diff --git a/packages/client/src/generated-effect/client.ts b/packages/client/src/generated-effect/client.ts
index 024c9782806c..c042eb577dd5 100644
--- a/packages/client/src/generated-effect/client.ts
+++ b/packages/client/src/generated-effect/client.ts
@@ -207,6 +207,12 @@ const Endpoint3_16 = (raw: RawClient["server.session"]) => (input: Endpoint3_16I
     Effect.map((value) => value.data),
   )
 
+const Endpoint3_17 = (raw: RawClient["server.session"]) => () =>
+  raw["session.cost"]({}).pipe(
+    Effect.mapError(mapClientError),
+    Effect.map((value) => value.data),
+  )
+
 const adaptGroup3 = (raw: RawClient["server.session"]) => ({
   list: Endpoint3_0(raw),
   create: Endpoint3_1(raw),
@@ -225,6 +231,7 @@ const adaptGroup3 = (raw: RawClient["server.session"]) => ({
   events: Endpoint3_14(raw),
   interrupt: Endpoint3_15(raw),
   message: Endpoint3_16(raw),
+  cost: Endpoint3_17(raw),
 })
 
 type Endpoint4_0Request = Parameters<RawClient["server.message"]["session.messages"]>[0]
diff --git a/packages/client/src/generated/client.ts b/packages/client/src/generated/client.ts
index 27ec3d81ba2c..f527e77fb6f6 100644
--- a/packages/client/src/generated/client.ts
+++ b/packages/client/src/generated/client.ts
@@ -37,6 +37,7 @@ import type {
   SessionsInterruptOutput,
   SessionsMessageInput,
   SessionsMessageOutput,
+  SessionsCostOutput,
   MessagesListInput,
   MessagesListOutput,
   ModelsListInput,
@@ -492,6 +493,11 @@ export function make(options: ClientOptions) {
           },
           requestOptions,
         ).then((value) => value.data),
+      cost: (requestOptions?: RequestOptions) =>
+        request<{ readonly data: SessionsCostOutput }>(
+          { method: "GET", path: `/api/session/cost`, successStatus: 200, declaredStatuses: [401, 400], empty: false },
+          requestOptions,
+        ).then((value) => value.data),
     },
     messages: {
       list: (input: MessagesListInput, requestOptions?: RequestOptions) =>
diff --git a/packages/client/src/generated/types.ts b/packages/client/src/generated/types.ts
index 3b3188c8742a..a70144608c44 100644
--- a/packages/client/src/generated/types.ts
+++ b/packages/client/src/generated/types.ts
@@ -1753,6 +1753,8 @@ export type SessionsMessageOutput = {
       }
 }["data"]
 
+export type SessionsCostOutput = { readonly data: number }["data"]
+
 export type MessagesListInput = {
   readonly sessionID: { readonly sessionID: string }["sessionID"]
   readonly limit?: {
diff --git a/packages/core/src/session.ts b/packages/core/src/session.ts
index 2dabfb2d6fba..9450b31ba265 100644
--- a/packages/core/src/session.ts
+++ b/packages/core/src/session.ts
@@ -3,7 +3,7 @@ export * from "./session/schema"
 
 import { DateTime, Effect, Layer, Schema, Context, Stream } from "effect"
 import { ListAnchor } from "@opencode-ai/schema/session"
-import { and, asc, desc, eq, gt, like, lt, or, type SQL } from "drizzle-orm"
+import { and, asc, desc, eq, gt, gte, like, lt, or, type SQL } from "drizzle-orm"
 import { ProjectV2 } from "./project"
 import { WorkspaceV2 } from "./workspace"
 import { ModelV2 } from "./model"
@@ -101,6 +101,10 @@ export class OperationUnavailableError extends Schema.TaggedErrorClass<Operation
 
 export { ContextSnapshotDecodeError, MessageDecodeError } from "./session/error"
 
