[v0.8 Prompts P01] preserve typed system-prompt provenance

[sethkarten]

P01 — typed system-prompt provenance

Published main-based head: 1a53c7064c8689f39c56da4639be7df1738fbc8e
Base: main; authoritative integrated main parent 47dccfad4c0e71cd357f12d233ac44cc803af8c5.
Ordered parents: prior corrected P01 4043f6b2418c636b0d27844af1f34ae0919bc1e3, then main 47dccfad4c0e71cd357f12d233ac44cc803af8c5.
Incremental scope: exactly nine P01 paths; corrected P01 semantic patch only, with all main-only content preserved.

P01 distinguishes built-in, custom (including present-empty), and unknown prompt provenance; unknown fails closed. Root, rebuild, runtime replacement, and actual child routes are covered. The prior depth-test defect was corrected append-only. Independent Terra review accepted the final main-based tree; neutral focused validation passes 94/94 and root type-check passes.

P02 is the separate child PR #1237 based on v080/prompts and must merge after P01.

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Note

Preserve typed system prompt provenance through session and resource loader assembly

• Introduces a SystemPromptSource discriminated union (built_in, custom, unknown) in system-prompt.ts to carry authoritative provenance and content through prompt assembly.
• DefaultResourceLoader in resource-loader.ts gains a getSystemPromptSource() method and tracks provenance when resolving system prompts, including a systemPromptSourceOverride option with malformed-input diagnostics.
• buildSystemPrompt now routes on provenance: custom preserves content verbatim (plus context/guidelines appendages), built_in uses default RLM assembly, and unknown returns an empty string.
• AgentSession in agent-session.ts replaces getSystemPrompt() with a source-aware flow, passing systemPromptSource downstream instead of customPrompt.
• New control-loop and clear-direct-prose guidance blocks are prepended to all default-built RLM prompts in rlm.ts, and IPython guidance gains explicit anti-polling language.
• Risk: unknown provenance now yields an empty system prompt rather than falling back to built-in defaults, which is a failure-closed behavior change for malformed overrides.

^{Macroscope summarized 1a53c70.}

[sethkarten]

v0.8 stack checkpoint — 2026-08-11 15:50 UTC

This draft PR remains the GitHub Prompts stack surface and will be kept current.

• Parent Core candidate: 41ef592f8474a1d67b25ee6e495df24be3ab804e (feat(coding-agent): finalize v0.8 Core lifecycle and project MCP hardening #1224), exact CI green.
• Latest independently reviewed local prompt candidate: 839e06651165255e4802215c69ff7a5a49e082b0 (nine exact prompt/test paths).
• Active next step: semantic reconstruction of that reviewed tree onto Core 41ef, full prompt/resource/system tests, typecheck, nonwriting Biome, fresh review, then append-only/non-force advancement of this PR branch.

The current remote tip is historical until that verified successor lands; this is not a readiness claim.

[macroscopeapp]

Macroscope has since reviewed this pull request. An earlier review was skipped by a cost limit; a review has now completed, so that notice no longer applies.