PyModel
diff --git a/‎.changeset/update-flow-reliability.md‎
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diff --git a/‎.changeset/update-minimum-supported-version.md‎
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diff --git a/‎.changeset/update-status-under-the-prompt.md‎
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diff --git a/‎apps/pythinker-code/src/cli/sub/upgrade.ts‎
Lines changed: 104 additions & 1 deletion b/‎apps/pythinker-code/src/cli/sub/upgrade.ts‎
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diff --git a/‎apps/pythinker-code/src/cli/update/cdn.ts‎
Lines changed: 92 additions & 44 deletions b/‎apps/pythinker-code/src/cli/update/cdn.ts‎
Lines changed: 92 additions & 44 deletions
@@ -0,0 +1,5 @@
+---
+"@pythoughts/pythinker-code": patch
+---
+
+Stop offering an update with no build for the running platform, give every installer network call a timeout, expire a stale install lease instead of blocking updates forever, and say which version is installing and why a failed one stopped retrying.
@@ -0,0 +1,5 @@
+---
+"@pythoughts/pythinker-code": minor
+---
+
+Let a release declare a minimum supported version, so a client below it is offered the update without waiting for its staged rollout batch.
@@ -0,0 +1,5 @@
+---
+"@pythoughts/pythinker-code": minor
+---
+
+Show update availability and live download progress in the status row under the prompt, replacing the startup banner chip that was computed once and never refreshed.
@@ -2,7 +2,16 @@ import { log, type Logger } from '@pythoughts/pythinker-code-sdk';
 import { track as trackTelemetry, type TelemetryProperties } from '@pythoughts/pythinker-telemetry';
 
 import { refreshUpdateCache } from '#/cli/update/refresh';
-import { selectUpdateTarget } from '#/cli/update/select';
+import { tryAcquireUpdateInstallLock } from '#/cli/update/install-lock';
+import type { UpdateInstallLockHandle, UpdateInstallLockRequest } from '#/cli/update/install-lock';
+import {
+  emptyUpdateInstallState,
+  failureAttemptsFor,
+  hasFreshActiveInstall,
+  readUpdateInstallState,
+  writeUpdateInstallState,
+} from '#/cli/update/install-state';
+import { isTargetInstallable, selectUpdateTarget } from '#/cli/update/select';
 import { detectInstallSource } from '#/cli/update/source';
 import {
   canAutoInstall,
@@ -20,6 +29,8 @@ import {
   NPM_PACKAGE_NAME,
   type InstallSource,
   type UpdateCache,
+  type UpdateInstallState,
+  type UpdateTarget,
 } from '#/cli/update/types';
 
 interface WritableLike {
@@ -40,6 +51,11 @@ export interface UpgradeDeps {
   readonly promptForInstallChoice: (
     options: InstallPromptOptions,
   ) => Promise<InstallPromptChoiceValue>;
+  readonly readUpdateInstallState: () => Promise<UpdateInstallState>;
+  readonly writeUpdateInstallState: (state: UpdateInstallState) => Promise<void>;
+  readonly tryAcquireUpdateInstallLock: (
+    request: UpdateInstallLockRequest,
+  ) => Promise<UpdateInstallLockHandle | null>;
   readonly platform: NodeJS.Platform;
   readonly stdout: WritableLike;
   readonly stderr: WritableLike;
@@ -85,6 +101,20 @@ export async function handleUpgrade(
   }
 
   const source = await deps.detectInstallSource().catch(() => 'unsupported' as const);
+  // A native install consumes the manifest's platform artifact; without one
+  // the update cannot succeed, so take the same exit as being up to date.
+  if (!isTargetInstallable(source, cache.manifest)) {
+    trackUpgradeEvent(deps.track, 'upgrade_command_no_update', {
+      current_version: currentVersion,
+    });
+    logUpgradeInfo(deps.logger, 'manual upgrade no update', {
+      currentVersion,
+    });
+    deps.stdout.write(
+      `${formatDisplayVersion(target.version)} is published but has no build for this platform yet.\n`,
+    );
+    return 0;
+  }
   const installCommand = installCommandFor(source, target.version, deps.platform);
   if (!canAutoInstall(source, deps.platform) || !deps.isInteractive) {
     trackUpgradeEvent(deps.track, 'upgrade_command_manual_command', {
@@ -131,13 +161,36 @@ export async function handleUpgrade(
     return 0;
   }
 