+export function sumSessionCosts(sessions: readonly { readonly cost?: number }[]) {
+  return sessions.reduce((total, session) => total + (session.cost ?? 0), 0)
+}
+
 export class PromptConflictError extends Schema.TaggedErrorClass<PromptConflictError>()("Session.PromptConflictError", {
   sessionID: SessionSchema.ID,
   messageID: SessionMessage.ID,
@@ -112,6 +116,7 @@ export type Error = NotFoundError | MessageDecodeError | OperationUnavailableErr
 
 export interface Interface {
   readonly list: (input?: ListInput) => Effect.Effect<SessionSchema.Info[]>
+  readonly todayCost: Effect.Effect<number>
   readonly create: (input: CreateInput) => Effect.Effect<SessionSchema.Info>
   readonly get: (sessionID: SessionSchema.ID) => Effect.Effect<SessionSchema.Info, NotFoundError>
   readonly messages: (input: {
@@ -205,6 +210,17 @@ const layer = Layer.effect(
       )
 
     const result = Service.of({
+      todayCost: Effect.gen(function* () {
+        const start = new Date()
+        start.setHours(0, 0, 0, 0)
+        const rows = yield* db
+          .select({ cost: SessionTable.cost })
+          .from(SessionTable)
+          .where(gte(SessionTable.time_updated, start.getTime()))
+          .all()
+          .pipe(Effect.orDie)
+        return sumSessionCosts(rows)
+      }),
       create: Effect.fn("V2Session.create")(function* (input) {
         const sessionID = input.id ?? SessionSchema.ID.create()
         const recorded = yield* store.get(sessionID)
diff --git a/packages/core/test/session-cost.test.ts b/packages/core/test/session-cost.test.ts
new file mode 100644
index 000000000000..b329a2984230
--- /dev/null
+++ b/packages/core/test/session-cost.test.ts
@@ -0,0 +1,6 @@
+import { expect, test } from "bun:test"
+import { sumSessionCosts } from "@opencode-ai/core/session"
+
+test("sums session costs and treats missing costs as zero", () => {
+  expect(sumSessionCosts([{ cost: 0.05 }, {}, { cost: 10.29 }])).toBeCloseTo(10.34)
+})
diff --git a/packages/opencode/src/cli/cmd/stats.ts b/packages/opencode/src/cli/cmd/stats.ts
index 22dee14772cd..39601f0a6464 100644
--- a/packages/opencode/src/cli/cmd/stats.ts
+++ b/packages/opencode/src/cli/cmd/stats.ts
@@ -6,6 +6,7 @@ import { Database } from "@opencode-ai/core/database/database"
 import { SessionTable } from "@opencode-ai/core/session/sql"
 import { Project } from "@/project/project"
 import { InstanceRef } from "@/effect/instance-ref"
+import { sumSessionCosts } from "@opencode-ai/core/session"
 
 interface SessionStats {
   totalSessions: number
@@ -124,7 +125,7 @@ const aggregateSessionStats = Effect.fn("Cli.stats.aggregate")(function* (
   const stats: SessionStats = {
     totalSessions: filteredSessions.length,
     totalMessages: 0,
-    totalCost: 0,
+    totalCost: sumSessionCosts(filteredSessions),
     totalTokens: {
       input: 0,
       output: 0,
@@ -168,7 +169,6 @@ const aggregateSessionStats = Effect.fn("Cli.stats.aggregate")(function* (
           .messages({ sessionID: session.id })
           .pipe(Effect.catchIf(NotFoundError.isInstance, () => Effect.succeed([])))
 
-        const sessionCost = session.cost ?? 0
         const sessionTokens = session.tokens ?? { input: 0, output: 0, reasoning: 0, cache: { read: 0, write: 0 } }
         let sessionToolUsage: Record<string, number> = {}
         let sessionModelUsage: Record<
@@ -211,7 +211,6 @@ const aggregateSessionStats = Effect.fn("Cli.stats.aggregate")(function* (
 
         return {
           messageCount: messages.length,
-          sessionCost,
           sessionTokens,
           sessionTotalTokens:
             sessionTokens.input +
@@ -234,7 +233,6 @@ const aggregateSessionStats = Effect.fn("Cli.stats.aggregate")(function* (
     sessionTotalTokens.push(result.sessionTotalTokens)
 
