Keyboard shortcuts

Press ← or → to navigate between chapters

Press S or / to search in the book

Press ? to show this help

Press Esc to hide this help

Auto-fix

The studio can fix a diagnostic for you instead of asking you to hand-edit the source. This page is the author-facing tour; the full design (the Fixer model, the batching algorithm, the policy layering) is docs/autofix-spec.md, and the command-line equivalent is brink fix.

What a fix is

A fix is a small, targeted edit that discharges one diagnostic — the same kind of change you’d make by hand, computed for you. Diagnostics stay exactly what they always were (a squiggle, a Problems-panel row); a fix is just an optional extra action attached to one.

Every fix is labeled with a tier, so you know how far it’s allowed to go before you click it:

  • Safe — the result behaves exactly the same as before; only the redundant or already-inert text changes. Safe fixes are the ones “Fix all safe” batches for you without asking case by case.
  • Suggested — probably what you meant, but it changes what the story does or removes text you wrote (for example, trimming an extra argument from a call). Each one is a deliberate, one-at-a-time click unless your project has explicitly promoted that diagnostic code to batch automatically (see Policy below).
  • Placeholder — the fix can’t complete the thought for you; it removes the ambiguity and drops your cursor where you still need to type something. Placeholder fixes are never batched. The studio’s tier button doesn’t show this wire spelling to authors — it reads Needs input instead (see Where fixes appear below).

A fix never appears for a diagnostic it can’t actually clear, and applying one always re-runs analysis — if a fix doesn’t make its own diagnostic go away, that’s treated as a bug in the fixer, not something the studio hides.

Where fixes appear

All of these are different doors onto the same underlying fix — pressing “Fix” on a Problems row and picking the identical entry from the editor’s context menu produce the same edit.

  • Problems panel — a row with a fix available shows a Fix button (labeled with its tier) beside the diagnostic; right-clicking a row lists every fix offered for it alongside the existing suppress actions. The panel’s header shows a Fix all safe (N) button once at least one Safe fix is available anywhere in the project — N is an exact count, not an estimate, so the button never promises more than clicking it will do.
  • Editor context menu — right-click a squiggle to get the same fix entries (each still labeled with its tier) for the diagnostic under the pointer, plus a trailing Fix all safe in this file entry that only appears alongside at least one offered fix.
  • Code-actions menu — the lightbulb-style menu at the cursor lists the fixes for diagnostics whose own range covers the cursor position (not just any diagnostic nearby); choosing one applies it immediately, and a Placeholder fix moves your cursor into the hole it left.
  • Command palette — “Fix: Fix all safe in project” and “Fix: Fix all safe in this file” run the same Safe-tier batch as the Problems panel’s header button, scoped to the whole project or to whichever file is focused.
  • Fix on save — Settings ▸ Saving ▸ Fix on save applies fixes automatically each time you save a file: Off, Safe fixes only, or Everything the project allows (which also includes any Suggested-tier code your project’s brink.toml has promoted to "auto", see Policy). This setting is a personal ceiling, not a project-wide switch — it can only make what happens on save more conservative than what the project allows, never less; a project promoting a code to "auto" doesn’t force it onto an author who has chosen “Safe fixes only”.
  • Other editors, via the LSP — brink-lsp offers each fix as a standard quickfix code action tied to its diagnostic, plus the source.fixAll.brink action that VS Code (and any client supporting fix-on-save code actions) runs automatically on save — the same Safe-tier batch the studio’s own on-save setting runs.

Policy: the [fix] table in brink.toml

A project can adjust the default tier behavior per diagnostic code with a [fix] table:

[fix]
E025 = "auto"   # promote a Suggested fix to batch automatically in this project
E014 = "off"    # never offer this fixer here
# a code left out of the table keeps its tier's default:
#   Safe -> batched automatically, Suggested -> offered per click, Placeholder -> never batched

The three values:

ValueMeaning
"auto"Batch this code’s fixes automatically wherever a batch runs — this is how a Suggested-tier fixer gets included in “Fix all safe” and fix-on-save. (A Placeholder-tier code can never be batched, no matter what the table says.)
"ask"The default: offered as a one-click fix, but not swept up by a batch unless it’s already Safe-tier.
"off"Withdraw the fix entirely — it stops being offered on any surface, even a single click.

[fix] travels with the project like [lints] does, so the CLI, the LSP, and the studio all read the same policy. In Settings, the same lint table that shows each diagnostic’s severity also carries a Fix column with these three values — editing it writes straight into brink.toml’s [fix] table, the same way changing a severity writes into [lints]. A code can have a [fix] entry independently of whether it’s configurable in [lints]; the two tables are keyed by the same diagnostic code but are otherwise unrelated.

Today’s Safe fixers

These are the diagnostic codes that currently ship a Safe-tier fixer — the ones “Fix all safe”, fix-on-save, and source.fixAll.brink will batch without asking. (Suggested-tier fixers exist too — E025, E063, E080, and E081 today — but a one-at-a-time click is expected for those, so they’re left out of this list; no Placeholder-tier fixer ships yet. See docs/autofix-spec.md §9 for the full registry.)

CodeWhat it fixes
E014Removes an effect-free ~ logic line — one that does nothing at all.
E031Trims a function call’s extra arguments down to the number its declaration actually accepts.
E092Removes a redundant #@public/#@private directive that only restates the module’s own default.
E095Removes a stale #@was tag that already names the definition’s current name — there’s nothing left to migrate.
E110Rewrites the deprecated #@effects(…) directive spelling to the current @[effects(…)] annotation.
E176Trims a divert-with-args site’s (-> knot(args), tunnel call, thread-start) extra arguments down to its resolved target’s declared parameter count — E031’s sibling for the divert-call shape.

This list will grow as more codes get Safe fixers; it’s read out of the FIXERS registry in crates/internal/brink-ide/src/fix.rs on main, so check there (or brink fix --dry-run on your own project) for the current truth rather than trusting a page that can drift.