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FluffBuzz builds a custom system prompt for every agent run. The prompt is FluffBuzz-owned and does not use the pi-coding-agent default prompt. The prompt is assembled by FluffBuzz and injected into each agent run. Provider plugins can contribute cache-aware prompt guidance without replacing the full FluffBuzz-owned prompt. The provider runtime can:
  • replace a small set of named core sections (interaction_style, tool_call_style, execution_bias)
  • inject a stable prefix above the prompt cache boundary
  • inject a dynamic suffix below the prompt cache boundary
Use provider-owned contributions for model-family-specific tuning. Keep legacy before_prompt_build prompt mutation for compatibility or truly global prompt changes, not normal provider behavior. The OpenAI GPT-5 family overlay keeps the core execution rule small and adds model-specific guidance for persona latching, concise output, tool discipline, parallel lookup, deliverable coverage, verification, missing context, and terminal-tool hygiene.

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Structure

The prompt is intentionally compact and uses fixed sections:
  • Tooling: structured-tool source-of-truth reminder plus runtime tool-use guidance.
  • Execution Bias: compact follow-through guidance: act in-turn on actionable requests, continue until done or blocked, recover from weak tool results, check mutable state live, and verify before finalizing.
  • Safety: short guardrail reminder to avoid power-seeking behavior or bypassing oversight.
  • Skills (when available): tells the model how to load skill instructions on demand.
  • FluffBuzz Self-Update: how to inspect config safely with config.schema.lookup, patch config with config.patch, replace the full config with config.apply, and run update.run only on explicit user request. The owner-only gateway tool also refuses to rewrite tools.exec.ask / tools.exec.security, including legacy tools.bash.* aliases that normalize to those protected exec paths.
  • Workspace: working directory (agents.defaults.workspace).
  • Documentation: local path to FluffBuzz docs (repo or npm package) and when to read them.
  • Workspace Files (injected): indicates bootstrap files are included below.
  • Sandbox (when enabled): indicates sandboxed runtime, sandbox paths, and whether elevated exec is available.
  • Current Date & Time: user-local time, timezone, and time format.
  • Reply Tags: optional reply tag syntax for supported providers.
  • Heartbeats: heartbeat prompt and ack behavior, when heartbeats are enabled for the default agent.
  • Runtime: host, OS, node, model, repo root (when detected), thinking level (one line).
  • Reasoning: current visibility level + /reasoning toggle hint.
The Tooling section also includes runtime guidance for long-running work:
  • use cron for future follow-up (check back later, reminders, recurring work) instead of exec sleep loops, yieldMs delay tricks, or repeated process polling
  • use exec / process only for commands that start now and continue running in the background
  • when automatic completion wake is enabled, start the command once and rely on the push-based wake path when it emits output or fails
  • use process for logs, status, input, or intervention when you need to inspect a running command
  • if the task is larger, prefer sessions_spawn; sub-agent completion is push-based and auto-announces back to the requester
  • do not poll subagents list / sessions_list in a loop just to wait for completion
When the experimental update_plan tool is enabled, Tooling also tells the model to use it only for non-trivial multi-step work, keep exactly one in_progress step, and avoid repeating the whole plan after each update. Safety guardrails in the system prompt are advisory. They guide model behavior but do not enforce policy. Use tool policy, exec approvals, sandboxing, and channel allowlists for hard enforcement; operators can disable these by design. On channels with native approval cards/buttons, the runtime prompt now tells the agent to rely on that native approval UI first. It should only include a manual /approve command when the tool result says chat approvals are unavailable or manual approval is the only path.

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Prompt modes

FluffBuzz can render smaller system prompts for sub-agents. The runtime sets a promptMode for each run (not a user-facing config):
  • full (default): includes all sections above.
  • minimal: used for sub-agents; omits Skills, Memory Recall, FluffBuzz Self-Update, Model Aliases, User Identity, Reply Tags, Messaging, Silent Replies, and Heartbeats. Tooling, Safety, Workspace, Sandbox, Current Date & Time (when known), Runtime, and injected context stay available.
  • none: returns only the base identity line.
When promptMode=minimal, extra injected prompts are labeled Subagent Context instead of Group Chat Context.