     stats.totalMessages += result.messageCount
-    stats.totalCost += result.sessionCost
     stats.totalTokens.input += result.sessionTokens.input
     stats.totalTokens.output += result.sessionTokens.output
     stats.totalTokens.reasoning += result.sessionTokens.reasoning
diff --git a/packages/plugin/src/tui.ts b/packages/plugin/src/tui.ts
index 67812169475b..697f2ef64d49 100644
--- a/packages/plugin/src/tui.ts
+++ b/packages/plugin/src/tui.ts
@@ -419,6 +419,7 @@ type TuiAttentionConfigView = {
 type TuiConfigView = Pick<PluginConfig, "$schema" | "theme" | "plugin"> &
   NonNullable<PluginConfig["tui"]> & {
     leader_timeout: number
+    show_today_cost: boolean
     attention: TuiAttentionConfigView
     plugin_enabled?: Record<string, boolean>
     keybinds: TuiBindingLookupView
diff --git a/packages/protocol/src/groups/session.ts b/packages/protocol/src/groups/session.ts
index 8ce85ef79686..478eaf40e37c 100644
--- a/packages/protocol/src/groups/session.ts
+++ b/packages/protocol/src/groups/session.ts
@@ -371,6 +371,17 @@ export const makeSessionGroup = <I extends HttpApiMiddleware.AnyId, S>(sessionLo
           }),
         ),
     )
+    .add(
+      HttpApiEndpoint.get("session.cost", "/api/session/cost", {
+        success: Schema.Struct({ data: Schema.Finite }),
+      }).annotateMerge(
+        OpenApi.annotations({
+          identifier: "v2.session.cost",
+          summary: "Get today's session cost",
+          description: "Get the total cost of sessions updated since local midnight.",
+        }),
+      ),
+    )
     .annotateMerge(
       OpenApi.annotations({
         title: "sessions",
diff --git a/packages/sdk/js/src/v2/gen/sdk.gen.ts b/packages/sdk/js/src/v2/gen/sdk.gen.ts
index 9ed0084aac84..78c231374856 100644
--- a/packages/sdk/js/src/v2/gen/sdk.gen.ts
+++ b/packages/sdk/js/src/v2/gen/sdk.gen.ts
@@ -339,6 +339,8 @@ import type {
   V2SessionCompactResponses,
   V2SessionContextErrors,
   V2SessionContextResponses,
+  V2SessionCostErrors,
+  V2SessionCostResponses,
   V2SessionCreateErrors,
   V2SessionCreateResponses,
   V2SessionEventsErrors,
@@ -5466,6 +5468,18 @@ export class Session3 extends HeyApiClient {
     })
   }
 
+  /**
+   * Get today's session cost
+   *
+   * Get the total cost of sessions updated since local midnight.
+   */
+  public cost<ThrowOnError extends boolean = false>(options?: Options<never, ThrowOnError>) {
+    return (options?.client ?? this.client).get<V2SessionCostResponses, V2SessionCostErrors, ThrowOnError>({
+      url: "/api/session/cost",
+      ...options,
+    })
+  }
+
   /**
    * Create session
    *
diff --git a/packages/sdk/js/src/v2/gen/types.gen.ts b/packages/sdk/js/src/v2/gen/types.gen.ts
index 90c91e9158cc..efa74d3aa307 100644
--- a/packages/sdk/js/src/v2/gen/types.gen.ts
+++ b/packages/sdk/js/src/v2/gen/types.gen.ts
@@ -11370,6 +11370,28 @@ export type V2SessionListResponses = {
 
 export type V2SessionListResponse = V2SessionListResponses[keyof V2SessionListResponses]
 
+export type V2SessionCostData = {
+  body?: never
+  path?: never
+  query?: never
+  url: "/api/session/cost"
+}
+
+export type V2SessionCostErrors = {
+  400: InvalidRequestError
+  401: UnauthorizedError
+}
+
+export type V2SessionCostError = V2SessionCostErrors[keyof V2SessionCostErrors]
+
+export type V2SessionCostResponses = {
+  200: {
+    data: number
+  }
+}
+
+export type V2SessionCostResponse = V2SessionCostResponses[keyof V2SessionCostResponses]
+
 export type V2SessionCreateData = {
   body: {
     id?: string
diff --git a/packages/server/src/handlers/session.ts b/packages/server/src/handlers/session.ts
index 5b7d354b04fc..222a56cacd47 100644
--- a/packages/server/src/handlers/session.ts
+++ b/packages/server/src/handlers/session.ts
@@ -21,6 +21,12 @@ export const SessionHandler = HttpApiBuilder.group(Api, "server.session", (handl
     const session = yield* SessionV2.Service
 
