[verified] fix: preserve tracker precision eligibility

.scratch/proxy-stream-cancellation/PRD.md

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+# PRD: Streaming proxy cancellation delivery
+
+## Overview
+
+A tracker proxy route can be selected and registered as active, but a direct SSE upstream may not deliver its first frame to the downstream client until the upstream response completes. A dashboard cancellation request made after the upstream emitted and flushed an SSE frame can therefore arrive after the tracker has already finalized and unregistered the proxy, returning 404.
+
+## Goal
+
+Preserve immediate SSE frame delivery and keep the active-proxy record cancelable until the streaming response actually completes or is canceled.
+
+## Quality gates
+
+- Run the focused tracker streaming/cancellation tests.
+- Run full `python -m pytest -q` and record unrelated failures exactly.
+- Do not weaken billing, disconnect handling, proxy-inflight accounting, or cancel authorization.
+
+## User story
+
+### PSC-001: Cancel an active direct SSE proxy
+
+As a dashboard operator, I need a cancellation request to reach an active direct SSE proxy after its first streamed frame, so I can stop long-running inference without a race-induced 404.
+
+## Non-goals
+
+- Do not change route selection or quantization policy.
+- Do not alter relay transport behavior unless needed to share the same cancellation invariant.
+- Do not introduce client-visible buffering.