Ask the standard library through muxt.Checker by crhntr · Pull Request #149 · typelate/muxt

crhntr · 2026-09-14T23:42:48Z

Route resolution asks a muxt.Checker about the standard library instead of searching imports. load.StandardLibrary is the real implementation, and internal/muxt/muxttest provides a mock plus in-memory type checking, so muxt tests no longer load a module.

Part 4 of 8, stacked on #148. Replaces #145.

🤖 Generated with Claude Code

https://claude.ai/code/session_01UjkpA4fvZ7xQAsY65Beprp

Copilot

🟡 Changes recommended

Critical findings remain in standard-library JSON lookup and repeated path-value bindings, with a moderate production-adapter test gap.

Get a fresh assessment by requesting another Copilot review.

Pull request overview

Refactors route resolution to query a muxt.Checker for standard-library types, with production and in-memory implementations.

Changes:

Adds checker-backed resolution and generation metadata.
Updates standard-library loading, CLI wiring, fixtures, and tests.
Documents the checker-based architecture.

File summaries

File	Summary / review notes
`internal/source/source.go`	Removes standard-library import data.
`internal/muxt/unmarshal.go`	Moves parsing classification to the checker.
`internal/muxt/testdata/example/std.go`	Adds test stand-in types.
`internal/muxt/testdata/example/methods.go`	Updates fixture methods to use stand-in types.
`internal/muxt/testdata/example/go.mod`	Removes obsolete fixture module metadata.
`internal/muxt/testdata/example/functions.go`	Updates fixture functions to use stand-in types.
`internal/muxt/path_value_types_test.go`	Critical (1 vote): incompatible repeated bindings can reuse a string for an `int` parameter and generate uncompilable code; reject differing types or preserve separate raw and parsed locals. Also applies on line 54.
`internal/muxt/muxttest/muxttest.go`	Adds the mock checker and in-memory type-checking helpers.
`internal/muxt/definition.go`	Stores path marshaler metadata.
`internal/muxt/checker.go`	Defines the `Checker` interface.
`internal/muxt/call.go`	Nit (3 votes): correct the `Direct` comment’s “not parses” and “not binds” grammar.
`internal/muxt/call_test.go`	Migrates call-resolution tests.
`internal/load/stdlib.go`	Moderate (1 vote): add focused adapter tests. Critical (1 vote): include `encoding/json` in load patterns so `json.RawMessage` resolves for `unmarshalJSON(body)`.
`internal/load/source.go`	Stops hydrating the obsolete import graph.
`internal/generate/template_route_path.go`	Uses resolved text-marshaler information.
`internal/generate/source_test.go`	Adds in-memory generation fixtures.
`internal/generate/routes.go`	Passes the checker and consumes resolved metadata.
`internal/generate/routes_test.go`	Tests generation metadata and errors.
`internal/cli/commands.go`	Wires the production checker into generation.
`CLAUDE.md`	Documents the checker-based architecture.

Review details

Suppressed comments (2)

internal/load/stdlib.go:17

Please add focused tests for this new production Checker adapter. The internal/load tests currently do not cover StandardLibrary's reserved-type mappings, transitive indexing, or text-interface checks, so regressions here can make CLI route generation bind or parse against the wrong types while the mock-backed muxt tests remain green.

func StandardLibrary(pl []*packages.Package) muxt.Checker {
	return standardLibrary(indexImports(pl))

internal/muxt/path_value_types_test.go:54

This case accepts incompatible repeated bindings: the nested Echo(id) binds id as string, while the outer Wrap requires int. Generation shares the parsed-name set, so it reuses the raw idPathParam for the later argument and emits a call to Wrap(..., int) that cannot compile. Reject incompatible repeated path-value types during resolution (or preserve separate raw and parsed locals) instead of asserting this route is valid.

		{name: "a nested call that takes a string decides before a later int", template: "GET /{id} Wrap(Echo(id), id)", param: "id"},

Files reviewed: 20/20 changed files
Comments generated: 3
Review effort level: Lite

💡 Add a code-review agent skill or configure MCP servers for context-aware, tailored reviews. Learn more in the docs.

Copilot

🟡 Changes recommended

A critical path-parameter/callback naming collision can produce invalid generated code and must be handled before approval.

Get a fresh assessment by requesting another Copilot review.

