diff --git a/AGENTS.md b/AGENTS.md
index 7b45dafa..e7f02fef 100644
--- a/AGENTS.md
+++ b/AGENTS.md
@@ -80,6 +80,7 @@ npm start build-cmd     # tsc --project etc/tsc.json (emits into dst/)
 npm start build-plugin  # copy ../plugin and ../.claude-plugin into the package
 npm start build-watch   # nodemon rebuild on src/**/*.ts
 npm start lint-watch    # nodemon relint on src/**/*.ts
+npm start prices-update # refresh checked-in LiteLLM price snapshot (needs network)
 
 cd pages
 npm start lint          # astro check + eslint over src/**/*.{ts,astro}
diff --git a/docs/usage-tool.md b/docs/usage-tool.md
index 503a9f80..ffdb63e8 100644
--- a/docs/usage-tool.md
+++ b/docs/usage-tool.md
@@ -177,7 +177,7 @@ background service as an *Anthropic Claude Code CLI* MCP server:
 The following top-level command exists for rendering the *Anthropic Claude Code CLI*
 or *GitHub Copilot CLI* statusline:
 
-- `ase statusline` \[`-t`|`--tool` `claude`|`copilot`\] \[`-w`|`--width` *n*\] \[`-m`|`--margin` *n*\] \[`-p`|`--padding` *n*\] \[`--no-icons`\] \[`--no-labels`\] \[*line* \[...\]\]:
+- `ase statusline` \[`-t`|`--tool` `claude`|`copilot`\] \[`-w`|`--width` *n*\] \[`-m`|`--margin` *n*\] \[`-p`|`--padding` *n*\] \[`--no-icons`\] \[`--no-labels`\] \[`--month-cost-ttl` *n*\] \[*line* \[...\]\]:
   Render the *Anthropic Claude Code CLI* or *GitHub Copilot CLI* statusline from a
   JSON payload read on standard input. Intended to be configured as
   the `statusLine` command in *Anthropic Claude Code CLI* settings (or the
@@ -216,7 +216,9 @@ or *GitHub Copilot CLI* statusline:
   e.g. `4hr 27m`), `%W` (7-day rate-limit window used percentage),
   `%Q` (7-day window time-until-reset), `%H` (session wall-clock
   duration, e.g. `92hr 40m`), `%X` (session cost in USD, e.g.
-  `$54.44`), `%b` (git branch, or `no git`), `%g` (git changed lines,
+  `$54.44`), `%Y` (cumulative cost in USD across *all* sessions of
+  *all* supported agent tools within the current calendar month, e.g.
+  `$1102.11`), `%b` (git branch, or `no git`), `%g` (git changed lines,
   e.g. `+42/-7`), `%G` (git untracked file count), `%d` (full
   current working directory path), `%M` (memory used/total, e.g.
   `33.2G/64.0G`), `%V` (combined *Anthropic Claude Code CLI* and *ASE*
@@ -259,7 +261,32 @@ or *GitHub Copilot CLI* statusline:
     - \[`--no-labels`\]:
       disable the textual label (e.g. `user:`, `project:`, `model:`)
       in front of the bold value of each placeholder rendering.
-  When run inside a *tmux* pane, the resolved task id is also
+    - \[`--month-cost-ttl` *n*\]:
+      seconds the `%Y` current-month total cost is cached before a
+      non-blocking background refresh is triggered (default: `300`).
+  The `%Y` placeholder reports the cumulative cost (in USD) of *all*
+  agent sessions within the current calendar month, unlike `%X` which
+  only reflects the current session. The month boundary is a *UTC* one,
+  matching the day on which the model vendors bill and reset their
+  usage windows. The figure is computed locally, without any network
+  access, from the session logs of every supported agent tool:
+  *Anthropic Claude Code CLI* (`~/.claude/projects/**/*.jsonl`, honoring
+  `CLAUDE_CONFIG_DIR`), *OpenAI Codex CLI*
+  (`~/.codex/{sessions,archived_sessions}/**/rollout-*.jsonl`, honoring
+  `CODEX_HOME`), and *GitHub Copilot CLI*
+  (`~/.copilot/session-state/**/*.jsonl`, honoring
+  `COPILOT_CONFIG_DIR`). Per logged model call, the token counts
+  (uncached input, output including reasoning, cache-read, and
+  5-minute / 1-hour cache-write) are multiplied by the per-model prices
+  of the *LiteLLM* price snapshot bundled with *ASE* (see `npm start
+  prices-update`); a call logged more than once - while its response
+  streams, or after a session was resumed or forked - is billed only
+  once, and a model absent from the snapshot contributes nothing.
+  To keep rendering fast, the result is cached in the temporary
+  directory and recomputed at most once per *--month-cost-ttl* window
+  by a detached background process, so a render never blocks on the
+  log scan; missing or empty logs simply suppress the
+  placeholder. When run inside a *tmux* pane, the resolved task id is also
   published as the per-pane user option `@ase_task_id`, so external
   tools (like the *claudeX* sister project) can pick it up via
   `#{@ase_task_id}`.
diff --git a/tool/etc/litellm-prices.mjs b/tool/etc/litellm-prices.mjs
new file mode 100644
index 00000000..76641b82
--- /dev/null
+++ b/tool/etc/litellm-prices.mjs
@@ -0,0 +1,94 @@
+/*
+**  Agentic Software Engineering (ASE)
+**  Copyright (c) 2025-2026 Dr. Ralf S. Engelschall <rse@engelschall.com>
+**  Licensed under Apache 2.0 <https://spdx.org/licenses/Apache-2.0>
+*/
+
+/*  Regenerate the per-model token price snapshot in "src/ase-statusline-prices.ts"
+    from LiteLLM's canonical price database. Run via "npm start prices-update".
+    The snapshot is checked in on purpose, so that both the build and the
+    statusline rendering stay entirely offline.  */
+
+import fs   from "node:fs"
+import path from "node:path"
+import url  from "node:url"
+
+/*  canonical upstream price database (the same source ccusage and codeburn use)  */
+const SOURCE = "https://raw.githubusercontent.com/BerriAI/litellm/main/model_prices_and_context_window.json"
+
+/*  LiteLLM providers whose models can show up in the session logs of the
+    supported agent tools (Anthropic Claude Code, OpenAI Codex CLI, and
+    GitHub Copilot CLI, which brokers models of several vendors)  */
+const PROVIDERS = new Set([ "anthropic", "openai", "gemini", "xai", "deepseek", "mistral" ])
+
+/*  LiteLLM modes that bill input/output tokens of a conversation  */
+const MODES = new Set([ "chat", "responses" ])
+
+const main = async () => {
+    const res = await fetch(SOURCE)
+    if (!res.ok)
+        throw new Error(`fetching ${SOURCE} failed: ${res.status} ${res.statusText}`)
+    const db = await res.json()
+
+    /*  reduce the database to the token prices of the relevant models, keying
+        them by their bare model id: LiteLLM prefixes most non-OpenAI models
+        with their provider ("gemini/gemini-2.5-pro"), while the agent tools
+        log the bare id. An already bare entry always wins over a prefixed
+        one, so that the canonical price is never shadowed.  */
+    const prices = new Map()
+    for (const [ id, spec ] of Object.entries(db)) {
+        if (typeof spec !== "object" || spec === null)
+            continue
+        if (!PROVIDERS.has(spec.litellm_provider) || !MODES.has(spec.mode))
+            continue
+        const input  = spec.input_cost_per_token
+        const output = spec.output_cost_per_token
+        if (typeof input !== "number" || typeof output !== "number")
+            continue
+
+        /*  cache-read defaults to the regular input price (a model without
+            prompt caching never reports cached tokens anyway), while a
+            missing cache-write price means writing is not billed at all  */
+        const cacheRead   = typeof spec.cache_read_input_token_cost              === "number" ?