+  // The foreground install holds the update-install lock for its whole run:
+  // another live installer (usually a detached background one) must never be
+  // raced by this path, which writes the same executable. A fresh active
+  // record or a held lock means an install is already in flight — refuse.
+  const installState = await deps.readUpdateInstallState().catch(() => emptyUpdateInstallState());
+  if (hasFreshActiveInstall(installState)) {
+    return refuseForegroundInstall(deps, currentVersion, target, source, installState.active?.version);
+  }
+  const lock = await deps.tryAcquireUpdateInstallLock({ version: target.version });
+  if (lock === null) {
+    return refuseForegroundInstall(deps, currentVersion, target, source, undefined);
+  }
+
   try {
     trackUpgradeEvent(deps.track, 'upgrade_command_install_selected', {
       current_version: currentVersion,
       target_version: target.version,
       source,
     });
     await deps.installUpdate(source, target.version, deps.platform);
+    await deps.writeUpdateInstallState({
+      ...installState,
+      active: null,
+      lastFailure: null,
+      lastSuccess: {
+        version: target.version,
+        installedAt: nowIso(),
+        notifiedAt: null,
+      },
+    }).catch(() => {});
     trackUpgradeEvent(deps.track, 'upgrade_command_succeeded', {
       current_version: currentVersion,
       target_version: target.version,
@@ -151,6 +204,18 @@ export async function handleUpgrade(
     deps.stdout.write(renderInstallSuccessMessage(target));
     return 0;
   } catch (error) {
+    const attempts = failureAttemptsFor(installState, target, 'install') + 1;
+    await deps.writeUpdateInstallState({
+      ...installState,
+      active: null,
+      lastFailure: {
+        version: target.version,
+        failedAt: nowIso(),
+        attempts,
+        operation: 'install',
+        message: formatErrorMessage(error),
+      },
+    }).catch(() => {});
     trackUpgradeEvent(deps.track, 'upgrade_command_failed', {
       current_version: currentVersion,
       target_version: target.version,
@@ -169,6 +234,8 @@ export async function handleUpgrade(
         `${formatErrorMessage(error)}\n`,
     );
     return 1;
+  } finally {
+    await lock.release().catch(() => {});
   }
 }
 
@@ -178,6 +245,9 @@ function createDefaultUpgradeDeps(overrides: Partial<UpgradeDeps>): UpgradeDeps
     detectInstallSource: overrides.detectInstallSource ?? (() => detectInstallSource()),
     installUpdate: overrides.installUpdate ?? installUpdateForeground,
     promptForInstallChoice: overrides.promptForInstallChoice ?? promptForInstallChoice,
+    readUpdateInstallState: overrides.readUpdateInstallState ?? (() => readUpdateInstallState()),
+    writeUpdateInstallState: overrides.writeUpdateInstallState ?? writeUpdateInstallState,
+    tryAcquireUpdateInstallLock: overrides.tryAcquireUpdateInstallLock ?? tryAcquireUpdateInstallLock,
     platform: overrides.platform ?? process.platform,
     stdout: overrides.stdout ?? process.stdout,
     stderr: overrides.stderr ?? process.stderr,
@@ -191,6 +261,39 @@ function formatDisplayVersion(version: string): string {
   return version.startsWith('v') ? version : `v${version}`;
 }
 
+function nowIso(): string {
+  return new Date().toISOString();
+}
+
+/**
+ * Refuse the foreground install because another install is already in
+ * flight. The active-record case names the version being installed; the
+ * lock-held case cannot know it, so the message stays generic.
+ */
+function refuseForegroundInstall(
+  deps: UpgradeDeps,
+  currentVersion: string,
+  target: UpdateTarget,
+  source: InstallSource,
+  activeVersion: string | undefined,
+): number {
+  trackUpgradeEvent(deps.track, 'upgrade_command_failed', {
+    current_version: currentVersion,
+    target_version: target.version,
+    source,
+    stage: 'install',
+    reason: 'another update install is already in progress',
+  });
+  const suffix = activeVersion === undefined
+    ? ''
+    : ` (${formatDisplayVersion(activeVersion)})`;
+  deps.stderr.write(
+    `error: another update install is already in progress${suffix}; ` +
+      'try again once it finishes.\n',
+  );
+  return 1;
+}
+
 function formatErrorMessage(error: unknown): string {
   return error instanceof Error ? error.message : String(error);
 }
 
