Diagnostics

September 22, 2026 · View on GitHub

Every problem the compiler finds is reported as a diagnostic: a severity, a stable code, a message, and the line and column it came from. This page is the catalogue of those codes.

A message is written for a person and gets reworded whenever a clearer wording is found. A code never changes. So a code is what you match on, suppress on, and group by - anything reading the message text breaks the next time the message is improved.

Reading a diagnostic

The CLI prints a diagnostic in the format editors and build servers already parse - the file, the position, the severity, the code, and the message - followed by the offending line and a caret:

nested/broken.play(3,5): error PLAY0028: Unknown slice type 'Wat' - expected StateChange, StateView, Automation or Translate
    3 |     slice Wat DoIt
      |     ^

There are three severities. Error means the document does not compile. Warning means the document compiles but something is very likely wrong - almost always a name nothing declares. Information means something worth knowing that changes nothing.

Why the codes read `PLAY`

The prefix is PLAY, after the .play documents this compiler reads.

Cratis Arc has its own catalogue, the SP codes, for generating a .play document from C# source. The two run one after the other - Arc generates a document and hands it straight to this compiler to read back - so both sets of diagnostics land in the same build log. A shared prefix would make SP0034 and a compiler code of the same number indistinguishable at a glance and identical to a SP\d{4} filter, which is why the prefixes deliberately have nothing in common. Arc's codes describe what the generator could not express; the codes here describe what the compiler could not read.

Codes are permanent

A code is an identifier, not a position in a list.

A number is never reused. When a diagnostic is retired, its number is retired with it and left behind as a gap in the sequence. Handing that number to something else would silently change what an existing suppression means.
A number is never renumbered. Inserting a code in the middle of the catalogue would change the meaning of every code after it.
A new code is appended at the end of the sequence whatever it is about, so the number says when a code was added rather than where it belongs. Use this page, not the numbering, to find the codes for an area.
A code outlives its message. Two constructs hitting the same condition share one code - a property line the parser cannot read reports PLAY0016 whether it sits in a type or in an event.

Reacting to a code

Diagnostic carries the code alongside the severity, the message and the location, so a consumer filters on it directly:

using Cratis.Screenplay;
using Cratis.Screenplay.Diagnostics;

var result = new ScreenplayCompiler().Compile(source);

// A document assembled a piece at a time refers to events the pieces have not introduced yet,
// so that one warning is expected here and everything else is not.
var unexpected = result.Diagnostics
    .Where(diagnostic => diagnostic.Code != DiagnosticCodes.UnknownEvent)
    .ToList();

DiagnosticCodes declares every code in this catalogue as a named constant, so the compiler catches a typo that a string literal would not.

In the editor

The language service behind the VS Code extension and the Monaco editor checks a subset of what the compiler checks, and it reports the compiler's code for every condition in that subset. So the Unknown type 'Foo' you get as a squiggle and the one the CLI prints are the same PLAY0165, and can be looked up here, filtered on, and matched against a build log:

import { diagnosticCodes, validateLines } from '@cratis/screenplay-language';

const unknownTypes = validateLines(lines).filter((issue) => issue.code === diagnosticCodes.unknownType);

diagnosticCodes names the codes the editor reports, the same way DiagnosticCodes names them for the compiler. A ValidationIssue carries the code as code, and it reaches the editor: a Monaco marker gets it as code, a VS Code diagnostic as Diagnostic.code.

A few editor checks carry no code, deliberately. The capture and projection validators enforce structural rules that no compiler run reports - a capture must include a source block, an append block must include a when clause - and there is no PLAY number for something the compiler never emits. Minting one would make this catalogue describe two different tools, which is the thing the PLAY prefix was chosen to avoid. Those conditions are reported without a code until the compiler checks them too.

The catalogue

The document and its top level

Code	Severity	Reported when
`PLAY0001`	Error	A line at the top level of a document opens with a word nothing at that level is declared by.
`PLAY0002`	Error	A `domain` line is not `domain <Qualified.Name>`.
`PLAY0003`	Error	A document declares a domain more than once, and a document has at most one.
`PLAY0004`	Error	`domain` is declared after another construct, and it names what the whole document is about.
`PLAY0005`	Error	An `import` line is not `import <Qualified.Name>`.
`PLAY0006`	Warning	A line is indented with tabs, and Screenplay decides nesting from spaces.