Review details

Files reviewed: 20/20 changed files
Comments generated: 1
Review effort level: Lite

What route resolution needs to know about the standard library is narrow: the type each reserved argument binds to, whether a type marshals to or from text, and what a file header and a raw JSON message are. It found those by searching the loaded package's imports for net/http, context, encoding and the rest, so testing resolution meant loading or stubbing those packages, and a test stated the rules against one version of them. muxt.Checker asks exactly those questions. load.StandardLibrary is the one implementation, answering from the official standard library a run loaded. source.Package drops the imports it carried only for this. Resolution also records what generation used to work out from standard library types -- whether an argument passes to its parameter as it is, how it otherwise parses, and whether a path value formats with MarshalText -- so generate asks the standard library nothing and only forwards the checker to resolution. internal/muxt/muxtfakes holds the Checker fake, generated by counterfeiter, and internal/muxt/muxttest builds one from what a test says the standard library looks like: StandInChecker binds each reserved identifier to the stand-in of that shape the test's own package declares, and NewChecker with Binds, ParsesFromText and FormatsAsText says it a piece at a time. muxttest also type checks source that may import nothing. So muxt's tests declare stand-in types in their own source (a Request, a Context) rather than loading a module, and TestArgument, which did load one, now runs through muxt's exported API from muxt_test -- the fake imports muxt, so a test inside the package could not link it. TestPathValueTypes and TestPathValueTextMarshaler state what resolution records for a path parameter, and TestHandlerGenerationLeavesTheRouteAsResolved that generating a handler leaves its route as resolved -- the copy the generation fixes made. Generation reports an argument with no request value to parse, such as an sse message, as it did before. load.StandardLibrary, and what generation reads from resolution, are held by the integration suite here; unit tests over the real standard library come with the in-memory loader two changes on. Every generated file in the integration suite is unchanged. Assisted-by: Claude:claude-opus-5 gofumpt

A large share of the integration suite checks that flags mean what they say, and it could only do that by running the whole command: load a package, generate, compile. Deciding what a command line means happens before any of that, but nothing let a test stop there. Each command now builds its configuration -- flags parsed, defaults applied, what cannot work rejected -- and hands it to a runner, which loads the package and runs the implementation. Commands wires the real runners, in run.go; configurationOf wires ones that record what they are handed. TestCommandLineConfigurations states what command lines parse into, as composite literals, and TestCommandLineRejections the command lines refused, with the error a user sees. TestChangeDirectory states the directory -C runs a command in. None of them loads anything. Six commands have runners: the route listing, check, generate, the two template listings and the mutation run. --format is still read when a result is written, and generate-fake-server and explore-module still load in their own RunE; they are left for later. A generated file's header now records the version from the configuration rather than asking the build info again, so the version a run writes is the one its configuration holds. Assisted-by: Claude:claude-opus-5 gofumpt

generate's own tests covered a few percent of it: what a handler looks like for a form struct, an sse route, a status code in the name or a redirect in the template was only stated by the integration suite, which compiles and runs every scratch module and takes over a minute. internal/load/loadtest builds what a package load returns without loading the package graph: it writes the files, type checks them in memory, and imports the official standard library from the export data go list reports for it, reading it with gcexportdata -- as go/packages does -- and giving each package the imports go list reports, which is how check finds fmt behind html/template. The standard library is whichever the go command in use provides. A test binary pays a few hundred milliseconds once to read it. TestStandardLibrary states load.StandardLibrary's answers against it, and TestHydration the order load's hydration reports a missing package, a missing receiver and a variable that does not evaluate. internal/generate/testdata/generate/*.txtar holds one case per feature: the receiver's Go source, the templates, and the files and log lines generation produces. An archive holds the configuration it generates with, in its own config.json, beside the command line that parses into it; nothing outside the archive says what a case is. The directory an archive is in names the command, so a case runs alone as -run TestSnapshots/generate/sse. Reading it is encoding/json/v2, which the module now asks for Go 1.27 to have. TestSnapshots loads the case through loadtest and load.GenerateSource, as muxt generate does, generates, and compares; the 32 cases cover most of the package. It also fails on a generated file that imports a package it does not use. go test -run TestSnapshots -update rewrites the want/ files, and the diff is the review. A snapshot says what the generator does, not that the result compiles or serves requests; that stays the integration suite's job. Assisted-by: Claude:claude-opus-5 gofumpt

…mory muxt check is the command the integration suite runs most, and its reports -- a field the data type lacks, a template nothing renders, a route waiting for muxt generate -- were only stated there, behind a package load per script. internal/analysis/testdata/<command>/*.txtar holds cases for check, the route listing, and the template caller and call listings. The directory an archive is in names the command it runs, so a case runs alone as -run TestSnapshots/list-template-calls/calls, and the archive holds the configuration it runs with, in its own config.json, beside the command line that parses into it. A listing's configuration needs nothing to read as JSON: regexp.Regexp writes itself as the text it was compiled from, and internal/configjson says the rest -- a field the command line left alone is null rather than an empty list, and a member a configuration does not declare is an error. TestSnapshots loads the case through loadtest and internal/load's hydration, as the commands do, and compares what the analysis reports. Assisted-by: Claude:claude-opus-5 gofumpt