+            spec.cache_read_input_token_cost : input
+        const cacheWrite  = typeof spec.cache_creation_input_token_cost          === "number" ?
+            spec.cache_creation_input_token_cost : 0
+        const cacheWrite1 = typeof spec.cache_creation_input_token_cost_above_1hr === "number" ?
+            spec.cache_creation_input_token_cost_above_1hr : cacheWrite
+
+        const bare   = id.includes("/") ? id.slice(id.indexOf("/") + 1) : id
+        const prefix = id.includes("/")
+        if (prices.has(bare) && prefix)
+            continue
+        prices.set(bare, [ input, output, cacheRead, cacheWrite, cacheWrite1 ])
+    }
+
+    const ids   = [ ...prices.keys() ].sort()
+    const lines = ids.map((id) => `    ${JSON.stringify(id)}: ${
+        JSON.stringify(prices.get(id)).replace(/,/g, ", ").replace(/^\[/, "[ ").replace(/\]$/, " ]")}`)
+
+    const out = `/*
+**  Agentic Software Engineering (ASE)
+**  Copyright (c) 2025-2026 Dr. Ralf S. Engelschall <rse@engelschall.com>
+**  Licensed under GPL 3.0 <https://spdx.org/licenses/GPL-3.0-only>
+*/
+
+/*  GENERATED FILE -- do NOT edit manually.
+    Regenerate with "npm start prices-update" (see etc/litellm-prices.mjs).
+    Source: ${SOURCE}  */
+
+/*  per-model token prices in USD per single token, as the tuple
+    [ input, output, cache-read, cache-write (5m), cache-write (1h) ]  */
+export type Price = readonly [ number, number, number, number, number ]
+
+export const prices: Readonly<Record<string, Price>> = {
+${lines.join(",\n")}
+}
+`
+    const dir  = path.dirname(url.fileURLToPath(import.meta.url))
+    const file = path.resolve(dir, "..", "src", "ase-statusline-prices.ts")
+    fs.writeFileSync(file, out, "utf8")
+    process.stdout.write(`ase: prices-update: wrote ${ids.length} model prices to ${file}\n`)
+}
+
+await main()
diff --git a/tool/etc/stx.conf b/tool/etc/stx.conf
index 04d934dd..c8240e5e 100644
--- a/tool/etc/stx.conf
+++ b/tool/etc/stx.conf
@@ -16,6 +16,10 @@ lint-watch
 build-watch
     nodemon --exec "npm start build" --watch src --ext ts
 
+#   [tool] refresh the checked-in per-model token price snapshot (requires network)
+prices-update
+    node etc/litellm-prices.mjs
+
 #   [tool] build entire project
 build : lint build-cmd build-plugin
 
diff --git a/tool/src/ase-statusline-cost.ts b/tool/src/ase-statusline-cost.ts
new file mode 100644
index 00000000..503ff792
--- /dev/null
+++ b/tool/src/ase-statusline-cost.ts
@@ -0,0 +1,385 @@
+/*
+**  Agentic Software Engineering (ASE)
+**  Copyright (c) 2025-2026 Dr. Ralf S. Engelschall <rse@engelschall.com>
+**  Licensed under GPL 3.0 <https://spdx.org/licenses/GPL-3.0-only>
+*/
+
+import fs          from "node:fs"
+import os          from "node:os"
+import path        from "node:path"
+import { spawn }   from "node:child_process"
+
+import { prices }  from "./ase-statusline-prices.js"
+import type { Price } from "./ase-statusline-prices.js"
+
+/*  on-disk cache shape for the cumulative current-month cost  */
+export interface MonthCostCache {
+    version:    number   /*  computation scheme, to invalidate results of an older ASE  */
+    month:      string   /*  "YYYY-MM" in UTC  */
+    costUsd:    number   /*  cumulative cost across all sessions of all agent tools  */
+    computedAt: number   /*  epoch milliseconds of the last computation  */
+}
+
+/*  current computation scheme: bump whenever the scanning, pricing, or
+    month-bucketing semantics change, so that a cache written by an older
+    ASE is discarded instead of being rendered as if it were current  */
+const SCHEME = 2
+
+/*  normalized token usage of a single billed model call  */
+interface Usage {
+    input:        number   /*  uncached input tokens  */
+    output:       number   /*  generated tokens, including reasoning tokens  */
+    cacheRead:    number   /*  prompt-cache read tokens  */
+    cacheWrite5m: number   /*  prompt-cache write tokens with the 5-minute TTL  */
+    cacheWrite1h: number   /*  prompt-cache write tokens with the 1-hour TTL  */
+}
+
+/*  a single billed model call, as reconstructed from an agent tool session log  */
+interface Call {
+    key:   string   /*  stable identity, so that a call logged more than once is billed once  */
+    model: string
+    usage: Usage
+}
+
+const noUsage = (): Usage => ({ input: 0, output: 0, cacheRead: 0, cacheWrite5m: 0, cacheWrite1h: 0 })
+
+/*  resolve the token prices of a model id. The agent tools log ids in
+    varying shapes, so the lookup widens step by step: the bare id, the id
+    with dots normalized to dashes (Copilot renders "claude-sonnet-4.5"),
+    the id without its vendor prefix ("anthropic/claude-opus-5"), and
+    finally the longest matching id prefix, which maps dated snapshots
+    like "claude-opus-5-20260401" onto their base entry. A model that
+    remains unknown contributes nothing, since it cannot be priced.  */
+const resolved = new Map<string, Price | null>()
+const resolvePrice = (model: string): Price | null => {
+    const memo = resolved.get(model)
+    if (memo !== undefined)
+        return memo
+    const price = resolvePriceUncached(model)
+    resolved.set(model, price)
+    return price
+}
+const resolvePriceUncached = (model: string): Price | null => {
+    const candidates = [ model, model.replace(/\./g, "-") ]
+    if (model.includes("/"))
+        candidates.push(model.slice(model.indexOf("/") + 1))
+    for (const candidate of candidates)
+        if (prices[candidate] !== undefined)
+            return prices[candidate]!