@@ -1,7 +1,7 @@
-import { valid } from 'semver';
+import { lt, valid } from 'semver';
 import { z } from 'zod';
 
-import { PYTHINKER_CODE_CDN_LATEST_JSON_URL, PYTHINKER_CODE_CDN_LATEST_URL } from '#/constant/app';
+import { PYTHINKER_CODE_CDN_LATEST_JSON_URL } from '#/constant/app';
 
 import type { UpdateManifest } from './types';
 
@@ -12,27 +12,59 @@ const RolloutBatchSchema = z.object({
   delaySeconds: z.number().int().min(0),
 });
 
+const UpdateManifestPlatformSchema = z.object({
+  url: z
+    .string()
+    .refine(
+      (value) => {
+        try {
+          const url = new URL(value);
+          return url.protocol === 'http:' || url.protocol === 'https:';
+        } catch {
+          return false;
+        }
+      },
+      { error: 'invalid url' },
+    ),
+  sha256: z.string().regex(/^[a-f0-9]{64}$/u),
+});
+
 /**
  * CDN `latest.json` wire format. Deliberately NOT `.strict()` — unknown
  * fields are ignored so future manifest additions never break shipped
- * clients (the plain-text `/latest` taught us that hard-failing on
- * unexpected content bricks the update path forever).
+ * clients. Hard-failing on unexpected content bricks the update path for
+ * every already-installed client, which is unrecoverable from our side.
  */
 export const UpdateManifestSchema = z.object({
   version: z.string().refine((value) => valid(value) !== null, { error: 'invalid semver' }),
   publishedAt: z
     .string()
     .refine((value) => Number.isFinite(Date.parse(value)), { error: 'invalid timestamp' }),
   rollout: z.array(RolloutBatchSchema).readonly().default([]),
+  /**
+   * Resolved per-platform artifacts, keyed `<platform>-<arch>`. A malformed
+   * value drops only this field via `.catch(undefined)` so `version` and
+   * `publishedAt` still parse — failing the whole manifest would cost the
+   * client its update over one unreadable field.
+   */
+  platforms: z
+    .record(z.string(), UpdateManifestPlatformSchema)
+    .readonly()
+    .optional()
+    .catch(undefined),
+  /**
+   * Lowest version that can still work against the current services. A
+   * malformed value drops only this field via `.catch(undefined)` so
+   * `version` and `publishedAt` still parse — a client below the floor must
+   * not lose its update because the declaration is unreadable.
+   */
+  minRequiredVersion: z
+    .string()
+    .refine((value) => valid(value) !== null, { error: 'invalid semver' })
+    .optional()
+    .catch(undefined),
 });
 
-export interface FetchLatestResult {
-  /** Raw newest version — what `pythinker upgrade` installs, never rollout-gated. */
-  readonly latest: string;
-  /** Null when the JSON manifest was unavailable and we fell back to plain text. */
-  readonly manifest: UpdateManifest | null;
-}
-
 async function fetchWithTimeout(fetchImpl: typeof fetch, input: string): Promise<Response> {
   const controller = new AbortController();
   const timeout = setTimeout(() => {
@@ -46,52 +78,68 @@ async function fetchWithTimeout(fetchImpl: typeof fetch, input: string): Promise
 }
 
