Read a wiring error

Task. A composition does not compile and the error is four hundred characters of your own contract. This page is how to read it.

The rule: read the last line, and read it from the end

Every gate in this framework refuses a call by putting a sentence in the parameter type the argument failed to match. TypeScript prints a parameter type it could not match, so the sentence prints — and it prints last, because TypeScript names the source type first and the source is your own contract, your own piece, your own module.

So the shape is always the same:

error TS2769: No overload matches this call.
  The last overload gave the following error.
    Type '<three hundred characters of your own types>' is not assignable to type '<the sentence, and what is wrong>'.

The first two lines are boilerplate. The third line's tail is the whole message.

The width is not fixable from inside the packages. It is in the type arguments — your contract, expanded — not in a name any package could alias, which is why the marker is a whole sentence rather than a label: it is the part you can act on, and it sits where your eye ends up.

The markers

Marker	What happened	Where the fix goes
UNSATISFIED DEPENDENCIES — nothing provides	Something in the graph reads a port nothing provides. The port is named by its id — a bound unit module's own unmet needs join this same channel, since they travel published in the starter's type exactly like an import's.	provides, or an import that provides it. Not exports.
NO RUNTIME	The module exports no port declared over RuntimePort, so there is nothing to boot.	Compose a runtime — HttpModule/http(), TemporalModule, AmqpModule — and export its port.
UNSATISFIED RUNTIME PORTS	The runtime resolves a port the module does not export.	exports. The module's own, never a fork's.
UNCOVERED CONTROLLERS / HANDLERS / ACTIVITIES	An array of pieces leaves a contract leaf unimplemented. The leaf is named beside the marker.	The array: add the missing piece.
OVERLAPPING CONTROLLERS	One piece's path sits inside another's, so both would implement the same procedures.	The array: drop one, or mint them at sibling paths.
UNSLICEABLE CONTRACT KEY	A top-level contract key contains a dot, which a piece path cannot encode.	Serve that contract with the { inject, sync } form instead.

An unmet dependency

A root that imports http() and forgets to provide the router:

const OrderApi = Module("OrderApi")({
  imports: [http()],
  exports: [HttpHandler],
});

await runMain(OrderApi);

error TS2345: Argument of type 'Module<HttpHandler, ConfigInvalid, Env | OrpcRouterPort>' is not assignable to parameter of type 'Module<HttpHandler, ConfigInvalid, Env | OrpcRouterPort> & { readonly "UNSATISFIED DEPENDENCIES — nothing provides": "OrpcRouter" }'.

"OrpcRouter" is the port's id — what someone wrote in Port("…") — not its type. That is deliberate: a starter's own generic port is its whole contract as a type, hundreds of characters that truncate before a name is reached. Several unmet ports print as a union: "Logger" | "Mailer".

It is checked before the runtime arms, so a root with two mistakes is told about the one nearest the cause. The fix is a provider, never an export.

An uncovered piece

error TS2769: No overload matches this call.
  The last overload gave the following error.
    Type 'Minted<…, "orders", …>' is not assignable to type 'readonly ["UNCOVERED CONTROLLERS — the contract declares a procedure this array does not cover", "billing.pay" | "users.find"]'.

The marker and the missing leaves arrive together, whatever the array's length: the refusal is a tuple as long as the array you wrote — its head your own elements, which match, and its last element the marker paired with what is missing — so TypeScript lines the two up element by element and reports on the trailing one. The three worker-side and router-side gates share the shape: UNCOVERED HANDLERS names a consumer, UNCOVERED ACTIVITIES a workflow, UNCOVERED CONTROLLERS a procedure path.

A key the contract does not declare

This one is refused at the mint, not at the array, and it is a TS2345 rather than a TS2769 — a much friendlier error, because it lists every path that is valid:

error TS2345: Argument of type '"billing"' is not assignable to parameter of type '"orders" | "orders.place" | "users" | "users.find"'.

If you see this one, read it and stop: any further error on the array below it is a consequence. The array's own gates deliberately stand down when a piece's key is a union, which is what a refused mint looks like from the outside.

Two lines of noise you can turn off

An application that emits no declarations still type-checks declaration emit if its tsconfig.json says declaration: true — and a composition root exported from a module reaches a library's internal brand symbols, so every wiring mistake is preceded by:

error TS4023: Exported variable 'OrderApi' has or is using name 'ID' from external module "…/di/dist/index" but cannot be named.
error TS4023: … name 'SERVICE' …

Set "declaration": false in an application's compilerOptions and they are gone; the error you actually made becomes the first one printed. A library keeps declaration: true, where the check is the guarantee that its consumers can build.

Where to go next

• Compile-time wiring — why the gates are phantom markers on a parameter, and what each one costs.
• start and StartOptions — the kernel's own gate, arm by arm.