Concepts

Code	Severity	Reported when
`PLAY0007`	Error	A `concept` line is not `concept <Name> : <Type>`.
`PLAY0008`	Error	A concept is declared over a primitive the language does not have.
`PLAY0009`	Error	A value of an enumeration concept is not an identifier.
`PLAY0010`	Error	A line in a concept body opens with a word a concept declares nothing by.
`PLAY0011`	Warning	A value of an enumeration is called `validate`, which the concept body reads as an empty validate block.
`PLAY0012`	Error	A concept gives the reason for an attribute it does not carry.
`PLAY0013`	Error	A concept gives the reason for one attribute more than once.

Types

Code	Severity	Reported when
`PLAY0014`	Error	A `type` line is not `type <Name>`.
`PLAY0015`	Error	A type declares no properties, and a type is the properties it holds.
`PLAY0016`	Error	A property line is not `<name> <Type>`.
`PLAY0017`	Error	A property outside a command is marked as the identifier, which only a command property can be.

Events

Code	Severity	Reported when
`PLAY0018`	Error	An `event` line is not `event <Name>`.
`PLAY0019`	Error	A property of an event is marked as the identifier, and an event never carries its event source id.
`PLAY0020`	Warning	A property called `tag` is read by the event body as a static tag rather than as a property.

Modules, features, slices and layouts

Code	Severity	Reported when
`PLAY0021`	Error	A `module` line is not `module <Name>`.
`PLAY0022`	Error	A line in a module body opens with a word a module declares nothing by.
`PLAY0023`	Error	A `feature` line is not `feature <Name>`.
`PLAY0024`	Error	A line in a feature body opens with a word a feature declares nothing by.
`PLAY0025`	Error	A slot declared by a layout, screen template or dialog template is not an identifier optionally followed by `contributes`.
`PLAY0026`	Error	A line in a layout, screen template or dialog template body opens a block none of them declares anything by.
`PLAY0027`	Error	A `slice` line is not `slice <Type> <Name>`.
`PLAY0028`	Error	A slice is declared with a type the language does not have.
`PLAY0029`	Warning	A line in a slice body opens with a word a slice declares nothing by.

Personas

Code	Severity	Reported when
`PLAY0030`	Error	A `persona` line is not `persona <Name>`.
`PLAY0031`	Error	A policy line in a persona body is not `policy <Name>`.
`PLAY0032`	Error	A line in a persona body opens with a word a persona declares nothing by.

Commands

Code	Severity	Reported when
`PLAY0033`	Error	A `command` line is not `command <Name>`.
`PLAY0034`	Error	A line in a command body opens with a word a command declares nothing by.
`PLAY0035`	Error	A command declares both `produces` and `handler`, which say the same thing two ways.
`PLAY0036`	Error	A command marks more than one property as its identifier.
`PLAY0037`	Error	A `concurrency` line carries anything beyond the keyword.
`PLAY0038`	Error	A command declares more than one concurrency block, and a command has at most one.
`PLAY0039`	Error	A line in a concurrency block names a dimension the block does not have.
`PLAY0040`	Error	A dimension of a concurrency block is not written the way that dimension is written.
`PLAY0041`	Error	A concurrency block states one dimension more than once.
`PLAY0042`	Error	A `produces` line is neither `produces <EventType>` nor `produces when <condition>`.
`PLAY0043`	Error	A `produces when` condition is followed by no event to produce.
`PLAY0044`	Error	A mapping line is not `<property> = <source>`.
`PLAY0045`	Error	A handler names neither a `file` nor an inline code block.
`PLAY0046`	Error	A line in a handler body opens with a word a handler declares nothing by.

Queries

Code	Severity	Reported when
`PLAY0047`	Error	A `query` line is not `query <Name> => [observable] <ReadModel>`.
`PLAY0048`	Error	A line in a query body opens with a word a query declares nothing by.
`PLAY0049`	Error	A `by` or `filter` parameter is not `<keyword> <name> <Type> [from <source>]`.
`PLAY0050`	Error	A `performer` line carries anything beyond the keyword.
`PLAY0051`	Error	A query declares more than one performer, and a query has at most one.
`PLAY0052`	Error	A performer names neither a `file` nor an inline code block.
`PLAY0053`	Error	A line in a performer body opens with a word a performer declares nothing by.

