Tianyi Cui
e6fad266a6
Define the in-file RFC contract in docs/rfc/README.md § The file format: the header block (`# RFC: <title>` plus a dateless Status enum cross-checked against the lifecycle folder), the per-lifecycle body skeleton (a Problem opener everywhere; Proposal/Alternatives considered/ Acceptance criteria/Risks in proposed/; present-tense Decision/ Consequences with proposal-era headings banned in implemented/; the frozen proposal shape in rejected/), and a mandatory Alternatives considered section with a date-fenced grandfather comment for pre-format RFCs whose alternatives are not reconstructible from the record. Enforce it with a new doc-sync gate, scripts/verify-rfc-format.ts, and normalize all 112 RFCs to it: ~15 Status-line spellings collapse to the enum, 29 Context openers become Problem, the 39 legacy-format XXX debt markers are resolved and banned from reappearing, proposal-era sections in implemented RFCs are rewritten to shipped reality (including the web/fs/subagent seam RFCs' migration plans and test checklists, closing the doc-tiers deferred-work item on the web seam), every RFC gains an Alternatives considered section or the grandfather comment, and the bilingual pair is re-mirrored and re-recorded. Move the generated index tables out of README.md into a fully generated docs/rfc/INDEX.md — gen-rfc-index now writes the whole file, and verify-rfc-classification checks its freshness and rejects index-shaped rows in the curated README — which makes room for the format contract to live in the README front door instead of a separate FORMAT.md. The decision record, and the first RFC written in the new format, is docs/rfc/implemented/process/2026-07-05-uniform-rfc-format.md.
4.1 KiB
RFC: Drop the image content block until a path can honor it
Status: implemented
Problem
ImageBlock (packages/llm/llm/src/types.ts) had no production producer, and every consumer on every path DROPPED it: the deepseek adapter's serializer skipped image blocks (a documented MVP limitation), the pi-ai converter skipped them as unrepresentable, the ACP codec neither advertises image prompt capability nor forwarded image blocks outbound and REJECTS image prompt content inbound, and the compaction estimator charged a flat token constant and rendered [image]. An ImageBlock constructed then would silently vanish from the wire — the vocabulary advertised a capability no path honored, which is the silent-data-loss shape AGENTS.md's defensive patterns warn against. The only constructors anywhere were tests pinning the skip/drop/estimate branches.
Decision
Remove ImageBlock, its ContentBlockMap entry (and its cache?: CacheHint field with it), the explicit image estimate/placeholder arms in compact-basic, and the image-naming comments in the deepseek serializer's, pi-ai converter's, and ACP codec's default arms — those default arms absorb the case the way they absorb any unknown block type. Updated in the same change: the vocabulary line in architecture.md, the block list in packages/llm/llm/README.md, the deepseek README's image-skip row, the pi-ai README's images-not-representable row, the compact-basic README's image-estimation and [image]-placeholder rows, the pastes in core.md and llm-streaming.md, and the content-block vocabulary RFC's block list and multimodal-home consequence per implemented/AGENTS.md; the tests that constructed image blocks to exercise the removed branches were dropped (the estimate pin) or retargeted onto the merge-extensible default arms (plugin-added block types). The ACP codec's inbound rejection of image PROMPT content is unaffected — that guard is about protocol content a client can send regardless of our vocabulary, and it stays.
Alternatives considered
Why not keep it?
This was the most contested cut in the batch. Multimodal input (screenshots) is a plausible near-term coding-agent feature, and the content-block vocabulary RFC reserved the slot deliberately. Two responses. First, ContentBlockMap is merge-extensible by design: a real multimodal feature reintroduces image in core in the same coordinated change that maps it in the adapters, advertises and renders it in ACP, and prices it in compaction — the producer and its consumers arrive together, which is how the map is meant to grow. Second, the middle option — keep the type but make adapters throw UNSUPPORTED instead of silently dropping — converts this into exactly the shape the sibling request-knobs proposal (2026-07-04-drop-inert-request-knobs) argues against: surface whose only implementation is rejection. Absence (a compile error at the would-be producer) is strictly clearer than either silent loss or universal throw.
The recorded fallback, had review landed on keeping the slot: keep ImageBlock but replace every silent skip with a loud rejection, and document that policy in the vocabulary — the silent drop was the one state with no defender. Review landed on removal; the fallback stands as the documented alternative should the slot ever return ahead of a full feature.
Verification
No ImageBlock / harness type: 'image' block is constructed anywhere outside RFC records; the codec's inbound ACP-image rejection keeps its tests; and the adapter/codec/compaction switches handle the case through their unknown-block default arms, pinned by the plugin-added-block tests.
Consequences
Re-adding a core vocabulary type later touches several packages at once — but that coordinated change is the shape a real multimodal feature needs anyway (adapter mapping, ACP advertisement, compaction pricing), and none of it existed to preserve.