+    let best: string | null = null
+    for (const candidate of candidates)
+        for (const id of Object.keys(prices))
+            if (candidate.startsWith(id) && (best === null || id.length > best.length))
+                best = id
+    return best !== null ? prices[best]! : null
+}
+
+/*  price a single call, returning 0 for a model without known prices  */
+const costOf = (call: Call): number => {
+    const price = resolvePrice(call.model)
+    if (price === null)
+        return 0
+    const [ input, output, cacheRead, cacheWrite5m, cacheWrite1h ] = price
+    return call.usage.input        * input +
+           call.usage.output       * output +
+           call.usage.cacheRead    * cacheRead +
+           call.usage.cacheWrite5m * cacheWrite5m +
+           call.usage.cacheWrite1h * cacheWrite1h
+}
+
+/*  derive the "YYYY-MM" key of a date in UTC: the agent vendors bill and
+    reset their usage windows on UTC days, so a local-time month boundary
+    would attribute the calls of a late evening to the wrong month  */
+const monthKeyOf = (d: Date): string => {
+    const y = d.getUTCFullYear()
+    const m = d.getUTCMonth() + 1
+    return `${y}-${m < 10 ? "0" : ""}${m}`
+}
+
+/*  first millisecond of the UTC month a date falls into  */
+const startOfMonth = (d: Date): number =>
+    Date.UTC(d.getUTCFullYear(), d.getUTCMonth(), 1)
+
+/*  parse a timestamp of any shape the session logs use (ISO 8601 string or
+    epoch seconds/milliseconds), returning null when it is unusable  */
+const parseTime = (raw: unknown): Date | null => {
+    if (typeof raw === "number") {
+        const d = new Date(raw < 1e12 ? raw * 1000 : raw)
+        return Number.isNaN(d.getTime()) ? null : d
+    }
+    if (typeof raw === "string" && raw !== "") {
+        const d = new Date(raw)
+        return Number.isNaN(d.getTime()) ? null : d
+    }
+    return null
+}
+
+/*  resolve a configuration root directory, honoring an environment override  */
+const rootDir = (envVar: string, fallback: string): string => {
+    const env = process.env[envVar]
+    if (env !== undefined && env.trim() !== "")
+        return env.trim()
+    return path.join(os.homedir(), fallback)
+}
+
+/*  recursively yield every file below a directory whose name passes a filter  */
+function * filesBelow (dir: string, accept: (name: string) => boolean): Generator<string> {
+    let entries: fs.Dirent[]
+    try {
+        entries = fs.readdirSync(dir, { withFileTypes: true })
+    }
+    catch (_e) {
+        return
+    }
+    for (const ent of entries) {
+        const p = path.join(dir, ent.name)
+        if (ent.isDirectory())
+            yield * filesBelow(p, accept)
+        else if (ent.isFile() && accept(ent.name))
+            yield p
+    }
+}
+
+/*  read a session log as parsed JSONL records, skipping whole files that were
+    not touched within the month (they cannot hold a current-month call, which
+    keeps the scan off the entire archive) and tolerating malformed lines  */
+function * records (file: string, since: number): Generator<{ obj: any, line: number }> {
+    try {
+        if (fs.statSync(file).mtimeMs < since)
+            return
+    }
+    catch (_e) {
+        return
+    }
+    let lines: string[]
+    try {
+        lines = fs.readFileSync(file, "utf8").split("\n")
+    }
+    catch (_e) {
+        return
+    }
+    for (let i = 0; i < lines.length; i++) {
+        if (lines[i] === "")
+            continue
+        try {
+            yield { obj: JSON.parse(lines[i]!), line: i }
+        }
+        catch (_e) {
+            /*  a truncated trailing line of a live session is expected  */
+        }
+    }
+}
+
+/*  scan the session logs of Anthropic Claude Code. Every assistant record
+    carries the usage of exactly one API call, but the same call is written
+    repeatedly while its response streams and again when a session is resumed
+    or forked, so the message id keys the de-duplication.  */
+function * scanClaude (month: string, since: number): Generator<Call> {
+    const root = path.join(rootDir("CLAUDE_CONFIG_DIR", ".claude"), "projects")
+    for (const file of filesBelow(root, (n) => n.endsWith(".jsonl"))) {
+        for (const { obj, line } of records(file, since)) {
+            const usage = obj?.message?.usage
+            if (usage === undefined || usage === null)
+                continue
+            const at = parseTime(obj?.timestamp)
+            if (at === null || monthKeyOf(at) !== month)
+                continue
+            const u = noUsage()
+            u.input     = usage.input_tokens            ?? 0
+            u.output    = usage.output_tokens           ?? 0
+            u.cacheRead = usage.cache_read_input_tokens ?? 0
+            const c5 = usage.cache_creation?.ephemeral_5m_input_tokens
+            const c1 = usage.cache_creation?.ephemeral_1h_input_tokens
+            if (c5 !== undefined || c1 !== undefined) {
+                u.cacheWrite5m = c5 ?? 0
+                u.cacheWrite1h = c1 ?? 0
+            }
+            else
+                u.cacheWrite5m = usage.cache_creation_input_tokens ?? 0
+            const id = typeof obj?.message?.id === "string" ? obj.message.id : ""
+            yield {
+                key:   id !== "" ? `claude:${id}` : `claude:${file}:${line}`,
+                model: typeof obj?.message?.model === "string" ? obj.message.model : "",
+                usage: u
+            }
+        }
+    }
+}
+
+/*  scan the rollout logs of the OpenAI Codex CLI. Codex reports the usage of
+    a call in a dedicated "token_count" event whose "last_token_usage" holds
+    the delta of that very call, so the events are summed as they come and
+    keyed positionally. The model is carried by the session and turn headers
+    rather than by the usage event itself.  */
+function * scanCodex (month: string, since: number): Generator<Call> {
