The store engine moves into the client, and Python goes with it

Reading the catalog, choosing the release that fits this machine, unpacking it,
writing the menu entry and remembering what went where all happen in process now.
There is no interpreter to find, no child process, and no JSON-lines protocol
between the two halves — `PythonEngineProcessRunner`, the runtime locator, the two
engine mappers and the version negotiation are all gone, and with them the one
unchecked cast this codebase had (engine stdout to a typed event).

What that buys a person: on Windows and on a fresh Mac the app simply works. It
used to look for `python3`, `python` and `py -3` and draw a link to python.org
where none answered.

What lands on disk is unchanged, deliberately. `config.json` and `state.json` keep
the shell engine's snake_case shape, its `<scope>:<name>` keys and its file modes,
so a machine whose library was installed by the CLI keeps it — verified against the
Python engine on the same catalog: the same 13-title listing with zero field
differences, byte-identical payloads, identical modes and an identical Info.plist,
and a re-sync over a Python-installed home that writes nothing. Remove, prune,
prune-suppression on a named sync and the v1 state migration were each exercised.

Three things worth knowing about the new code:

  - the zip reader is ~150 lines over `node:zlib`, because Node has none and this
    application has no runtime dependencies. It restores the executable bit from
    each entry's external attributes, without which nothing installed can start,
    and it refuses zip64, unknown compression and paths that escape the
    destination rather than guessing;

  - `SUPPORTED_WARP_ENGINE_VERSIONS` names the engine versions this client is
    written against, checked against the `WarpEngine-Version` header every
    response carries. `selectCatalogDialect` switches over that list exhaustively,
    so adding a version fails the build — type checker and linter both — until
    somebody says what its catalog reads like. An absent header is read as the
    oldest version, which is what an engine before 0.4.0 is;

  - refresh and the language picker are icons at the foot of the side menu now,
    both named for a tooltip and a screen reader, the picker still a real
    `<select>` under its glyph.

The repository is free of Python as well: the Makefile, the CI check and the
release script read package.json and the forge's JSON with Node.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>

src/infrastructure/http/StoreHttpClient.ts

@@ -0,0 +1,130 @@
+import fs from 'node:fs'
+import http from 'node:http'
+import https from 'node:https'
+import path from 'node:path'
+import { pipeline } from 'node:stream/promises'
+import { HttpStatusError } from './HttpTextClient'
+
+const MAX_REDIRECTS = 5
+
+export interface HttpResponseBody {
+  readonly body: Buffer
+  readonly contentType: string
+  /** Lower-cased names, as Node delivers them. The engine version arrives in one. */
+  readonly headers: Readonly<Record<string, string>>
+}
+
+export interface StoreHttpOptions {
+  readonly userAgent: string
+  /** Seconds, as the store config states it. */
+  readonly timeout: number
+  readonly insecure: boolean
+}
+
+/**
+ * The store's own HTTP: bytes rather than text, and a streaming download.
+ *
+ * Separate from `HttpTextClient` because the two have different jobs — that one
+ * fetches a config file and wants a string, this one fetches a catalog and a
+ * multi-megabyte archive and must not hold the archive in memory. It also honours
+ * the store config's `timeout` and `insecure`, which are per-store settings rather
+ * than properties of this application.
+ */
+export class StoreHttpClient {
+  public constructor (private readonly options: StoreHttpOptions) {}
+
+  public async readBytes (url: string): Promise<HttpResponseBody> {
+    return await this.request(url, MAX_REDIRECTS, async (
+      response: http.IncomingMessage
+    ): Promise<HttpResponseBody> => {
+      const chunks: Buffer[] = []
+      for await (const chunk of response) chunks.push(Buffer.from(chunk as Buffer))
+      return {
+        body: Buffer.concat(chunks),
+        contentType: response.headers['content-type'] ?? '',
+        headers: readHeaders(response)
+      }
+    })
+  }
+
+  /**
+   * Stream `url` into `destination` atomically. Returns bytes written.
+   *
+   * A part file next to the target, then a rename: a download interrupted halfway
+   * must not look like a complete archive to the next sync.
+   */
+  public async download (url: string, destination: string): Promise<number> {
+    const directory = path.dirname(destination)
+    fs.mkdirSync(directory, { recursive: true })
+    const partial = `${destination}.part`
+    let written = 0
+
+    try {
+      await this.request(url, MAX_REDIRECTS, async (response: http.IncomingMessage): Promise<void> => {
+        response.on('data', (chunk: Buffer): void => { written += chunk.length })
+        await pipeline(response, fs.createWriteStream(partial))
+      })
+      if (written === 0) throw new Error(`${url} returned an empty response`)
+      fs.renameSync(partial, destination)
+    } catch (error: unknown) {
+      fs.rmSync(partial, { force: true })
+      throw error
+    }
+    return written
+  }
+
+  private async request<TResult> (
+    url: string,
+    redirectsLeft: number,
+    consume: (response: http.IncomingMessage) => Promise<TResult>
+  ): Promise<TResult> {
+    const response = await this.open(url)
+    const status = response.statusCode ?? 0
+    const location = response.headers.location
+
+    if (status >= 300 && status < 400 && location !== undefined) {
+      response.resume()
+      if (redirectsLeft <= 0) throw new Error(`too many redirects for ${url}`)
+      return await this.request(new URL(location, url).toString(), redirectsLeft - 1, consume)
+    }
+    if (status !== 200) {
+      response.resume()
+      throw new HttpStatusError(url, status)
+    }
+    return await consume(response)
+  }
+
+  private async open (url: string): Promise<http.IncomingMessage> {
+    return new Promise<http.IncomingMessage>((
+      resolve: (response: http.IncomingMessage) => void,
+      reject: (error: Error) => void
+    ): void => {
+      const secure = !url.startsWith('http://')
+      const client = secure ? https : http
+      const request = client.get(url, {
+        headers: { 'User-Agent': this.options.userAgent },
+        ...(secure && this.options.insecure ? { rejectUnauthorized: false } : {})
+      }, resolve)
+
+      request.setTimeout(Math.max(1, this.options.timeout) * 1000, (): void => {
+        request.destroy(new Error(`${url} timed out`))
+      })
+      request.on('error', reject)
+    })
+  }
+}
+
+/**
+ * The response headers as plain strings.
+ *
+ * Node gives a repeated header as an array; the ones this client reads are single-valued,
+ * and joining is a truer answer than picking the first.
+ */
+function readHeaders (response: http.IncomingMessage): Readonly<Record<string, string>> {
+  const headers: Record<string, string> = {}
+  for (const [name, value] of Object.entries(response.headers)) {
+    if (value === undefined) continue
+    headers[name.toLowerCase()] = Array.isArray(value) ? value.join(', ') : value
+  }
+  return headers
+}