From bb2900599792494daa456e42dd251a27f47e331e Mon Sep 17 00:00:00 2001
From: kate bonner <katebonner277@gmail.com>
Date: Tue, 28 Jul 2026 19:10:45 -0400
Subject: [PATCH] fix(run): fidelity readout never rounds a near-unity F to a
 bare 1
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formatFidelity's toFixed(4) collapsed any F ≥ 0.99995 to "1" in the run
chip, ring-2 Run hero, and Run modal — hiding exactly the number that
matters. Precision now extends a digit at a time (cap 10) until the gap
from 1 (or 0) survives rounding; ordinary values keep the 4-decimal form
and only a true 1 renders bare.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
---
 packages/ui/src/amicode/problem.test.ts | 14 ++++++++++++++
 packages/ui/src/amicode/problem.ts      | 13 +++++++++++--
 2 files changed, 25 insertions(+), 2 deletions(-)

diff --git a/packages/ui/src/amicode/problem.test.ts b/packages/ui/src/amicode/problem.test.ts
index a26833e1c..ff669a05e 100644
--- a/packages/ui/src/amicode/problem.test.ts
+++ b/packages/ui/src/amicode/problem.test.ts
@@ -118,6 +118,20 @@ describe("runChipText", () => {
   test("solving f outside [0,1] renders no F readout (objective ≠ fidelity)", () => {
     expect(runChipText([{ runId: "r", status: "solving", fidelity: 79.3, iteration: 0 }])).toBe("solving…")
   })
+  test("near-unity fidelity never rounds to a bare 1 — precision extends until the gap shows", () => {
+    expect(runChipText([{ runId: "r", status: "finished", fidelity: 0.99997, iteration: 60 }])).toBe(
+      "F=0.99997 · 60 iter",
+    )
+    expect(runChipText([{ runId: "r", status: "finished", fidelity: 0.99999997, iteration: 60 }])).toBe(
+      "F=0.99999997 · 60 iter",
+    )
+    // solving mirror: a tiny live objective is a near-unity F
+    expect(runChipText([{ runId: "r", status: "solving", fidelity: 0.00003, iteration: 12 }])).toBe(
+      "solving… F=0.99997",
+    )
+    // a true 1 (and only a true 1) still renders bare
+    expect(runChipText([{ runId: "r", status: "finished", fidelity: 1, iteration: 60 }])).toBe("F=1 · 60 iter")
+  })
 })
 
 describe("railState", () => {
diff --git a/packages/ui/src/amicode/problem.ts b/packages/ui/src/amicode/problem.ts
index 7fa599346..1dc0e847e 100644
--- a/packages/ui/src/amicode/problem.ts
+++ b/packages/ui/src/amicode/problem.ts
@@ -244,8 +244,17 @@ export function mergeChips(entities: Record<string, Record<string, unknown>>, sc
 // --- run chip ----------------------------------------------------------------
 
 function formatFidelity(value: number): string {
-  // up to 4 significant decimals, trailing zeros trimmed
-  return String(Number(value.toFixed(4)))
+  // 4 decimals for ordinary values (trailing zeros trimmed) — but NEVER let
+  // rounding collapse a near-unity or near-zero fidelity into exactly "1"/"0":
+  // the gap from perfect IS the result (Kate 2026-07-28, a 0.99997 run showed
+  // "F = 1"). Precision extends one digit at a time until the gap survives,
+  // capped at 10; only a true 1 or 0 renders bare.
+  if (value === 1 || value === 0) return String(value)
+  for (let digits = 4; digits <= 10; digits++) {
+    const rounded = Number(value.toFixed(digits))
+    if (rounded !== 1 && rounded !== 0) return String(rounded)
+  }
+  return String(value)
 }
 
 export function runChipText(statuses: RunStatusView[]): string | undefined {