+    const root = rootDir("CODEX_HOME", ".codex")
+    for (const dir of [ path.join(root, "sessions"), path.join(root, "archived_sessions") ]) {
+        for (const file of filesBelow(dir, (n) => n.startsWith("rollout-") && n.endsWith(".jsonl"))) {
+            let model = "gpt-5"
+            for (const { obj, line } of records(file, since)) {
+                const payload = obj?.payload
+                const named   = payload?.model ?? payload?.info?.model ?? payload?.info?.model_name
+                if (typeof named === "string" && named !== "")
+                    model = named
+                if (obj?.type !== "event_msg" || payload?.type !== "token_count")
+                    continue
+                const usage = payload?.info?.last_token_usage
+                if (usage === undefined || usage === null)
+                    continue
+                const at = parseTime(obj?.timestamp)
+                if (at === null || monthKeyOf(at) !== month)
+                    continue
+
+                /*  Codex counts the cached tokens within its input total,
+                    so the uncached remainder has to be recovered  */
+                const cached = usage.cached_input_tokens ?? 0
+                const u = noUsage()
+                u.input     = Math.max(0, (usage.input_tokens ?? 0) - cached)
+                u.output    = (usage.output_tokens ?? 0) + (usage.reasoning_output_tokens ?? 0)
+                u.cacheRead = cached
+                yield { key: `codex:${file}:${line}`, model, usage: u }
+            }
+        }
+    }
+}
+
+/*  scan the session state of the GitHub Copilot CLI. Copilot aggregates the
+    usage per model over the whole session, so a single record yields one
+    entry per involved model, and its input total covers the cached tokens as
+    well. Since that aggregate is cumulative, the entries of one session and
+    model are keyed identically, which bills only the final one.  */
+function * scanCopilot (month: string, since: number): Generator<Call> {
+    const root = path.join(rootDir("COPILOT_CONFIG_DIR", ".copilot"), "session-state")
+    for (const file of filesBelow(root, (n) => n.endsWith(".jsonl"))) {
+        for (const { obj } of records(file, since)) {
+            const metrics = obj?.modelMetrics
+            if (typeof metrics !== "object" || metrics === null)
+                continue
+            const at = parseTime(obj?.timestamp)
+            if (at === null || monthKeyOf(at) !== month)
+                continue
+            for (const [ model, entry ] of Object.entries<any>(metrics)) {
+                const usage = entry?.usage ?? entry
+                if (typeof usage !== "object" || usage === null)
+                    continue
+                const cacheRead  = usage.cacheReadTokens  ?? 0
+                const cacheWrite = usage.cacheWriteTokens ?? 0
+                const u = noUsage()
+                u.input        = Math.max(0, (usage.inputTokens ?? 0) - cacheRead - cacheWrite)
+                u.output       = (usage.outputTokens ?? 0) + (usage.reasoningTokens ?? 0)
+                u.cacheRead    = cacheRead
+                u.cacheWrite5m = cacheWrite
+                yield { key: `copilot:${file}:${model}`, model, usage: u }
+            }
+        }
+    }
+}
+
+/*  all supported agent tools, scanned in one pass  */
+const scanners = [ scanClaude, scanCodex, scanCopilot ]
+
+/*  per-user cache file in the temporary directory  */
+const cacheFile = (): string => {
+    let user: string
+    try {
+        user = os.userInfo().username || "default"
+    }
+    catch (_e) {
+        user = process.env.USER ?? "default"
+    }
+    return path.join(os.tmpdir(), `ase-statusline-month-cost-${user}.json`)
+}
+
+/*  read the persisted month-cost cache, or null when absent, unreadable, or
+    written by an ASE with a different computation scheme  */
+export const readMonthCostCache = (): MonthCostCache | null => {
+    try {
+        const obj = JSON.parse(fs.readFileSync(cacheFile(), "utf8")) as MonthCostCache
+        if (obj.version === SCHEME
+            && typeof obj.month === "string"
+            && typeof obj.costUsd === "number"
+            && typeof obj.computedAt === "number")
+            return obj
+        return null
+    }
+    catch (_e) {
+        return null
+    }
+}
+
+const writeMonthCostCache = (cache: MonthCostCache): void => {
+    try {
+        fs.writeFileSync(cacheFile(), JSON.stringify(cache), "utf8")
+    }
+    catch (_e) {
+        /*  best-effort: a non-writable temp directory just means no caching  */
+    }
+}
+
+/*  scan the local session logs of every supported agent tool and sum the cost
+    of all calls billed within the given UTC month. Calls that were logged
+    more than once are billed once, keeping the most expensive of their
+    snapshots: the usage counts of a call grow while its response streams, so
+    the largest snapshot reflects the finally billed state. Missing or
+    unreadable logs simply contribute 0 without throwing.  */
+export const computeMonthCost = (now: Date): number => {
+    const month = monthKeyOf(now)
+    const since = startOfMonth(now)
+    const seen  = new Map<string, number>()
+    for (const scan of scanners) {
+        for (const call of scan(month, since)) {
+            const cost = costOf(call)
+            if (cost > (seen.get(call.key) ?? -1))
+                seen.set(call.key, cost)
+        }
+    }
+    let total = 0
+    for (const cost of seen.values())
+        total += cost
+    return total
+}
+
+/*  recompute the current-month cost and persist it to the cache file  */
+export const refreshMonthCostCache = (now: Date): void => {
+    writeMonthCostCache({
+        version:    SCHEME,
+        month:      monthKeyOf(now),
+        costUsd:    computeMonthCost(now),
+        computedAt: now.getTime()
+    })
+}
+
