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thndrs

Prompt Assembly

Prompt Bundle

Section titled “Prompt Bundle”

thndrs builds a structured PromptBundle before converting it to provider messages. This keeps prompt construction inspectable and avoids ad hoc string concatenation.

The rendered prompt uses XML-shaped sections for scanability. See Prompt XML Syntax for the tag and CDATA conventions.

Base Identity

Section titled “Base Identity”

The base identity describes thndrs as a concise terminal coding assistant built in Rust.

Harness Policy

Section titled “Harness Policy”

The harness policy describes the bounded tool boundary, workspace containment, and the absence of raw shell access.

Environment Metadata

Section titled “Environment Metadata”

Environment metadata includes workspace root, rounded current date/timezone, selected model, and search mode.

Self-Knowledge Snapshot

Section titled “Self-Knowledge Snapshot”

The generated thndrs_self_knowledge block describes the current harness run in a compact, model-visible form. It includes:

  • app version and broad capabilities
  • runtime state: workspace, renderer mode, provider, model, search mode, search backend details, URL-reading behavior, and tool names
  • major capabilities
  • references: local documentation entry points and available skill names and locations
  • prompt context like prompt fragment names and loaded project-context metadata
  • visible diagnostics

This block is metadata only. It does not include full prompt fragment text, AGENTS.md contents, user prompt text, or provider-private state.

Project Context

Section titled “Project Context”

Project context includes loaded AGENTS.md metadata and text when included. Metadata includes path, scope, content hash, and truncation state.

AGENTS.md is treated as repository guidance, not executable configuration. It can describe conventions, commands to consider, and project caveats, but it cannot grant permissions, reveal secrets, change provider/model settings, bypass tests, disable safety checks, or override direct user/system/developer instructions.

Instruction precedence is:

  1. Harness safety policy.
  2. Current user prompt.
  3. CLI choices owned by the user.
  4. Applicable AGENTS.md guidance.
  5. Built-in defaults.

The current implementation loads the root AGENTS.md from the selected workspace when present and marks truncation visibly.

Good AGENTS.md files are short and practical: project overview, relevant build/test commands, style conventions, testing expectations, safety gotchas, and monorepo navigation notes. Avoid long architecture essays, stale command lists, tool-specific prompts, conflicting instructions, and instructions to skip checks or ignore failures.

Tool Catalog

Section titled “Tool Catalog”

The tool catalog contains provider-native schemas for local tools. Text descriptions are intentionally minimal: name, purpose, safety limits, and truncation behavior.

Transcript Tail

Section titled “Transcript Tail”

The model-visible transcript tail includes relevant user, assistant, reasoning, and tool entries. UI-only status rows, live-only stream deltas, statusline metadata, and renderer artifacts are excluded.

User Turn

Section titled “User Turn”

The user turn is the current submitted prompt text. Attachments are deferred.

Section titled “Print Prompt”

--print-prompt prints the assembled prompt bundle and lowered messages with secrets redacted, then exits without calling the provider.

History Reuse

Section titled “History Reuse”

When history reuse is unavailable, thndrs includes the active size-capped AGENTS.md context and records hash/truncation metadata.