splice: derive recent-problems from problem-card frontmatter — the KNOWLEDGE.md zombie lies to every session

[aarontrowbridge]

Important

Problem — Every session's system prompt derives "Your recent problems" from KNOWLEDGE.md in the vault — but that file is frozen by design (the distiller no longer writes it) and its lines now lie: it claims a problem was solved 20× while the problem card it links to records 29 solves. The distillate's source of truth is the problem cards' frontmatter (slug, platform, kind, target, status, best fidelity, solve count, last-seen) — maintained, versioned, provenance-clean — but the splice still reads the zombie index. Every future session boot inherits the stale numbers, and the distiller's own new data (the Aug 22+ sweep backlog) never reaches the prompt.
Approach — Derive the section from the problem cards directly: scan the personal vault's problem-card frontmatter, sort by last-seen (freshest first), cap at the same line budget the current index read uses, and render the same section format the prompt already consumes (name · platform · kind/target · status · best fidelity · solve count). Keep the reader-facing section format stable so no other consumer changes. The frozen file stays on disk untouched (it's referenced by git history and possibly other tooling); the splice just stops depending on it.
Scope — in: the context-splice module's recent-problems derivation + its unit test · out: the vault-query verb's folder list (separate slice), the distiller itself, any vault file changes.

Acceptance Criteria

• The spliced "recent problems" section is derived from problem-card frontmatter (sorted by last-seen, capped), NOT from KNOWLEDGE.md
• The rendered section remains format-compatible with the current prompt (a session test or fixture pins the format)
• With a fixture vault whose card says 29 solves, the spliced section reports 29 — the zombie-index lie is dead
• The frozen KNOWLEDGE.md file is no longer read anywhere in the product (grep clean)

Testing Decisions

Extend the existing context-splice test suite (the stack-state splice already has coverage patterns to mirror); fixture vault with known frontmatter.

Prior Art

The memory-index splice (the MEMORY.md read pattern) and the problem-card frontmatter contract (the distiller's own schema, documented in the distiller spec).

Notes

Slice zero of the approved Armonia knowledge-system design (plans/2026-08-30-armonia-knowledge-system.md in the skill-health campaign, session-20260830-skill-health). The zombie-index phenomenon was verified on disk 2026-08-30. Part of the skill-health campaign.