+/*  spawn a detached background process that recomputes the cache without
+    blocking the current statusline render; any failure is swallowed since a
+    missed refresh only means the next render keeps using the stale value  */
+const spawnMonthCostRefresh = (): void => {
+    try {
+        const entry = process.argv[1]
+        if (entry === undefined)
+            return
+        const child = spawn(process.execPath, [ entry, "statusline", "--refresh-month-cost" ],
+            { detached: true, stdio: "ignore" })
+        child.unref()
+    }
+    catch (_e) {
+        /*  unable to spawn: keep serving the last cached value  */
+    }
+}
+
+/*  resolve the value to render for the %Y current-month cost placeholder:
+    returns the cached cost when it is for the current month, and triggers a
+    non-blocking background refresh whenever the cache is missing, stale
+    (older than ttlSec), or from a previous month. Returns null when there is
+    no usable current-month value yet (first run, or no logged usage).  */
+export const monthCostForRender = (now: Date, ttlSec: number): number | null => {
+    const month = monthKeyOf(now)
+    const cache = readMonthCostCache()
+    const fresh = cache !== null
+        && cache.month === month
+        && now.getTime() - cache.computedAt < ttlSec * 1000
+    if (!fresh)
+        spawnMonthCostRefresh()
+    if (cache !== null && cache.month === month && cache.costUsd > 0)
+        return cache.costUsd
+    return null
+}
diff --git a/tool/src/ase-statusline-prices.ts b/tool/src/ase-statusline-prices.ts
new file mode 100644
index 00000000..696451a7
--- /dev/null
+++ b/tool/src/ase-statusline-prices.ts
@@ -0,0 +1,289 @@
+/*
+**  Agentic Software Engineering (ASE)
+**  Copyright (c) 2025-2026 Dr. Ralf S. Engelschall <rse@engelschall.com>
+**  Licensed under GPL 3.0 <https://spdx.org/licenses/GPL-3.0-only>
+*/
+
+/*  GENERATED FILE -- do NOT edit manually.
+    Regenerate with "npm start prices-update" (see etc/litellm-prices.mjs).
+    Source: https://raw.githubusercontent.com/BerriAI/litellm/main/model_prices_and_context_window.json  */
+
+/*  per-model token prices in USD per single token, as the tuple
+    [ input, output, cache-read, cache-write (5m), cache-write (1h) ]  */
+export type Price = readonly [ number, number, number, number, number ]
+
+export const prices: Readonly<Record<string, Price>> = {
+    "chatgpt-4o-latest": [ 0.000005, 0.000015, 0.000005, 0, 0 ],
+    "claude-3-7-sonnet-20250219": [ 0.000003, 0.000015, 3e-7, 0.00000375, 0.000006 ],
+    "claude-3-haiku-20240307": [ 2.5e-7, 0.00000125, 3e-8, 3e-7, 0.000006 ],
+    "claude-3-opus-20240229": [ 0.000015, 0.000075, 0.0000015, 0.00001875, 0.000006 ],
+    "claude-4-opus-20250514": [ 0.000015, 0.000075, 0.0000015, 0.00001875, 0.00001875 ],
+    "claude-4-sonnet-20250514": [ 0.000003, 0.000015, 3e-7, 0.00000375, 0.00000375 ],
+    "claude-fable-5": [ 0.00001, 0.00005, 0.000001, 0.0000125, 0.00002 ],
+    "claude-haiku-4-5": [ 0.000001, 0.000005, 1e-7, 0.00000125, 0.000002 ],
+    "claude-haiku-4-5-20251001": [ 0.000001, 0.000005, 1e-7, 0.00000125, 0.000002 ],
+    "claude-opus-4-1": [ 0.000015, 0.000075, 0.0000015, 0.00001875, 0.00003 ],
+    "claude-opus-4-1-20250805": [ 0.000015, 0.000075, 0.0000015, 0.00001875, 0.00003 ],
+    "claude-opus-4-20250514": [ 0.000015, 0.000075, 0.0000015, 0.00001875, 0.00003 ],
+    "claude-opus-4-5": [ 0.000005, 0.000025, 5e-7, 0.00000625, 0.00001 ],
+    "claude-opus-4-5-20251101": [ 0.000005, 0.000025, 5e-7, 0.00000625, 0.00001 ],
+    "claude-opus-4-6": [ 0.000005, 0.000025, 5e-7, 0.00000625, 0.00001 ],
+    "claude-opus-4-6-20260205": [ 0.000005, 0.000025, 5e-7, 0.00000625, 0.00001 ],
+    "claude-opus-4-7": [ 0.000005, 0.000025, 5e-7, 0.00000625, 0.00001 ],
+    "claude-opus-4-7-20260416": [ 0.000005, 0.000025, 5e-7, 0.00000625, 0.00001 ],
+    "claude-opus-4-8": [ 0.000005, 0.000025, 5e-7, 0.00000625, 0.00001 ],
+    "claude-opus-5": [ 0.000005, 0.000025, 5e-7, 0.00000625, 0.00001 ],
+    "claude-sonnet-4-20250514": [ 0.000003, 0.000015, 3e-7, 0.00000375, 0.000006 ],
+    "claude-sonnet-4-5": [ 0.000003, 0.000015, 3e-7, 0.00000375, 0.000006 ],
+    "claude-sonnet-4-5-20250929": [ 0.000003, 0.000015, 3e-7, 0.00000375, 0.000006 ],
+    "claude-sonnet-4-6": [ 0.000003, 0.000015, 3e-7, 0.00000375, 0.000006 ],
+    "claude-sonnet-5": [ 0.000002, 0.00001, 2e-7, 0.0000025, 0.000004 ],
+    "codestral-2405": [ 0.000001, 0.000003, 0.000001, 0, 0 ],
+    "codestral-2508": [ 3e-7, 9e-7, 3e-7, 0, 0 ],
+    "codestral-latest": [ 0.000001, 0.000003, 0.000001, 0, 0 ],
+    "codestral-mamba-latest": [ 2.5e-7, 2.5e-7, 2.5e-7, 0, 0 ],
+    "codex-mini-latest": [ 0.0000015, 0.000006, 3.75e-7, 0, 0 ],
+    "deepseek-chat": [ 2.8e-7, 4.2e-7, 2.8e-8, 0, 0 ],
+    "deepseek-coder": [ 1.4e-7, 2.8e-7, 1.4e-7, 0, 0 ],
+    "deepseek-r1": [ 5.5e-7, 0.00000219, 5.5e-7, 0, 0 ],
+    "deepseek-reasoner": [ 2.8e-7, 4.2e-7, 2.8e-8, 0, 0 ],
+    "deepseek-v3": [ 2.7e-7, 0.0000011, 7e-8, 0, 0 ],
+    "deepseek-v3.2": [ 2.8e-7, 4e-7, 2.8e-7, 0, 0 ],
+    "deepseek-v4-flash": [ 1.4e-7, 2.8e-7, 2.8e-9, 0, 0 ],
+    "deepseek-v4-pro": [ 4.35e-7, 8.7e-7, 3.625e-9, 0, 0 ],
+    "devstral-2512": [ 4e-7, 0.000002, 4e-7, 0, 0 ],
+    "devstral-latest": [ 4e-7, 0.000002, 4e-7, 0, 0 ],
+    "devstral-medium-2507": [ 4e-7, 0.000002, 4e-7, 0, 0 ],
+    "devstral-medium-latest": [ 4e-7, 0.000002, 4e-7, 0, 0 ],
+    "devstral-small-2505": [ 1e-7, 3e-7, 1e-7, 0, 0 ],
+    "devstral-small-2507": [ 1e-7, 3e-7, 1e-7, 0, 0 ],
+    "devstral-small-latest": [ 1e-7, 3e-7, 1e-7, 0, 0 ],
+    "ft:gpt-3.5-turbo": [ 0.000003, 0.000006, 0.000003, 0, 0 ],
+    "ft:gpt-3.5-turbo-0125": [ 0.000003, 0.000006, 0.000003, 0, 0 ],
+    "ft:gpt-3.5-turbo-0613": [ 0.000003, 0.000006, 0.000003, 0, 0 ],
+    "ft:gpt-3.5-turbo-1106": [ 0.000003, 0.000006, 0.000003, 0, 0 ],
+    "ft:gpt-4-0613": [ 0.00003, 0.00006, 0.00003, 0, 0 ],