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Workspace bootstrap injection

Bootstrap files are trimmed and appended under Project Context so the model sees identity and profile context without needing explicit reads:
  • AGENTS.md
  • SOUL.md
  • TOOLS.md
  • IDENTITY.md
  • USER.md
  • HEARTBEAT.md
  • BOOTSTRAP.md (only on brand-new workspaces)
  • MEMORY.md when present
All of these files are injected into the context window on every turn unless a file-specific gate applies. HEARTBEAT.md is omitted on normal runs when heartbeats are disabled for the default agent or agents.defaults.heartbeat.includeSystemPromptSection is false. Keep injected files concise — especially MEMORY.md, which can grow over time and lead to unexpectedly high context usage and more frequent compaction.
Note: memory/*.md daily files are not part of the normal bootstrap Project Context. On ordinary turns they are accessed on demand via the memory_search and memory_get tools, so they do not count against the context window unless the model explicitly reads them. Bare /new and /reset turns are the exception: the runtime can prepend recent daily memory as a one-shot startup-context block for that first turn.
Large files are truncated with a marker. The max per-file size is controlled by agents.defaults.bootstrapMaxChars (default: 12000). Total injected bootstrap content across files is capped by agents.defaults.bootstrapTotalMaxChars (default: 60000). Missing files inject a short missing-file marker. When truncation occurs, FluffBuzz can inject a warning block in Project Context; control this with agents.defaults.bootstrapPromptTruncationWarning (off, once, always; default: once). Sub-agent sessions only inject AGENTS.md and TOOLS.md (other bootstrap files are filtered out to keep the sub-agent context small). Internal hooks can intercept this step via agent:bootstrap to mutate or replace the injected bootstrap files (for example swapping SOUL.md for an alternate persona). If you want to make the agent sound less generic, start with SOUL.md Personality Guide. To inspect how much each injected file contributes (raw vs injected, truncation, plus tool schema overhead), use /context list or /context detail. See Context.

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Time handling

The system prompt includes a dedicated Current Date & Time section when the user timezone is known. To keep the prompt cache-stable, it now only includes the time zone (no dynamic clock or time format). Use session_status when the agent needs the current time; the status card includes a timestamp line. The same tool can optionally set a per-session model override (model=default clears it). Configure with:
  • agents.defaults.userTimezone
  • agents.defaults.timeFormat (auto | 12 | 24)
See Date & Time for full behavior details.

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Skills

When eligible skills exist, FluffBuzz injects a compact available skills list (formatSkillsForPrompt) that includes the file path for each skill. The prompt instructs the model to use read to load the SKILL.md at the listed location (workspace, managed, or bundled). If no skills are eligible, the Skills section is omitted. Eligibility includes skill metadata gates, runtime environment/config checks, and the effective agent skill allowlist when agents.defaults.skills or agents.list[].skills is configured. 
<available_skills>
  <skill>
    <name>...</name>
    <description>...</description>
    <location>...</location>
  </skill>
</available_skills>
This keeps the base prompt small while still enabling targeted skill usage. The skills list budget is owned by the skills subsystem:
  • Global default: skills.limits.maxSkillsPromptChars
  • Per-agent override: agents.list[].skillsLimits.maxSkillsPromptChars
Generic bounded runtime excerpts use a different surface:
  • agents.defaults.contextLimits.*
  • agents.list[].contextLimits.*
That split keeps skills sizing separate from runtime read/injection sizing such as memory_get, live tool results, and post-compaction AGENTS.md refreshes.

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Documentation

When available, the system prompt includes a Documentation section that points to the local FluffBuzz docs directory (either docs/ in the repo workspace or the bundled npm package docs) and also notes the public mirror, source repo, community Discord, and ClawHub (https://buzzhub.ai) for skills discovery. The prompt instructs the model to consult local docs first for FluffBuzz behavior, commands, configuration, or architecture, and to run fluffbuzz status itself when possible (asking the user only when it lacks access).