                "message_id": message_id,
+                "content": props.get("content"),
+                "completed_at": props.get("completedAt") or props.get("completed_at"),
+            },
+        )
+
+    if event_type == "session.error":
+        message_id = props.get("messageID") or props.get("message_id")
+        error = props.get("error") or props.get("message")
+        return (
+            "error",
+            {"message_id": message_id, "error": error},
+        )
+
+    return None
+
+
+# ---------------------------------------------------------------------------
+# Helpers — opencode session id matching
+# ---------------------------------------------------------------------------
+
+
+def event_matches_session(
+    raw_event: Dict[str, Any],
+    opencode_session_id: str,
+) -> bool:
+    """Return True if `raw_event` references `opencode_session_id`.
+
+    opencode events include the session id under `sessionID` at the top
+    level OR nested under `properties.sessionID`. We check both. Events
+    without a session id (rare — typically global health/heartbeat) are
+    treated as non-matching.
+    """
+    if not isinstance(raw_event, dict):
+        return False
+    if raw_event.get("sessionID") == opencode_session_id:
+        return True
+    props = raw_event.get("properties") or {}
+    if isinstance(props, dict):
+        if props.get("sessionID") == opencode_session_id:
+            return True
+        # The session id may also live nested on a sub-object (e.g. on the
+        # `info` message for `message.updated`).
+        info = props.get("info") or props.get("message") or {}
+        if isinstance(info, dict) and info.get("sessionID") == opencode_session_id:
+            return True
+    return False
+
+
+# ---------------------------------------------------------------------------
+# Internal — timestamp parsing
+# ---------------------------------------------------------------------------
+
+
+def _parse_ts(value: Any) -> Optional[datetime]:
+    """Parse an opencode timestamp into a datetime, or None.
+
+    opencode timestamps are sometimes ISO 8601 strings, sometimes
+    ms-since-epoch ints (per its TS codebase). Be defensive about both.
+    """
+    if value is None:
+        return None
+    if isinstance(value, datetime):
+        return value
+    if isinstance(value, (int, float)):
+        # opencode timestamps are ms-since-epoch in its TS code.
+        try:
+            return datetime.utcfromtimestamp(value / 1000.0)
+        except (OverflowError, OSError, ValueError):
+            return None
+    if isinstance(value, str):
+        # Accept "2026-05-07T15:04:05.123Z" by swapping trailing Z for +00:00,
+        # which fromisoformat understands on 3.10+.
+        s = value.replace("Z", "+00:00") if value.endswith("Z") else value
+        try:
+            return datetime.fromisoformat(s)
+        except ValueError:
+            return None
+    return None