+    "ft:gpt-4.1-2025-04-14": [ 0.000003, 0.000012, 7.5e-7, 0, 0 ],
+    "ft:gpt-4.1-mini-2025-04-14": [ 8e-7, 0.0000032, 2e-7, 0, 0 ],
+    "ft:gpt-4.1-nano-2025-04-14": [ 2e-7, 8e-7, 5e-8, 0, 0 ],
+    "ft:gpt-4o-2024-08-06": [ 0.00000375, 0.000015, 0.000001875, 0, 0 ],
+    "ft:gpt-4o-2024-11-20": [ 0.00000375, 0.000015, 0.00000375, 0.000001875, 0.000001875 ],
+    "ft:gpt-4o-mini-2024-07-18": [ 3e-7, 0.0000012, 1.5e-7, 0, 0 ],
+    "ft:o4-mini-2025-04-16": [ 0.000004, 0.000016, 0.000001, 0, 0 ],
+    "gemini-2.0-flash": [ 1e-7, 4e-7, 2.5e-8, 0, 0 ],
+    "gemini-2.0-flash-001": [ 1e-7, 4e-7, 2.5e-8, 0, 0 ],
+    "gemini-2.0-flash-lite": [ 7.5e-8, 3e-7, 1.875e-8, 0, 0 ],
+    "gemini-2.0-flash-lite-001": [ 7.5e-8, 3e-7, 1.875e-8, 0, 0 ],
+    "gemini-2.5-computer-use-preview-10-2025": [ 0.00000125, 0.00001, 0.00000125, 0, 0 ],
+    "gemini-2.5-flash": [ 3e-7, 0.0000025, 3e-8, 0, 0 ],
+    "gemini-2.5-flash-lite": [ 1e-7, 4e-7, 1e-8, 0, 0 ],
+    "gemini-2.5-flash-lite-preview-06-17": [ 1e-7, 4e-7, 2.5e-8, 0, 0 ],
+    "gemini-2.5-flash-lite-preview-09-2025": [ 1e-7, 4e-7, 1e-8, 0, 0 ],
+    "gemini-2.5-flash-native-audio-latest": [ 3e-7, 0.0000025, 3e-7, 0, 0 ],
+    "gemini-2.5-flash-native-audio-preview-09-2025": [ 3e-7, 0.0000025, 3e-7, 0, 0 ],
+    "gemini-2.5-flash-native-audio-preview-12-2025": [ 3e-7, 0.0000025, 3e-7, 0, 0 ],
+    "gemini-2.5-flash-preview-09-2025": [ 3e-7, 0.0000025, 7.5e-8, 0, 0 ],
+    "gemini-2.5-pro": [ 0.00000125, 0.00001, 1.25e-7, 0, 0 ],
+    "gemini-2.5-pro-preview-tts": [ 0.00000125, 0.00001, 1.25e-7, 0, 0 ],
+    "gemini-3-flash-preview": [ 5e-7, 0.000003, 5e-8, 0, 0 ],
+    "gemini-3-pro-preview": [ 0.000002, 0.000012, 2e-7, 0, 0 ],
+    "gemini-3.1-flash-lite": [ 2.5e-7, 0.0000015, 2.5e-8, 0, 0 ],
+    "gemini-3.1-flash-lite-preview": [ 2.5e-7, 0.0000015, 2.5e-8, 0, 0 ],
+    "gemini-3.1-flash-live-preview": [ 7.5e-7, 0.0000045, 7.5e-7, 0, 0 ],
+    "gemini-3.1-pro-preview": [ 0.000002, 0.000012, 2e-7, 0, 0 ],
+    "gemini-3.1-pro-preview-customtools": [ 0.000002, 0.000012, 2e-7, 0, 0 ],
+    "gemini-3.5-flash": [ 0.0000015, 0.000009, 1.5e-7, 0, 0 ],
+    "gemini-3.5-flash-lite": [ 3e-7, 0.0000025, 3e-8, 0, 0 ],
+    "gemini-3.6-flash": [ 0.0000015, 0.0000075, 1.5e-7, 0, 0 ],
+    "gemini-exp-1114": [ 0, 0, 0, 0, 0 ],
+    "gemini-exp-1206": [ 3e-7, 0.0000025, 3e-8, 0, 0 ],
+    "gemini-flash-latest": [ 3e-7, 0.0000025, 3e-8, 0, 0 ],
+    "gemini-flash-lite-latest": [ 1e-7, 4e-7, 1e-8, 0, 0 ],
+    "gemini-gemma-2-27b-it": [ 3.5e-7, 0.00000105, 3.5e-7, 0, 0 ],
+    "gemini-gemma-2-9b-it": [ 3.5e-7, 0.00000105, 3.5e-7, 0, 0 ],
+    "gemini-omni-flash-preview": [ 0.0000015, 0.000009, 0.0000015, 0, 0 ],
+    "gemini-pro-latest": [ 0.00000125, 0.00001, 1.25e-7, 0, 0 ],
+    "gemini-robotics-er-1.5-preview": [ 3e-7, 0.0000025, 0, 0, 0 ],
+    "gemma-3-27b-it": [ 0, 0, 0, 0, 0 ],
+    "gpt-3.5-turbo": [ 5e-7, 0.0000015, 5e-7, 0, 0 ],
+    "gpt-3.5-turbo-0125": [ 5e-7, 0.0000015, 5e-7, 0, 0 ],
+    "gpt-3.5-turbo-1106": [ 0.000001, 0.000002, 0.000001, 0, 0 ],
+    "gpt-3.5-turbo-16k": [ 0.000003, 0.000004, 0.000003, 0, 0 ],
+    "gpt-4": [ 0.00003, 0.00006, 0.00003, 0, 0 ],
+    "gpt-4-0125-preview": [ 0.00001, 0.00003, 0.00001, 0, 0 ],
+    "gpt-4-0314": [ 0.00003, 0.00006, 0.00003, 0, 0 ],
+    "gpt-4-0613": [ 0.00003, 0.00006, 0.00003, 0, 0 ],
+    "gpt-4-1106-preview": [ 0.00001, 0.00003, 0.00001, 0, 0 ],
+    "gpt-4-turbo": [ 0.00001, 0.00003, 0.00001, 0, 0 ],
+    "gpt-4-turbo-2024-04-09": [ 0.00001, 0.00003, 0.00001, 0, 0 ],
+    "gpt-4-turbo-preview": [ 0.00001, 0.00003, 0.00001, 0, 0 ],
+    "gpt-4.1": [ 0.000002, 0.000008, 5e-7, 0, 0 ],
+    "gpt-4.1-2025-04-14": [ 0.000002, 0.000008, 5e-7, 0, 0 ],
+    "gpt-4.1-mini": [ 4e-7, 0.0000016, 1e-7, 0, 0 ],
+    "gpt-4.1-mini-2025-04-14": [ 4e-7, 0.0000016, 1e-7, 0, 0 ],
+    "gpt-4.1-nano": [ 1e-7, 4e-7, 2.5e-8, 0, 0 ],
+    "gpt-4.1-nano-2025-04-14": [ 1e-7, 4e-7, 2.5e-8, 0, 0 ],
+    "gpt-4o": [ 0.0000025, 0.00001, 0.00000125, 0, 0 ],
+    "gpt-4o-2024-05-13": [ 0.000005, 0.000015, 0.000005, 0, 0 ],
+    "gpt-4o-2024-08-06": [ 0.0000025, 0.00001, 0.00000125, 0, 0 ],
+    "gpt-4o-2024-11-20": [ 0.0000025, 0.00001, 0.00000125, 0, 0 ],
+    "gpt-4o-audio-preview": [ 0.0000025, 0.00001, 0.0000025, 0, 0 ],
+    "gpt-4o-audio-preview-2024-12-17": [ 0.0000025, 0.00001, 0.0000025, 0, 0 ],
+    "gpt-4o-audio-preview-2025-06-03": [ 0.0000025, 0.00001, 0.0000025, 0, 0 ],
+    "gpt-4o-mini": [ 1.5e-7, 6e-7, 7.5e-8, 0, 0 ],
+    "gpt-4o-mini-2024-07-18": [ 1.5e-7, 6e-7, 7.5e-8, 0, 0 ],
+    "gpt-4o-mini-audio-preview": [ 1.5e-7, 6e-7, 1.5e-7, 0, 0 ],
+    "gpt-4o-mini-audio-preview-2024-12-17": [ 1.5e-7, 6e-7, 1.5e-7, 0, 0 ],
+    "gpt-4o-mini-search-preview": [ 1.5e-7, 6e-7, 7.5e-8, 0, 0 ],
+    "gpt-4o-mini-search-preview-2025-03-11": [ 1.5e-7, 6e-7, 7.5e-8, 0, 0 ],
+    "gpt-4o-search-preview": [ 0.0000025, 0.00001, 0.00000125, 0, 0 ],
+    "gpt-4o-search-preview-2025-03-11": [ 0.0000025, 0.00001, 0.00000125, 0, 0 ],
+    "gpt-5": [ 0.00000125, 0.00001, 1.25e-7, 0, 0 ],
+    "gpt-5-2025-08-07": [ 0.00000125, 0.00001, 1.25e-7, 0, 0 ],
+    "gpt-5-chat": [ 0.00000125, 0.00001, 1.25e-7, 0, 0 ],
+    "gpt-5-chat-latest": [ 0.00000125, 0.00001, 1.25e-7, 0, 0 ],
+    "gpt-5-codex": [ 0.00000125, 0.00001, 1.25e-7, 0, 0 ],
+    "gpt-5-mini": [ 2.5e-7, 0.000002, 2.5e-8, 0, 0 ],
+    "gpt-5-mini-2025-08-07": [ 2.5e-7, 0.000002, 2.5e-8, 0, 0 ],
+    "gpt-5-nano": [ 5e-8, 4e-7, 5e-9, 0, 0 ],
+    "gpt-5-nano-2025-08-07": [ 5e-8, 4e-7, 5e-9, 0, 0 ],
+    "gpt-5-pro": [ 0.000015, 0.00012, 0.000015, 0, 0 ],
+    "gpt-5-pro-2025-10-06": [ 0.000015, 0.00012, 0.000015, 0, 0 ],
+    "gpt-5-search-api": [ 0.00000125, 0.00001, 1.25e-7, 0, 0 ],
+    "gpt-5-search-api-2025-10-14": [ 0.00000125, 0.00001, 1.25e-7, 0, 0 ],
+    "gpt-5.1": [ 0.00000125, 0.00001, 1.25e-7, 0, 0 ],
+    "gpt-5.1-2025-11-13": [ 0.00000125, 0.00001, 1.25e-7, 0, 0 ],
