v0.1.5-alpha.2 and rc.1: The 0.1.5 Series Enters Candidate Stage

v0.1.5-alpha.1: A Skipped Number, an Experimental Sidebar, and Session Format V3 covered how the series opened one day after v0.1.3-alpha.2, skipping the 0.1.4 number entirely. Two further releases quickly followed: v0.1.5-alpha.2 published 2026-09-09 at 14:23 UTC, and v0.1.5-rc.1 landed 2026-09-10 at 03:09 UTC — under 13 hours later. With rc.1, the series carries its first release candidate, and the notes state its scope explicitly: the release summarizes the major user- and developer-facing changes since v0.1.2-rc.1.

alpha.2: Sidebar previews and model-delivered files

alpha.2 extends the Sidebar that alpha.1 introduced: it now previews common document types, including Markdown, syntax-highlighted code, HTML, PDF, and images. Models can explicitly deliver files in a conversation, and delivered files open as a Sidebar preview, in the default application, or in the file manager. The /feedback command accepts detailed submissions. The release’s fixes cover pi-ai model settings that a catalog change had invalidated, validation of custom-provider Base URLs before model discovery, the Windows folder picker opening behind other windows, a composer placeholder that survived whitespace input, guidance that reached subagents whose tools had been filtered away, and repeated MCP pagination cursors that could hang startup.

rc.1’s headline: a new default DeepSeek model

The rc.1 notes lead with a model change: the DeepSeek adapter adds DeepSeek-V41-Flash (deepseek-flash), which supports text, image, and in-history system prompt updates. New sessions use it by default; when the configuration file explicitly specifies a model, that configured value takes precedence. The same notes carry the dynamic system prompt feature alpha.1 introduced — system prompts update without invalidating the KV Cache when the configured model explicitly declares support.

Around the new model, rc.1 widens the input and network surface: Web accepts uploads of arbitrary file types, with files and images sharing a preview area and background uploads exposing progress, cancellation, and persistence across conversation switches; all outbound network requests honor HTTP_PROXY, HTTPS_PROXY, ALL_PROXY, and NO_PROXY from the startup environment; model discovery reads models objects from custom providers and native Anthropic model lists, filling in model names, context windows, and maximum output tokens; and a new “Open in” control in the Web header opens the Workspace in an installed editor, IDE, terminal, or file manager.

Continuable subagents gain message queueing, editing, deletion, Steer for individual or all queued messages, and Stop; a queued submission shows a Sending state and cannot be edited, deleted, or steered until delivery completes. Feedback can be submitted without continuing the conversation. Long conversations open, resume, and continue with less lag and lower memory usage, and when a referenced conversation is longer than its preview, the model can read the omitted content on demand.

The developer-facing layer

The Chores section carries the changes integrators need to act on:

• Session lifecycle. Session persistence moves to lifecycle-scoped SessionHandles, agentLoop.create() becomes asynchronous, and a new session lock ensures each session is held by at most one process.
• Default tools. SDK, Headless, and ACP use read, write, and edit for file editing by default; Web minimal and Python sdk-minimal provide only a persistent shell unless str_replace_editor is explicitly enabled.
• Persona configuration. Custom persona configuration splits into a prefix and a suffix; existing configurations and related constants need updating.
• Web plugin panels. Plugins register global panels through sidebar.panellist and main; the former conversation slot moves to the conversation key under main.
• Agent Teams. The experimental Agent Teams packages install from npm, but only after a user explicitly adds the profile — they are not enabled by default.

Smaller Chores items: subprocess cleanup improves on Windows and supported Linux environments, and ordinary subprocess handles no longer expose the pid; unobserved file writes and failed edits report a standardized FS_NOT_OBSERVED diagnostic; the Python SDK ships a macOS x64 runtime wheel for Intel Macs; pi-ai moves to 0.85.1; and session format V3 — covered when alpha.1 shipped — remains the migration custom log readers must adapt to.

Fixes in the cumulative candidate

Among the fixes rc.1’s notes list: pausing a goal in Web immediately aborts the active model turn, and only the user can resume it; DeepSeek streaming tool-call continuation chunks preserve tool-call IDs and names instead of overwriting them with empty values and producing records that cannot be reopened; the Python SDK single-file runtime stops rewriting Bash commands that begin with node; a conversation selected from search opens in its Workspace instead of leaving the search interface up; Windows drive-root Workspaces validate paths correctly; Web reconnects automatically after a disconnection; and chat scrolls to the bottom again after sending a message or resizing the window.

Channel status

The releases API lists every release published on the channel so far as prerelease-flagged, rc.1 included — no stable build exists. Live repo metadata stays in the site’s build-time snapshot and stats page; this article cites no point-in-time star counts.