 /**
- * Fetch the latest published Pythinker Code version from the CDN.
+ * Fetch the CDN update manifest — the client's only source of update truth.
  *
- * **Throws** on any failure (network error, non-2xx, empty body, non-semver
- * text). Callers must catch — `refreshUpdateCache` deliberately lets the
- * error propagate so the existing cache stays intact instead of being
- * overwritten with a null `latest` on a transient blip.
+ * **Throws** on any failure (network error, non-2xx, unparseable body). Callers
+ * must catch: `refreshUpdateCache` deliberately lets the error propagate so the
+ * existing cache stays intact instead of being overwritten on a transient blip.
+ *
+ * There is deliberately no fallback to the plain-text `/latest` endpoint, which
+ * still exists for `install.sh`. That endpoint carries no per-platform artifact
+ * data, so falling back to it turns "cannot verify this platform has a build"
+ * into "verified" and re-opens the hole `platforms` exists to close. It also
+ * cannot fail independently: both files come from the same generator in the same
+ * deploy, and the manifest schema already tolerates unknown fields and a
+ * malformed `platforms` value without failing the parse.
  *
  * `fetchImpl` is injectable for tests; defaults to the global `fetch`.
  */
-export async function fetchLatestVersionFromCdn(
+export async function fetchUpdateManifest(
   fetchImpl: typeof fetch = fetch,
-): Promise<string> {
-  const response = await fetchWithTimeout(fetchImpl, PYTHINKER_CODE_CDN_LATEST_URL);
-  if (!response.ok) {
-    throw new Error(`CDN /latest returned HTTP ${response.status}`);
-  }
-  const raw = (await response.text()).trim();
-  if (valid(raw) === null) {
-    throw new Error(`CDN /latest returned invalid semver: ${JSON.stringify(raw)}`);
-  }
-  return raw;
-}
-
-async function fetchUpdateManifestFromCdn(fetchImpl: typeof fetch): Promise<UpdateManifest> {
+): Promise<UpdateManifest> {
   const response = await fetchWithTimeout(fetchImpl, PYTHINKER_CODE_CDN_LATEST_JSON_URL);
   if (!response.ok) {
     throw new Error(`CDN /latest.json returned HTTP ${response.status}`);
   }
   return UpdateManifestSchema.parse(JSON.parse(await response.text()));
 }
 
+export type ArtifactAvailability = 'available' | 'unavailable';
+
 /**
- * Fetch the rollout manifest, falling back to the plain-text `/latest` when
- * `latest.json` is unavailable or malformed. The fallback removes any
- * deployment-order coupling between client releases and the CDN file, and a
- * null manifest means "fully rolled out" — exactly the pre-rollout behavior.
- *
- * **Throws** only when both sources fail; callers must catch (see above).
+ * Whether the manifest advertises an artifact for `target`. Unknown — a
+ * null manifest or one that predates artifact addressing — resolves to
+ * 'available': a CDN blip must never stop a working update, while a
+ * manifest that explicitly omits the target platform is a definitive
+ * denial.
  */
-export async function fetchLatestFromCdn(
-  fetchImpl: typeof fetch = fetch,
-): Promise<FetchLatestResult> {
-  const manifest = await fetchUpdateManifestFromCdn(fetchImpl).catch(() => null);
-  if (manifest !== null) {
-    return { latest: manifest.version, manifest };
+export function manifestArtifactAvailability(
+  manifest: UpdateManifest | null,
+  target: string = `${process.platform}-${process.arch}`,
+): ArtifactAvailability {
+  if (manifest === null) {
+    return 'available';
+  }
+  if (manifest.platforms === undefined) {
+    return 'available';
   }
-  const latest = await fetchLatestVersionFromCdn(fetchImpl);
-  return { latest, manifest: null };
+  return Object.hasOwn(manifest.platforms, target) ? 'available' : 'unavailable';
+}
+
+/**
+ * Whether the running version is below the manifest's declared floor, which
+ * makes its update mandatory rather than merely available: the staged rollout
+ * delay exists for ordinary releases, not for one a client cannot skip.
+ *
+ * An absent, unreadable or non-semver floor answers false — a declaration we
+ * cannot understand must not escalate an update on its own.
+ */
+export function isBelowMinRequiredVersion(
+  manifest: UpdateManifest | null,
+  currentVersion: string,
+): boolean {
+  const floor = manifest?.minRequiredVersion;
+  if (floor === undefined) return false;
+  if (valid(currentVersion) === null || valid(floor) === null) return false;
+  return lt(currentVersion, floor);
 }
-Original file line number
+Diff line change
@@ @@ -0,0 +1,5 @@ @@
 +---
 +"@pythoughts/pythinker-code": patch
 +---
++
 +Stop offering an update with no build for the running platform, give every installer network call a timeout, expire a stale install lease instead of blocking updates forever, and say which version is installing and why a failed one stopped retrying.