+    "gpt-5.1-chat-latest": [ 0.00000125, 0.00001, 1.25e-7, 0, 0 ],
+    "gpt-5.1-codex": [ 0.00000125, 0.00001, 1.25e-7, 0, 0 ],
+    "gpt-5.1-codex-max": [ 0.00000125, 0.00001, 1.25e-7, 0, 0 ],
+    "gpt-5.1-codex-mini": [ 2.5e-7, 0.000002, 2.5e-8, 0, 0 ],
+    "gpt-5.2": [ 0.00000175, 0.000014, 1.75e-7, 0, 0 ],
+    "gpt-5.2-2025-12-11": [ 0.00000175, 0.000014, 1.75e-7, 0, 0 ],
+    "gpt-5.2-chat-latest": [ 0.00000175, 0.000014, 1.75e-7, 0, 0 ],
+    "gpt-5.2-codex": [ 0.00000175, 0.000014, 1.75e-7, 0, 0 ],
+    "gpt-5.2-pro": [ 0.000021, 0.000168, 0.000021, 0, 0 ],
+    "gpt-5.2-pro-2025-12-11": [ 0.000021, 0.000168, 0.000021, 0, 0 ],
+    "gpt-5.3-chat-latest": [ 0.00000175, 0.000014, 1.75e-7, 0, 0 ],
+    "gpt-5.3-codex": [ 0.00000175, 0.000014, 1.75e-7, 0, 0 ],
+    "gpt-5.4": [ 0.0000025, 0.000015, 2.5e-7, 0, 0 ],
+    "gpt-5.4-2026-03-05": [ 0.0000025, 0.000015, 2.5e-7, 0, 0 ],
+    "gpt-5.4-mini": [ 7.5e-7, 0.0000045, 7.5e-8, 0, 0 ],
+    "gpt-5.4-mini-2026-03-17": [ 7.5e-7, 0.0000045, 7.5e-8, 0, 0 ],
+    "gpt-5.4-nano": [ 2e-7, 0.00000125, 2e-8, 0, 0 ],
+    "gpt-5.4-nano-2026-03-17": [ 2e-7, 0.00000125, 2e-8, 0, 0 ],
+    "gpt-5.4-pro": [ 0.00003, 0.00018, 0.000003, 0, 0 ],
+    "gpt-5.4-pro-2026-03-05": [ 0.00003, 0.00018, 0.000003, 0, 0 ],
+    "gpt-5.5": [ 0.000005, 0.00003, 5e-7, 0, 0 ],
+    "gpt-5.5-2026-04-23": [ 0.000005, 0.00003, 5e-7, 0, 0 ],
+    "gpt-5.5-pro": [ 0.00003, 0.00018, 0.000003, 0, 0 ],
+    "gpt-5.5-pro-2026-04-23": [ 0.00003, 0.00018, 0.000003, 0, 0 ],
+    "gpt-5.6": [ 0.000005, 0.00003, 5e-7, 0.00000625, 0.00000625 ],
+    "gpt-5.6-luna": [ 2e-7, 0.0000012, 2e-8, 2.5e-7, 2.5e-7 ],
+    "gpt-5.6-sol": [ 0.000005, 0.00003, 5e-7, 0.00000625, 0.00000625 ],
+    "gpt-5.6-terra": [ 0.000002, 0.000012, 2e-7, 0.0000025, 0.0000025 ],
+    "gpt-audio": [ 0.0000025, 0.00001, 0.0000025, 0, 0 ],
+    "gpt-audio-1.5": [ 0.0000025, 0.00001, 0.0000025, 0, 0 ],
+    "gpt-audio-2025-08-28": [ 0.0000025, 0.00001, 0.0000025, 0, 0 ],
+    "gpt-audio-mini": [ 6e-7, 0.0000024, 6e-7, 0, 0 ],
+    "gpt-audio-mini-2025-10-06": [ 6e-7, 0.0000024, 6e-7, 0, 0 ],
+    "gpt-audio-mini-2025-12-15": [ 6e-7, 0.0000024, 6e-7, 0, 0 ],
+    "grok-2": [ 0.000002, 0.00001, 0.000002, 0, 0 ],
+    "grok-2-1212": [ 0.000002, 0.00001, 0.000002, 0, 0 ],
+    "grok-2-latest": [ 0.000002, 0.00001, 0.000002, 0, 0 ],
+    "grok-2-vision": [ 0.000002, 0.00001, 0.000002, 0, 0 ],
+    "grok-2-vision-1212": [ 0.000002, 0.00001, 0.000002, 0, 0 ],
+    "grok-2-vision-latest": [ 0.000002, 0.00001, 0.000002, 0, 0 ],
+    "grok-3": [ 0.000003, 0.000015, 7.5e-7, 0, 0 ],
+    "grok-3-beta": [ 0.000003, 0.000015, 7.5e-7, 0, 0 ],
+    "grok-3-fast-beta": [ 0.000005, 0.000025, 0.00000125, 0, 0 ],
+    "grok-3-fast-latest": [ 0.000005, 0.000025, 0.00000125, 0, 0 ],
+    "grok-3-latest": [ 0.000003, 0.000015, 7.5e-7, 0, 0 ],
+    "grok-3-mini": [ 3e-7, 5e-7, 7.5e-8, 0, 0 ],
+    "grok-3-mini-beta": [ 3e-7, 5e-7, 7.5e-8, 0, 0 ],
+    "grok-3-mini-fast": [ 6e-7, 0.000004, 1.5e-7, 0, 0 ],
+    "grok-3-mini-fast-beta": [ 6e-7, 0.000004, 1.5e-7, 0, 0 ],
+    "grok-3-mini-fast-latest": [ 6e-7, 0.000004, 1.5e-7, 0, 0 ],
+    "grok-3-mini-latest": [ 3e-7, 5e-7, 7.5e-8, 0, 0 ],
+    "grok-4": [ 0.000003, 0.000015, 0.000003, 0, 0 ],
+    "grok-4-0709": [ 0.000003, 0.000015, 0.000003, 0, 0 ],
+    "grok-4-1-fast": [ 2e-7, 5e-7, 5e-8, 0, 0 ],
+    "grok-4-1-fast-non-reasoning": [ 2e-7, 5e-7, 5e-8, 0, 0 ],
+    "grok-4-1-fast-non-reasoning-latest": [ 2e-7, 5e-7, 5e-8, 0, 0 ],
+    "grok-4-1-fast-reasoning": [ 2e-7, 5e-7, 5e-8, 0, 0 ],
+    "grok-4-1-fast-reasoning-latest": [ 2e-7, 5e-7, 5e-8, 0, 0 ],
+    "grok-4-fast-non-reasoning": [ 2e-7, 5e-7, 5e-8, 0, 0 ],
+    "grok-4-fast-reasoning": [ 2e-7, 5e-7, 5e-8, 0, 0 ],
+    "grok-4-latest": [ 0.000003, 0.000015, 0.000003, 0, 0 ],
+    "grok-4.20-0309-reasoning": [ 0.000002, 0.000006, 2e-7, 0, 0 ],
+    "grok-4.20-beta-0309-non-reasoning": [ 0.000002, 0.000006, 2e-7, 0, 0 ],
+    "grok-4.20-beta-0309-reasoning": [ 0.000002, 0.000006, 2e-7, 0, 0 ],
+    "grok-4.20-multi-agent-beta-0309": [ 0.000002, 0.000006, 2e-7, 0, 0 ],
+    "grok-4.3": [ 0.00000125, 0.0000025, 2e-7, 0, 0 ],
+    "grok-4.3-latest": [ 0.00000125, 0.0000025, 2e-7, 0, 0 ],
+    "grok-4.5": [ 0.000002, 0.000006, 5e-7, 0, 0 ],
+    "grok-4.5-latest": [ 0.000002, 0.000006, 5e-7, 0, 0 ],
+    "grok-beta": [ 0.000005, 0.000015, 0.000005, 0, 0 ],
+    "grok-code-fast": [ 2e-7, 0.0000015, 2e-8, 0, 0 ],
+    "grok-code-fast-1": [ 2e-7, 0.0000015, 2e-8, 0, 0 ],
+    "grok-code-fast-1-0825": [ 2e-7, 0.0000015, 2e-8, 0, 0 ],
+    "grok-vision-beta": [ 0.000005, 0.000015, 0.000005, 0, 0 ],
+    "labs-devstral-small-2512": [ 1e-7, 3e-7, 1e-7, 0, 0 ],
+    "learnlm-1.5-pro-experimental": [ 0, 0, 0, 0, 0 ],
+    "lyria-3-clip-preview": [ 0, 0, 0, 0, 0 ],
+    "lyria-3-pro-preview": [ 0, 0, 0, 0, 0 ],
+    "magistral-medium-1-2-2509": [ 0.000002, 0.000005, 0.000002, 0, 0 ],
+    "magistral-medium-2506": [ 0.000002, 0.000005, 0.000002, 0, 0 ],
+    "magistral-medium-2509": [ 0.000002, 0.000005, 0.000002, 0, 0 ],
+    "magistral-medium-latest": [ 0.000002, 0.000005, 0.000002, 0, 0 ],
+    "magistral-small-1-2-2509": [ 5e-7, 0.0000015, 5e-7, 0, 0 ],
+    "magistral-small-2506": [ 5e-7, 0.0000015, 5e-7, 0, 0 ],
+    "magistral-small-latest": [ 5e-7, 0.0000015, 5e-7, 0, 0 ],
+    "ministral-3-14b-2512": [ 2e-7, 2e-7, 2e-7, 0, 0 ],
+    "ministral-3-3b-2512": [ 1e-7, 1e-7, 1e-7, 0, 0 ],
+    "ministral-3-8b-2512": [ 1.5e-7, 1.5e-7, 1.5e-7, 0, 0 ],
+    "ministral-8b-2512": [ 1.5e-7, 1.5e-7, 1.5e-7, 0, 0 ],
+    "ministral-8b-latest": [ 1.5e-7, 1.5e-7, 1.5e-7, 0, 0 ],
+    "mistral-large-2402": [ 0.000004, 0.000012, 0.000004, 0, 0 ],
+    "mistral-large-2407": [ 0.000003, 0.000009, 0.000003, 0, 0 ],
+    "mistral-large-2411": [ 0.000002, 0.000006, 0.000002, 0, 0 ],
+    "mistral-large-2512": [ 5e-7, 0.0000015, 5e-7, 0, 0 ],