     return handlers
+      .handle(
+        "session.cost",
+        Effect.fn(function* () {
+          return { data: yield* session.todayCost }
+        }),
+      )
       .handle(
         "session.list",
         Effect.fn(function* (ctx) {
diff --git a/packages/tui/src/config/index.tsx b/packages/tui/src/config/index.tsx
index df9239763a68..e5dfc208e6b9 100644
--- a/packages/tui/src/config/index.tsx
+++ b/packages/tui/src/config/index.tsx
@@ -63,10 +63,14 @@ export const Info = Schema.Struct({
   scroll_acceleration: Schema.optional(ScrollAcceleration),
   diff_style: Schema.optional(DiffStyle),
   mouse: Schema.optional(Schema.Boolean).annotate({ description: "Enable or disable mouse capture (default: true)" }),
+  show_today_cost: Schema.optional(Schema.Boolean).annotate({
+    description: "Show today's session cost in the sidebar Context section (default: false)",
+  }),
 })
 export type Info = Schema.Schema.Type<typeof Info>
 
 export type Resolved = Omit<Info, "attention" | "keybinds" | "leader_timeout" | "mouse"> & {
+  show_today_cost: boolean
   attention: {
     enabled: boolean
     notifications: boolean
@@ -113,6 +117,7 @@ export function resolve(input: Info, options: ResolveOptions): Resolved {
     }),
     leader_timeout: input.leader_timeout ?? LeaderTimeoutDefault,
     mouse: input.mouse ?? true,
+    show_today_cost: input.show_today_cost ?? false,
   }
 }
 
diff --git a/packages/tui/src/feature-plugins/sidebar/context.tsx b/packages/tui/src/feature-plugins/sidebar/context.tsx
index f1c99d9679ce..b605715b431c 100644
--- a/packages/tui/src/feature-plugins/sidebar/context.tsx
+++ b/packages/tui/src/feature-plugins/sidebar/context.tsx
@@ -1,7 +1,7 @@
 import type { AssistantMessage } from "@opencode-ai/sdk/v2"
 import type { TuiPlugin, TuiPluginApi } from "@opencode-ai/plugin/tui"
 import type { BuiltinTuiPlugin } from "../builtins"
-import { createMemo } from "solid-js"
+import { createEffect, createMemo, createSignal, onCleanup, onMount, Show } from "solid-js"
 
 const id = "internal:sidebar-context"
 
@@ -14,7 +14,29 @@ function View(props: { api: TuiPluginApi; session_id: string }) {
   const theme = () => props.api.theme.current
   const msg = createMemo(() => props.api.state.session.messages(props.session_id))
   const session = createMemo(() => props.api.state.session.get(props.session_id))
-  const cost = createMemo(() => session()?.cost ?? 0)
+  const [sessionCost, setSessionCost] = createSignal<number>()
+  const cost = createMemo(() => sessionCost() ?? session()?.cost ?? 0)
+  const [todayCost, setTodayCost] = createSignal<number>()
+
+  const refreshCosts = async () => {
+    const [sessionResult, todayResult] = await Promise.all([
+      props.api.client.v2.session.get({ sessionID: props.session_id }).catch(() => undefined),
+      props.api.tuiConfig.show_today_cost ? props.api.client.v2.session.cost().catch(() => undefined) : undefined,
+    ])
+    const currentSessionCost = sessionResult?.data?.data.cost
+    if (currentSessionCost !== undefined) setSessionCost(currentSessionCost)
+    if (todayResult?.data?.data !== undefined) setTodayCost(todayResult.data.data)
+  }
+
+  createEffect(() => {
+    session()
+    void refreshCosts()
+  })
+
+  onMount(() => {
+    const interval = setInterval(refreshCosts, 30_000)
+    onCleanup(() => clearInterval(interval))
+  })
 
   const state = createMemo(() => {
     const last = msg().findLast((item): item is AssistantMessage => item.role === "assistant" && item.tokens.output > 0)
@@ -42,6 +64,9 @@ function View(props: { api: TuiPluginApi; session_id: string }) {
       <text fg={theme().textMuted}>{state().tokens.toLocaleString()} tokens</text>
       <text fg={theme().textMuted}>{state().percent ?? 0}% used</text>
       <text fg={theme().textMuted}>{money.format(cost())} spent</text>
+      <Show when={props.api.tuiConfig.show_today_cost && todayCost() !== undefined}>
+        <text fg={theme().textMuted}>{money.format(todayCost()!)} today</text>
+      </Show>
     </box>
   )
 }