revspot-mcp

Revspot's image-generation MCP server. It implements the DTC-ads tool surface (generate_image, show_marketing_studio, and friends) so that any client or skill written against that surface works here unchanged.

Run it

npm install
cp .env.example .env.local     # fill in OPENAI_API_KEY at minimum
npm run dev

The server is POST /api/mcp (JSON-RPC, MCP over HTTP). It exposes 13 tools:

generate_image            generate_image_batch      jobs_wait
job_status                show_marketing_studio     show_generations
show_generation_by_ids    show_marketing_studio_generations
edit_image                media_upload              media_confirm
models_explore            balance

Related MCP server: ImageMcp

Before you deploy

npm run predeploy

Five checks; non-zero exit on any failure.

widgets:version   widget resource versions consistent
widgets:parse     every widget script parses
widgets:paint     widgets render against a strict host
receipts:diff     request-assembly conformance (see below)
tsc --noEmit      types

widgets:paint needs REVSPOT_BACKEND_URL pointing at a running instance.

receipts:diff — the check that matters

lib/core/dtc-ads/assets/ holds 102 pinned conformance fixtures: for each one, a set of tool parameters and the exact downstream request that surface is expected to produce. The gate rebuilds every fixture through our assembler and requires a byte-for-byte match. Currently 102/102, including the brand-kit path.

This is a golden-file regression suite, and it earns its keep. Code review found nothing; diffing against the fixtures found three real defects in a day:

• product image URLs emitted as site-relative paths where the spec is absolute, so the model was handed a path fragment instead of an image

• medias[] accepted and validated, then never read — caller reference images reached neither the payload nor the provider

• a brand-kit path that sent an opaque UUID while switching on the brand-kit system prompt, telling the model to hold a brand it was never shown

Prefer evidence over inspection. Refresh the fixtures whenever the assembler, catalogue or system prompts change.

Canvas table — read before touching aspect ratios

lib/core/image-generation/openai.ts

The image provider enforces two rules, quoted from its own rejections: both sides divisible by 16, and within a per-resolution pixel budget. The canvas sizes in OBSERVED satisfy both and no formula reproduces them — 3:4 at 2k is 1744×2336, not 2× the 1k 880×1168. The relationship is bespoke per ratio.

So there are two outcomes: a canvas backed by a measurement (OBSERVED), or auto. Do not compute one. An earlier invented table produced sizes the provider rejects outright and broke 17 of 45 aspect/resolution combinations.

COMPUTED holds 4:5 only, and is the documented exception. 4:5 is the Meta feed standard, and each of its three sizes is the largest exact-0.8 canvas satisfying the provider's own two rules. They are marked observed: false so a run receipt states plainly that the number rests on arithmetic rather than a measurement. Before this existed, asking for 4:5 silently returned a 1254×1254 square.

Widgets

Three MCP-Apps panels — the generation gallery, the ad-format picker, and media upload — served as ui://revspot/<name>.<version>.html from lib/core/dtc-ads/widgets.ts.

Hosts cache widget HTML against its URI, so markup changes are invisible to any client that already opened a panel. widgets:version enforces this: change the markup without bumping WIDGET_VERSION and the gate fails with the old and new hashes. Bump the constant, commit the regenerated lockfile, and clients refetch.

gate/ — behavioural conformance

Verifies that an agent driving this server chooses the same tools and the same ad templates it would on the reference surface. It deliberately does not compare images: the image model samples, so no surface reproduces its own output.

Latest, Claude driving, 24 briefs:

ours vs reference        24/24  100.0%
reference vs itself      23/24   95.8%   <- the ceiling
ours vs ours             23/24   95.8%

100% is not the target. The reference surface only reproduces itself 95.8% of the time, because template choice over an overlapping catalogue is a judgement call. Start with gate/RUN-IN-FRESH-SESSION.md.

Method note that costs a day if ignored: MCP tool schemas are cached per session, and subagents inherit the cache. After ANY edit to a tool description or parameter doc, re-test from a brand-new session and assert the new wording is actually in the schema the agent received. Testing inside the session that made the change already produced one false negative here.

What is deliberately not here

The earlier Revspot Static Studio tool surface — show_static_studio, create_product_pack, generate_static, list_static_runs — and its prompt-compiler, template and render-spec chain. It collided with the current surface (an agent seeing both generate_image and generate_static picked arbitrarily) and was vertical-locked to real estate, where this surface is vertical-neutral.

NATIVE_TOOL_REPLACEMENT in the route survives it on purpose: clients cache tool lists, so a session opened before the cutover still calls the old names and should be pointed at the current equivalent rather than just failing.

Also dropped: the kie and openrouter image providers. openai is the one measured to produce the correct canvases; kie is a reseller that returns a non-native size.

Naming — what was deliberately left alone

The rename swept the codebase, with four exceptions that are load-bearing rather than cosmetic. Each is commented at its definition:

.prizm-data/                     on-disk data directory
data/prizm-product-packs.json    on-disk store file
prizm_asset_intelligence_v1      persisted schema tag inside records
/prizm-assets/, /prizm-outputs/  legacy URL prefixes, still resolved

The first three exist on any already-deployed volume; renaming them orphans every product pack and run record written before the change. The last two are accepted and rewritten onto assets/ and outputs/ in servedUrlToFilePath, because pack records persist the URL that was current when they were created.

Rename any of them only alongside a migration.

Known open items

1. Twelve tools on the reference surface that we do not implement. Highest priority are media_import_url and media_upload_widget, which the generate_image documentation names directly — an agent that knows the surface will reach for them and hard-fail. Then show_medias, then the transform tools (upscale_image, reframe, outpaint_image, remove_background), whose absence turns "make it bigger" into a re-generation with different copy.

2. No brand-kit store. A bare brand_kit_id is refused with an explanatory error rather than silently degraded; an inline brand_kit object works.

3. No get_cost preflight, so cost cannot be quoted before running.

4. Generation history has no created_at and no date filter, so "what did I make today" cannot be scoped server-side.

5. Ambiguous surface: batch_size vs count, url vs scrap_url, image_style aliasing ad_format.

6. Jobs occasionally accept and sit in queued without starting. Re-submitting clears it; a 15-minute watchdog reaps them. Root cause not diagnosed.

7. Concurrency cap is 8; larger batches need a queue that waits for slots.

Things that will bite you

• Product packs do not transfer between instances. Rebuild them with the SAME images. A pack with the right name and wrong images produced a different building and invalidated a full 18-creative comparison. Verify image by image, not by title or count.

• style_id has no default and is the dominant creative driver. Its parameter description is load-bearing — wording there changed which templates agents picked. Treat tool descriptions as behaviour, not documentation.

• Never reconstruct a record from a read that may have missed. A {...(await get(id))!} spread persisted a row with no id and no createdAt; the listing sorted on createdAt.localeCompare and threw. Because activeJobCount() calls that listing at the top of every generate, one bad row took generation down completely, and a restart could not clear it.