pi coding agent v0.86.0：破坏性变更与 Prompt Cache Warming

New Features

• Prompt cache warming — Keep valuable prompt caches alive during long tool runs and optionally while idle using cost-aware refreshes. See Cache Warming.
• Bug reporting — Report problems with /bug using redacted diagnostics, optional transcripts, or exported ZIP archives. See Reporting Bugs.
• Transcript-aware prompt and tool updates — Preserve instruction and tool changes across resume and branch navigation while retaining cached prefixes. See before_agent_start.
• Offline Radius model catalog — Select Radius models immediately, with cached and live catalogs overlaid when available. See Radius.
• Per-model compaction budgets — Configure reserved and recent-token budgets by model. See Per-model overrides.

Breaking Changes

• Changed inherited pi-ai provider stream inputs from Context to normalized TranscriptContext values. Custom providers must read system prompts and tool declarations from context.messages with getCurrentSystemPrompt() and getCurrentTools(). See Custom Streaming API.
• Restricted inherited ToolCall.arguments and ToolResultMessage.details to JSON-compatible values, changed ToolResultMessage into a conditional type, and made JsonValue arrays readonly.
• user_bash now fails closed: errors or invalid defined results abort the command without invoking later handlers or executing locally. Return undefined to continue propagation; otherwise return { operations } or { result } (#9068).

Added

• Added transcript-backed mid-conversation system prompt and tool changes so instruction and tool updates survive resume and branch navigation while preserving cached prefixes on supported models. See before_agent_start and Entry Types (#9548).
• Added inherited native deferred tool loading for Fireworks Messages models. Use ToolSearch or tool_search as the loader name for prompt-prefix deferral (#9323).
• Added click toggling for branch summaries, compaction summaries, and skill invocation entries.
• Added the public Radius model catalog for immediate and offline model selection, with cached and live gateway catalogs overlaid when available.
• Added ctx.modelRegistry.stream() and streamSimple() for extension model calls through configured providers with resolved authentication (#8964).
• Added per-model reserveTokens and keepRecentTokens settings through compaction.modelOverrides, with ordinary compaction settings as fallback (#8133).
• Added compat.allowedFallbackModels configuration for overriding or disabling Anthropic server-side fallback models (#9294).
• Added an unsubscribe function from pi.on() so extensions can drop event handlers. Handlers added or removed during a dispatch apply to later dispatches, not the current one (#8967).
• Exported extension hook event and result types that were previously omitted from the package entry points (#9642).
• Added /bug [description] to report a bug to the Pi developers. The report bundles environment, model, provider, extension, and settings metadata (secrets redacted), assistant message diagnostics from the session, optionally the session transcript, or a model-written summary of what went wrong instead. It is uploaded to Radius (no login required; attributed when logged in) or exported as a zip archive, and the report id is recorded in the session as a pi.bug-report entry. Crashes are recorded in ~/.pi/agent/crashes.json, announced once on the next start, and attached to the next report; unexplained errors and exhausted retries point at /bug once per session.
• Added cost-aware prompt-cache warming during long tool runs and optionally while idle, with configurable modes, model cache-lifetime metadata, /session diagnostics, transcript notices, and the cache_warming_decision extension event. See Cache Warming (#9668).

Changed

• Made --resume session results appear progressively, using file modification times to prioritize all-folder loading and cancelling outstanding transcript reads after selection.
• Reduced --continue startup time by checking candidate session headers in modification-time order and stopping after the newest matching session.
• Replaced the external native clipboard dependency with bundled asynchronous macOS, Windows, and X11 helpers while preserving platform command and OSC 52 fallbacks (#9163).
• Reduced inherited fuzzy search latency for long texts by using native substring search instead of scanning each character in JavaScript (#9267).
• Moved compaction, branch summarization, and retry spinners into the editor border alongside the working indicator. Custom editors use the same embedding opt-in for all status spinners.
• Enabled strict-prefer JSON-schema sampling by default for built-in read, bash, powershell, edit, and write tools, without requiring PI_EXPERIMENTAL. Extensions can re-register tool definitions with constrainedSampling: false.
• Formatted Bash and PowerShell tool durations of at least one minute as minutes and seconds, with hours when needed (#9628).
• Deferred the extension compiler and bundled virtual modules until a filesystem extension is loaded, reducing the baseline SDK import cost (#9540).

Fixed

• Fixed GitHub Copilot GPT models, including GPT-6 Astra, using the Chat Completions adapter instead of the required Responses adapter (#9253 by @petrroll).
• Fixed inherited DeepSeek V4.1 thinking levels on OpenRouter and OpenCode Go preserving provider effort metadata (#9485).
• Fixed inherited bodyless HTTP 400/413 errors from non-Cerebras providers being misclassified as context overflow (#9482).
• Fixed inherited Vercel AI Gateway replaying unsigned thinking as assistant text (#9676).
• Fixed inherited Google Generative AI and Vertex AI using unsupported thinking levels when reasoning is omitted or when model capabilities differ within a Gemini family (#9455).
• Fixed inherited Anthropic-compatible relays breaking signed thinking replay when they report a different response model, while preserving fallback pricing (#9188).
• Fixed inherited Amazon Bedrock one-hour cache writes being priced at the five-minute rate (#9457).
• Fixed inherited quadratic CPU usage when draining buffered EventStream events (#9055).
• Fixed inherited Mistral Medium reasoning requests to use reasoning_effort for all reasoning-capable mistral-medium-* model IDs instead of the unsupported prompt_mode (#8700).
• Fixed inherited OpenCode and OpenCode Go requests to send x-opencode-session from sessionId across all supported API adapters (#9326).
• Fixed inherited OpenAI Codex requests to send the model's Off reasoning effort instead of omitting it, while respecting unsupported Off mappings (#9191).
• Fixed inherited Fireworks unsigned thinking replay and reasoning effort selection using catalog metadata, with verified DeepSeek V4 and Qwen3.8 fallbacks and removal of redundant GLM 5.2 and Kimi K3 effort aliases (#9323).
• Fixed inherited OpenRouter requests to send x-session-id from sessionId for Chat Completions and Anthropic Messages models when prompt caching is enabled (#9102).
• Fixed the inherited DeepSeek catalog to advertise deepseek-flash for DeepSeek V4.1 Flash instead of retired Flash aliases, and refreshed DeepSeek pricing metadata (#9423).
• Fixed inherited Mistral-hosted GLM-5.2 reasoning requests to use reasoning_effort instead of the ignored prompt_mode (#9375).
• Fixed inherited OpenAI-compatible Responses errors to identify the actual provider instead of always labeling them as OpenAI errors (#9298).
• Fixed inherited Baseten requests to send session-affinity headers from sessionId for automatic prompt-cache routing (#9629).
• Fixed inherited retry classification for Cloudflare 520 responses (#9627).
• Fixed inherited retry classification for transient Azure peak-load capacity errors (#9669).
• Fixed session tree navigation racing with active compaction and replacing its progress UI (#9179 by @acmerfight).