The mutation run's planning -- which templates each ExecuteTemplate call reaches, with what dot, and which variations apply -- read the loaded templates, the checker built on them, and the syntax trees it searched for the string literal a template was written in. So stating any of it took a module on disk and the go command. Planning now runs on an input: the source.Package internal/load reads. loadInput builds one with the go command; planFrom and revisionOf read nothing else. A template's string literal is found by parsing its file's text, which planning already holds, instead of searching the loader's syntax trees. With that, nothing reads load.Templates, and it goes. internal/mutation/testdata/test-template-mutations/*.txtar snapshots a dry run's report for ten cases -- a literal template, partials and trims, a template pattern, skipped mutants, the operand budget, other delimiters, a --diff revision, and the errors a plan returns -- each loaded through loadtest and planned in milliseconds. An archive holds the configuration it plans with, in its own config.json: regexp.Regexp writes itself as the text it was compiled from, so a pattern reads as the command line wrote it, and a pattern the command line left alone is null -- "" would be a pattern matching everything. As in the other two suites, the directory names the command, so a case runs alone as -run TestSnapshots/test-template-mutations/diff. CLAUDE.md's recipes for a feature, a bug and an error now start from the unit test at the layer that owns the behavior, and say what the in-memory loader cannot stand in for. Assisted-by: Claude:claude-opus-5 gofumpt

The snapshot archives hold the configuration they run with, and reading one is encoding/json/v2: it knows how to read a *regexp.Regexp, which v1 could only do through a second struct carrying the pattern's source. Everywhere else muxt reads or writes JSON went with it, so one library answers "how does muxt read JSON": the module list, the overlay each mutant is delivered through, the generated file's import map, and a command's --format=json result. Two differences the standard library documents, and the integration suite insisted on: - omitempty in v2 omits an empty JSON value -- null, "", [], {} -- and no longer a zero number or a false. The fields that meant the latter say omitzero now, so a mutant that took no measurable time still reports no seconds, and a module listing still leaves out the flags a package does not set. - Reading is case sensitive, and a member the target does not declare is an error rather than silence. Every name muxt reads was already written by muxt or by the go command, so nothing had to change. - Writing makes no promise about map order, writes a nil list or map as [] or {}, and escapes neither <, >, & nor U+2028 and U+2029, where v1 sorted map keys, wrote null and escaped them. --format=json is read by scripts, so it is written with the options that say v1's choices, and TestWriteResultJSON states each one. A listing's import map now writes through the encoder it is handed (MarshalJSONTo), so those options reach it too, rather than a separate Marshal deciding its order. The reports and listings are byte for byte what they were. Assisted-by: Claude:claude-opus-5 gofumpt

A few loops spelled out what the slices and maps packages already name: gathering a map's keys and sorting them, asking whether a list holds something, copying a list, and a union of keys de-duplicated by hand. - slices.Sorted(maps.Keys(m)) where keys were gathered and then sorted: the module listing's directories, muxttest.Check's file names, and the template source files generation walks. sort is no longer imported anywhere in muxt's own code. - slices.ContainsFunc where a loop or an IndexFunc whose index went unused only asked whether something is there: marshalJSON refusing the execute callback, and a receiver method already in the interface. - slices.Clone for File.ImportSpecs' copy; its callers only range over the result or take its length. - sortedKeys in the generate snapshot harness appends every map's keys, sorts and compacts, rather than checking Contains before each append. Loops that find an element to change in place, build a different type, or return early with more than a yes or no stay as they were. Every generated file and report is unchanged. Assisted-by: Claude:claude-opus-5 gofumpt

reduces complexity with handling execute

A Definition now carries its path as a slice of Segment values, each a literal or a {name} / {name...} wildcard. After ResolveCall a wildcard segment also knows the type its value parses into and whether that type marshals as text, replacing the pathValueTypes, pathValueMarshalers and pathValueNames fields and the PathValueIdentifiers, ArgumentType and PathValueTextMarshaler methods. Route path generation iterates the segments instead of re-splitting the pattern, and the muxt package answers whether an argument names a path parameter through ArgumentIsPathParameter and PathParameter. A segment that opens a brace without closing it as a wildcard is now rejected when the definition is parsed rather than at ServeMux registration. Assisted-by: Claude:claude-fable-5-1 gofumpt goimports staticcheck

