fix(catalog): require explicit Linkup research depth

docs/context/architecture/catalog.md

@@ -317,8 +317,11 @@ Linkup's curated `web.search` and Markdown `web.extract` rows have verified rout
 Research remains a direct asynchronous `web.answer` tool. Search's `depth` and `outputType` select
 one published per-success price. The Fetch route has separate Markdown and structured catalog
 rows because supplying `schema` changes the price; both rows price `mode` and `renderJs` with
-declarative tables and enforce distinct body allowlists. Research reserves the requested
-`reasoningDepth` price, releases failed tasks, and settles successful tasks after the owned
+declarative tables and enforce distinct body allowlists. Research requires an explicit
+`reasoningDepth` so callers choose its $0.25–$2.50 price; Linkup otherwise defaults to L at $1.50.
+Its published pricing varies by depth, not mode. Research reserves the requested depth price,
+releases failed tasks under Linkup's documented no-charge-on-error policy, and settles successful
+tasks after the owned
 `GET /v1/research/{id}` poll reports completion. The polling read is free and restricted to the
 team that submitted the task on the shared key. Account-wide task listing, mixed batch Tasks,
 closed-beta Extract, and the undocumented Responses route are outside the shared-key catalog.

src/treg/catalog/linkup.yaml

@@ -156,7 +156,7 @@ endpoints:
       body:
         q: {type: string, required: true, example: "What is example.com used for?"}
         outputType: {type: string, required: true, enum: [sourcedAnswer, structured], example: sourcedAnswer}
-        reasoningDepth: {type: string, required: false, default: L, enum: [S, M, L, XL], example: S}
+        reasoningDepth: {type: string, required: true, enum: [S, M, L, XL], example: S}
         mode: {type: string, required: false, default: auto, enum: [answer, auto, investigate, research]}
         includeDomains: {type: "array[string]", required: false, maxItems: 100}
         excludeDomains: {type: "array[string]", required: false}
@@ -179,7 +179,7 @@ endpoints:
       source_url: https://docs.linkup.so/pages/documentation/platform/pricing
       checked: '2026-09-29'
       confidence: documented
-      note: "Successful Research tasks are billed by reasoning depth; failed tasks are free."
+      note: "Research price depends on reasoningDepth, not mode. Linkup documents that errors deduct no credit; treg releases a failed task's hold."
     verified: '2026-09-29'
     docs_url: https://docs.linkup.so/pages/documentation/endpoints/research/post
     example_response: examples/linkup.web.answer.json