+    "mistral-large-3": [ 5e-7, 0.0000015, 5e-7, 0, 0 ],
+    "mistral-large-latest": [ 5e-7, 0.0000015, 5e-7, 0, 0 ],
+    "mistral-medium": [ 0.0000027, 0.0000081, 0.0000027, 0, 0 ],
+    "mistral-medium-2312": [ 0.0000027, 0.0000081, 0.0000027, 0, 0 ],
+    "mistral-medium-2505": [ 4e-7, 0.000002, 4e-7, 0, 0 ],
+    "mistral-medium-2508": [ 4e-7, 0.000002, 4e-7, 0, 0 ],
+    "mistral-medium-2604": [ 0.0000015, 0.0000075, 0.0000015, 0, 0 ],
+    "mistral-medium-3-1-2508": [ 4e-7, 0.000002, 4e-7, 0, 0 ],
+    "mistral-medium-3-5": [ 0.0000015, 0.0000075, 0.0000015, 0, 0 ],
+    "mistral-medium-latest": [ 0.0000015, 0.0000075, 0.0000015, 0, 0 ],
+    "mistral-small": [ 1e-7, 3e-7, 1e-7, 0, 0 ],
+    "mistral-small-3-2-2506": [ 6e-8, 1.8e-7, 6e-8, 0, 0 ],
+    "mistral-small-latest": [ 6e-8, 1.8e-7, 6e-8, 0, 0 ],
+    "mistral-tiny": [ 2.5e-7, 2.5e-7, 2.5e-7, 0, 0 ],
+    "o1": [ 0.000015, 0.00006, 0.0000075, 0, 0 ],
+    "o1-2024-12-17": [ 0.000015, 0.00006, 0.0000075, 0, 0 ],
+    "o1-pro": [ 0.00015, 0.0006, 0.00015, 0, 0 ],
+    "o1-pro-2025-03-19": [ 0.00015, 0.0006, 0.00015, 0, 0 ],
+    "o3": [ 0.000002, 0.000008, 5e-7, 0, 0 ],
+    "o3-2025-04-16": [ 0.000002, 0.000008, 5e-7, 0, 0 ],
+    "o3-deep-research": [ 0.00001, 0.00004, 0.0000025, 0, 0 ],
+    "o3-deep-research-2025-06-26": [ 0.00001, 0.00004, 0.0000025, 0, 0 ],
+    "o3-mini": [ 0.0000011, 0.0000044, 5.5e-7, 0, 0 ],
+    "o3-mini-2025-01-31": [ 0.0000011, 0.0000044, 5.5e-7, 0, 0 ],
+    "o3-pro": [ 0.00002, 0.00008, 0.00002, 0, 0 ],
+    "o3-pro-2025-06-10": [ 0.00002, 0.00008, 0.00002, 0, 0 ],
+    "o4-mini": [ 0.0000011, 0.0000044, 2.75e-7, 0, 0 ],
+    "o4-mini-2025-04-16": [ 0.0000011, 0.0000044, 2.75e-7, 0, 0 ],
+    "o4-mini-deep-research": [ 0.000002, 0.000008, 5e-7, 0, 0 ],
+    "o4-mini-deep-research-2025-06-26": [ 0.000002, 0.000008, 5e-7, 0, 0 ],
+    "open-codestral-mamba": [ 2.5e-7, 2.5e-7, 2.5e-7, 0, 0 ],
+    "open-mistral-7b": [ 2.5e-7, 2.5e-7, 2.5e-7, 0, 0 ],
+    "open-mistral-nemo": [ 3e-7, 3e-7, 3e-7, 0, 0 ],
+    "open-mistral-nemo-2407": [ 3e-7, 3e-7, 3e-7, 0, 0 ],
+    "open-mixtral-8x22b": [ 0.000002, 0.000006, 0.000002, 0, 0 ],
+    "open-mixtral-8x7b": [ 7e-7, 7e-7, 7e-7, 0, 0 ],
+    "pixtral-12b-2409": [ 1.5e-7, 1.5e-7, 1.5e-7, 0, 0 ],
+    "pixtral-large-2411": [ 0.000002, 0.000006, 0.000002, 0, 0 ],
+    "pixtral-large-latest": [ 0.000002, 0.000006, 0.000002, 0, 0 ]
+}
diff --git a/tool/src/ase-statusline.ts b/tool/src/ase-statusline.ts
index d6baae44..101b8a12 100644
--- a/tool/src/ase-statusline.ts
+++ b/tool/src/ase-statusline.ts
@@ -17,6 +17,7 @@ import type { ForegroundColorName }         from "chalk"
 import type Log                             from "./ase-log.js"
 import { Config, configSchema, parseScope } from "./ase-config.js"
 import { readStdin, writeStdout }           from "./ase-stdio.js"
+import { monthCostForRender, refreshMonthCostCache } from "./ase-statusline-cost.js"
 import pkg                                  from "../package.json" with { type: "json" }
 
 /*  forced-color chalk instance: stdout is a pipe under Anthropic Claude Code CLI,
@@ -101,12 +102,14 @@ interface StatuslineInput {
 
 /*  internal command options type  */
 interface StatuslineOpts {
-    tool:    string
-    width:   number
-    margin:  number
-    padding: number
-    icons:   boolean
-    labels:  boolean
+    tool:             string
+    width:            number
+    margin:           number
+    padding:          number
+    icons:            boolean
+    labels:           boolean
+    monthCostTtl:     number
+    refreshMonthCost: boolean
 }
 
 /*  custom argument parser for Commander: non-negative integer  */
@@ -320,12 +323,25 @@ export default class StatuslineCommand {
                 "disable icons in placeholder rendering")
             .option("--no-labels",
                 "disable labels in front of bold values")
+            .option("--month-cost-ttl <n>",
+                "seconds to cache the %Y current-month total cost before a background refresh",
+                parseInteger("--month-cost-ttl"), 300)
+            .option("--refresh-month-cost",
+                "(internal) recompute and cache the current-month total cost, then exit")
             .argument("[lines...]",
                 "one or more template lines with %u %p %T %s %m %e %t %O %P %h %c %C %a %r " +
-                "%S %D %W %Q %H %X %b %g %G %d %M %V placeholders and <color>...</color> markup " +
+                "%S %D %W %Q %H %X %Y %b %g %G %d %M %V placeholders and <color>...</color> markup " +
                 "(color: black, red, green, yellow, blue, magenta, cyan, white, default) " +
                 "(default: single line \"%m %e %t\")")
             .action(async (lines: string[], opts: StatuslineOpts) => {
+                /*  internal mode: recompute the current-month cost cache and
+                    exit, as invoked by the detached background refresh that
+                    %Y spawns during a normal render (no stdin, no rendering)  */
+                if (opts.refreshMonthCost) {
+                    refreshMonthCostCache(new Date())
+                    return
+                }
+
                 /*  validate target tool  */
                 const tool = this.parseTool(opts.tool)
 
@@ -547,6 +563,11 @@ export default class StatuslineCommand {
                         if (sessCost !== undefined)
                             emit(`${prefix("$", "cost")}${c.bold(formatCostUsd(sessCost))}`)
                     },
+                    Y: () => {
+                        const monthCost = monthCostForRender(new Date(), opts.monthCostTtl)
+                        if (monthCost !== null)
+                            emit(`${prefix("∑", "month")}${c.bold(formatCostUsd(monthCost))}`)
+                    },
 
                     /*  ==== VERSION CONTROL ====  */
                     a: () => {