A nested call argument records the ResultShape its results were validated against, so the generator switches on that instead of inspecting the signature again with go/types. Assisted-by: Claude:claude-fable-5-1 gofumpt

ResolveCall records whether the template data's result type has a StatusCode method or field, so the generator no longer builds a StatusCoder interface with go/types to probe the result itself. Assisted-by: Claude:claude-fable-5-1 gofumpt

Mutation testing showed the remainder wildcard, the unknown segment error and the argument predicates had no test in this package. ArgumentIsLastEventID no longer checks for a path parameter of that name, since the name is reserved and cannot be one. Assisted-by: Claude:claude-fable-5-1 gremlins gofumpt

The argument parser took the call's signature only to look up each parameter's type in step with the call's arguments, which the resolved Argument already carries. The arity check it repeated is muxt's. The result type it threaded through five functions was never read. Assisted-by: Claude:claude-fable-5-1 gofumpt goimports

A Type formats a Go type against a file's imports and answers whether it is a string, which basic kind it has, and whether it is identical to another, so packages after resolution can stop importing go/types. Assisted-by: Claude:claude-fable-5-1 gofumpt

Argument.ParamType becomes an accessor returning a source.Type, and a FieldBinding names its field and returns its element type the same way. File.TypeExpr spells a source.Type against the file's imports, and the form, multipart, JSON body and parse helpers take one. Assisted-by: Claude:claude-fable-5-1 gofumpt goimports

Assisted-by: Claude:claude-fable-5-1 gofumpt goimports

Definition.ResultDataType names the template data's result type for both handler shapes, and the callback and scope type accessors return a source.Type. writeHeadersAndStatusCode drops the result type it stopped reading. Assisted-by: Claude:claude-fable-5-1 gofumpt goimports

Assisted-by: Claude:claude-fable-5-1 gofumpt goimports

Resolve parses every templates variable's routes and resolves each call, inferring methods against an empty Receiver struct when no receiver type is named, so callers hand generation resolved definitions. Assisted-by: Claude:claude-fable-5-1 gofumpt goimports

TemplateRoutesFiles takes the definitions muxt.Resolve produced instead of the receiver type and checker it resolved them with, so generation reads only what resolution recorded and stops importing go/types. The CLI and the snapshot harness resolve before they generate. Resolution notes now print before generation logs rather than between them. Assisted-by: Claude:claude-fable-5-1 gofumpt goimports

Assisted-by: Claude:claude-fable-5-1 gofumpt

Assisted-by: Claude:claude-fable-5-1 gofumpt goimports

Assisted-by: Claude:claude-fable-5-1 gofumpt

Assisted-by: Claude:claude-fable-5-1 gremlins gofumpt

Assisted-by: Claude:claude-fable-5-1 gopls gofumpt

Copilot AI lite review requested due to automatic review settings September 14, 2026 23:42

This was referenced Sep 14, 2026

Hand each command its configuration, and test what command lines mean #150

Merged

Isolate packages.Load behind internal/load #145

Closed

Copilot started reviewing on behalf of crhntr September 14, 2026 23:43 View session

Copilot AI reviewed Sep 14, 2026

View reviewed changes

Comment thread internal/load/stdlib.go

Comment thread internal/muxt/path_value_types_test.go Outdated

Comment thread internal/muxt/call.go Outdated

crhntr force-pushed the split/3-source-package branch from d59de39 to 38a38d8 Compare September 16, 2026 01:36

crhntr force-pushed the split/4-checker branch from cb82817 to 4ab8fad Compare September 16, 2026 01:36

crhntr force-pushed the split/3-source-package branch from 38a38d8 to db40f24 Compare September 16, 2026 06:07

crhntr force-pushed the split/4-checker branch 2 times, most recently from 4ffbdd1 to d527e46 Compare September 16, 2026 06:22

crhntr force-pushed the split/3-source-package branch from db40f24 to 52afbac Compare September 16, 2026 06:22

crhntr requested a lite review from Copilot September 16, 2026 06:23

Copilot started reviewing on behalf of crhntr September 16, 2026 06:23 View session

Copilot AI reviewed Sep 16, 2026

View reviewed changes

Comment thread internal/muxt/path_value_types_test.go Outdated

crhntr force-pushed the split/3-source-package branch from 52afbac to edb59b9 Compare September 16, 2026 06:38

crhntr force-pushed the split/4-checker branch from d527e46 to a8856ac Compare September 16, 2026 06:38

crhntr force-pushed the split/3-source-package branch from edb59b9 to 49552c3 Compare September 16, 2026 06:42

crhntr force-pushed the split/4-checker branch from a8856ac to 8ebd9fa Compare September 16, 2026 06:42

crhntr force-pushed the split/3-source-package branch from 49552c3 to 3b51c46 Compare September 16, 2026 06:58

crhntr force-pushed the split/4-checker branch from 8ebd9fa to 5f2f882 Compare September 16, 2026 06:58

