refactor(usage): consolidate duplicate formatProviderName into shared helper

The formatProviderName function (title-casing a provider id like
'opencode-go' → 'Opencode Go') was duplicated identically across
three files:
- command-controller.ts (TUI rendering path)
- usage-cli.ts (CLI rendering path)
- usage-report.ts (ACP rendering path)

Moved the single implementation to the shared format.ts helper
(already home to formatDuration and renderAsciiBar), and updated
all three call sites to import from there.

Author: oldschoola

packages/coding-agent/CHANGELOG.md

@@ -2,6 +2,10 @@
 
 ## [Unreleased]
 
+### Changed
+
+- Consolidated duplicate `formatProviderName` function (title-casing provider ids) from three usage rendering paths into a single shared helper in `slash-commands/helpers/format.ts`
+
 ## [16.1.16] - 2026-06-23
 
 ### Breaking Changes

packages/coding-agent/src/cli/usage-cli.ts

@@ -19,6 +19,7 @@ import { formatDuration, formatNumber } from "@oh-my-pi/pi-utils";
 import chalk from "chalk";
 import { ModelRegistry } from "../config/model-registry";
 import { discoverAuthStorage } from "../sdk";
+import { formatProviderName } from "../slash-commands/helpers/format";
 
 const BAR_WIDTH = 28;
 
@@ -175,13 +176,6 @@ function aggregateStatus(limits: UsageLimit[]): LimitStatus {
 	return "unknown";
 }
 
-function formatProviderName(provider: string): string {
-	return provider
-		.split(/[-_]/g)
-		.map(part => (part ? part[0].toUpperCase() + part.slice(1) : ""))
-		.join(" ");
-}
-
 function formatUnitValue(value: number, unit: UsageUnit): string {
 	if (unit === "usd") return `$${value.toFixed(2)}`;
 	return formatNumber(value);

packages/coding-agent/src/modes/controllers/command-controller.ts

@@ -42,6 +42,7 @@ import type { CompactMode } from "../../session/compact-modes";
 import type { NewSessionOptions } from "../../session/session-entries";
 import { formatShakeSummary, type ShakeMode, type ShakeResult } from "../../session/shake-types";
 import { limitMatchesActiveAccount } from "../../slash-commands/helpers/active-oauth-account";
+import { formatProviderName } from "../../slash-commands/helpers/format";
 import { outputMeta } from "../../tools/output-meta";
 import { resolveToCwd, stripOuterDoubleQuotes } from "../../tools/path-utils";
 import { replaceTabs } from "../../tools/render-utils";
@@ -1270,13 +1271,6 @@ function truncateJobLabel(label: string, maxWidth: number): string {
 	return `${out}…`;
 }
 
-function formatProviderName(provider: string): string {
-	return provider
-		.split(/[-_]/g)
-		.map(part => (part ? part[0].toUpperCase() + part.slice(1) : ""))
-		.join(" ");
-}
-
 function formatNumber(value: number, maxFractionDigits = 1): string {
 	return new Intl.NumberFormat("en-US", { maximumFractionDigits: maxFractionDigits }).format(value);
 }

packages/coding-agent/src/slash-commands/helpers/format.ts

@@ -1,6 +1,14 @@
 import { shimmerText } from "../../modes/theme/shimmer";
 import { theme as currentTheme, type Theme } from "../../modes/theme/theme";
 
+/** Title-case a provider id for display (e.g. "opencode-go" → "Opencode Go"). */
+export function formatProviderName(provider: string): string {
+	return provider
+		.split(/[-_]/g)
+		.map(part => (part ? part[0]!.toUpperCase() + part.slice(1) : ""))
+		.join(" ");
+}
+
 /** Format a millisecond duration as a coarse-grained human label. */
 export function formatDuration(ms: number): string {
 	const seconds = Math.max(0, Math.round(ms / 1000));

packages/coding-agent/src/slash-commands/helpers/usage-report.ts

@@ -2,14 +2,7 @@ import type { UsageLimit, UsageReport } from "@oh-my-pi/pi-ai";
 import type { OAuthAccountIdentity } from "../../session/auth-storage";
 import type { SlashCommandRuntime } from "../types";
 import { reportMatchesActiveAccount } from "./active-oauth-account";
-import { formatDuration, renderAsciiBar } from "./format";
-
-function formatProviderName(provider: string): string {
-	return provider
-		.split(/[-_]/g)
-		.map(part => (part ? part[0].toUpperCase() + part.slice(1) : ""))
-		.join(" ");
-}
+import { formatDuration, formatProviderName, renderAsciiBar } from "./format";
 
 function formatUsageAmount(limit: UsageLimit): string {
 	const amount = limit.amount;