@magpie-community/middleware-param-override

New API's 参数覆盖 (a channel's param_override) as magpie gateway middleware. It sets, deletes, moves and rewrites any field of the requests agents send through magpie, whichever provider serves them. The options are New API's JSON as it is, so you can paste a param_override from New API unchanged.

Install it from magpie's Plugins › Discover, or with magpie plugin add @magpie-community/middleware-param-override. Then set its options under Plugins › Installed › Options, or with magpie plugin options param-override '<json>'.

Options

There are two forms, as in New API:

{ "temperature": 0.2, "max_tokens": 8000 }

Each key is set on the body as it is.

{ "operations": [
  { "path": "max_tokens", "mode": "set", "value": 32000,
    "conditions": [{ "path": "max_tokens", "mode": "gt", "value": 32000 }] },
  { "path": "temperature", "mode": "delete",
    "conditions": [{ "path": "model", "mode": "contains", "value": "reasoner" }] },
  { "mode": "return_error", "value": { "message": "opus is not allowed here", "status_code": 403 },
    "conditions": [{ "path": "model", "mode": "contains", "value": "opus" }] }
] }

The operations run in order. Keys set beside operations are applied first.

| Field | | | --- | --- | | path | A gjson path: a.b.0. messages.-1 counts from the end, tools.*.name matches every item, and \. is a dot inside a key. | | mode | set (keep_origin: only when missing), delete, move / copy (from, to), prepend / append (arrays joined, strings joined, objects merged; keep_origin keeps keys already there), trim_prefix, trim_suffix, ensure_prefix, ensure_suffix, trim_space, to_lower, to_upper, replace / regex_replace (from, to; Go's ${1} works), return_error, prune_objects | | value | What to set, join or trim. For return_error, a message or {message, status_code}; the agent gets the error in its own API's shape. For prune_objects, a type or {type, where, conditions, logic, recursive}. | | conditions | [{path, mode, value, invert, pass_missing_key}], where mode is full, prefix, suffix, contains, gt, gte, lt or lte. A path is looked up in the body first, then in the request: model, request_path, protocol (anthropic, chat, responses, gemini), agent, stream. | | logic | OR (New API's default) or AND. |

Some of New API's modes have nothing to act on here and are left out: the header modes (set_header, pass_headers…), sync_fields, and conditions on retries, users and groups. The middleware sees only the body.

Unlike New API, an operation that can't apply is skipped (a move from a missing path, trim_prefix on a number) and the request goes on. If the middleware itself fails, magpie sends the request as it came.

Recipes

• Cap max_tokens for a provider with a lower limit: the first example above.
• Drop a parameter a provider refuses: {"path": "tools.*.input_examples", "mode": "delete"}.
• Strip a vendor prefix from model names: {"path": "model", "mode": "trim_prefix", "value": "openai/"}.
• Keep an agent off a model: return_error with a model condition.
• Remove old thinking blocks: {"path": "messages", "mode": "prune_objects", "value": "thinking"}.

中文：New API 的「参数覆盖」，作为 magpie 网关中间件。配置是 New API 的同一份 JSON，可以原样粘贴过来。