Base automatically changed from split/3-source-package to main September 16, 2026 07:18

crhntr force-pushed the split/4-checker branch from 5f2f882 to fd50bdf Compare September 16, 2026 07:26

crhntr added 8 commits September 28, 2026 09:50

organize test colaborator in fake package

7e9d555

crhntr added 26 commits September 28, 2026 09:50

factor out index Route

b067925

factor out callFuncExpression and reduce types.Signature passing

196271d

split executeHTMLTemplateHandler

396424f

reduces complexity with handling execute

standardize initHandlerScope

d6f5dcd

factor out writeHeadersAndStatusCode

b7ea231

classify nested call results in muxt

55e1902

A nested call argument records the ResultShape its results were validated against, so the generator switches on that instead of inspecting the signature again with go/types. Assisted-by: Claude:claude-fable-5-1 gofumpt

record where a result offers its status code

5cfeeb4

ResolveCall records whether the template data's result type has a StatusCode method or field, so the generator no longer builds a StatusCoder interface with go/types to probe the result itself. Assisted-by: Claude:claude-fable-5-1 gofumpt

add source.Type

6ab9f0b

A Type formats a Go type against a file's imports and answers whether it is a string, which basic kind it has, and whether it is identical to another, so packages after resolution can stop importing go/types. Assisted-by: Claude:claude-fable-5-1 gofumpt

render path segment types through source.Type

bcd57be

Assisted-by: Claude:claude-fable-5-1 gofumpt goimports

render call signatures through source.Type

1625ed3

Assisted-by: Claude:claude-fable-5-1 gofumpt goimports

remove the go/types renderer from generate

7b74050

Assisted-by: Claude:claude-fable-5-1 gofumpt goimports

add muxt.Resolve

05b1154

Resolve parses every templates variable's routes and resolves each call, inferring methods against an empty Receiver struct when no receiver type is named, so callers hand generation resolved definitions. Assisted-by: Claude:claude-fable-5-1 gofumpt goimports

split logging from receiver method collection

c108f62

Assisted-by: Claude:claude-fable-5-1 gofumpt

format path values from a source.Type

d371c7f

Assisted-by: Claude:claude-fable-5-1 gofumpt goimports

gofumpt the example fixture

07caec7

Assisted-by: Claude:claude-fable-5-1 gofumpt

test result shape rules mutation testing left open

a89d9a6

Assisted-by: Claude:claude-fable-5-1 gremlins gofumpt

rename StatusCodeSource to ResultStatusCode

c948a0d

Assisted-by: Claude:claude-fable-5-1 gopls gofumpt

rename muxt.Resolve to ResolveDefinitions

d890513

Assisted-by: Claude:claude-fable-5-1 gopls gofumpt

rename ResultDataType to ResultType

1e1adda

Assisted-by: Claude:claude-fable-5-1 gopls gofumpt

rename logResolution to logResolutionNotes

f1433ba

Assisted-by: Claude:claude-fable-5-1 gopls gofumpt

crhntr force-pushed the split/4-checker branch from 22be05b to f1433ba Compare September 28, 2026 16:53

crhntr merged commit 7e70895 into main Sep 28, 2026
2 checks passed

crhntr deleted the split/4-checker branch September 28, 2026 18:07

Navigation Menu

Ask the standard library through muxt.Checker - #149

Ask the standard library through muxt.Checker#149
crhntr merged 34 commits into
mainfrom
split/4-checker

crhntr commented Sep 14, 2026

Uh oh!

Copilot AI left a comment

Uh oh!

Uh oh!

Uh oh!

Uh oh!

Copilot AI left a comment

Uh oh!

Uh oh!

Uh oh!

Reviewers

Assignees

Labels

Projects

Milestone

Development

Uh oh!

2 participants

Conversation

crhntr commented Sep 14, 2026

Uh oh!

Copilot AI left a comment

Choose a reason for hiding this comment

🟡 Changes recommended

Suppressed comments (2)

Uh oh!

Uh oh!

Uh oh!

Uh oh!

Copilot AI left a comment

Choose a reason for hiding this comment

🟡 Changes recommended

Uh oh!

Uh oh!

Uh oh!

Reviewers

Assignees

Labels

Projects

Milestone

Development

Uh oh!

2 participants