Projections

Code	Severity	Reported when
`PLAY0054`	Error	A projection document holds a top level line that does not open a `projection`.
`PLAY0055`	Error	A projection document declares no projection at all.
`PLAY0056`	Error	A `projection` line is not `projection <Name> [=> <ReadModel>]`.
`PLAY0057`	Error	A projection declares no directives, so it builds nothing.
`PLAY0058`	Error	A line in a projection body opens with a word a projection declares nothing by.
`PLAY0059`	Error	A projection declares more than one key.
`PLAY0060`	Error	A `from` block declares more than one key.
`PLAY0061`	Error	A `from` line names no event to read from.
`PLAY0062`	Error	An event reference is not a name the language can read as one.
`PLAY0063`	Error	A `join` line is not `join <property> on <key>`.
`PLAY0064`	Error	A join block holds a line that is not `with <EventType>`.
`PLAY0065`	Error	A `children` line is not `children <collection> identified by <key>`.
`PLAY0066`	Error	A `nested` line is not `nested <property>`.
`PLAY0067`	Error	A nested block reads from no event, so nothing ever fills it.
`PLAY0068`	Error	A `remove` line is neither `remove with <EventType>` nor `remove via join on <EventType>`.
`PLAY0069`	Error	A remove block holds a line other than `parent`.
`PLAY0070`	Error	A `clear` line is not `clear with <EventType>`.
`PLAY0071`	Error	`clear with` is written where there is nothing to clear.
`PLAY0072`	Error	A part of a composite key is not `<property> = <expression>`.
`PLAY0073`	Error	A composite key part is a template expression, which a key cannot be.
`PLAY0074`	Error	A composite key declares no parts.
`PLAY0075`	Error	A mapping line in a projection is not one the language can read.

Captures

Code	Severity	Reported when
`PLAY0076`	Error	A capture document holds a top level line that does not open a `capture`.
`PLAY0077`	Error	A capture document declares no capture at all.
`PLAY0078`	Error	A `capture` line is not `capture <Name>`.
`PLAY0079`	Error	A line in a capture body opens with a word a capture declares nothing by.
`PLAY0080`	Error	A map entry is not `<property> = <source> [translate]`.
`PLAY0081`	Error	A translation is not `"<source>" => <target>`.
`PLAY0082`	Error	A `split` line is not `split <property> by "<separator>"`.
`PLAY0083`	Error	A target of a split is not a property path.
`PLAY0084`	Error	An `append` line is not `append <EventType>`.
`PLAY0085`	Error	A line in an append body opens with a word an append declares nothing by.
`PLAY0086`	Error	A `when` line names no trigger.
`PLAY0087`	Error	A `when` clause is not one of the shapes a trigger is written in.
`PLAY0088`	Error	A value transition is not `when <Path> from <value> to <value>`.
`PLAY0089`	Error	A `when` clause combines properties with both `and` and `or`.
`PLAY0090`	Error	A `when` combinator is followed by no property.
`PLAY0091`	Error	A line in a children or nested block is neither `map` nor `append`.

Specifications

Code	Severity	Reported when
`PLAY0092`	Error	A specification document holds a top level line that does not open a `specification`.
`PLAY0093`	Error	A specification document declares no specification at all.
`PLAY0094`	Error	A `specification` line is not `specification <Name>`.
`PLAY0095`	Error	A line in a specification body opens with a word a specification declares nothing by.
`PLAY0096`	Error	A `when` line is not `when <CommandType>`.
`PLAY0097`	Error	A specification issues more than one command, and a specification is one example.
`PLAY0098`	Error	A `then error` line is neither `then error` nor `then error "<reason>"`.
`PLAY0099`	Error	A `given readmodel` or `then readmodel` line does not name a read model type.
`PLAY0100`	Error	A `given` or `then` line does not name an event type.
`PLAY0101`	Error	A value a specification step states is not `<property> = <value>`.

Screens

Code	Severity	Reported when
`PLAY0102`	Error	A `screen` line is not `screen <Name>`.
`PLAY0103`	Error	A line in a screen body opens with a word a screen declares nothing by.
`PLAY0104`	Error	A `data` line is not `data <ReadModel> via query <Query> [by <param>]`.
`PLAY0105`	Error	An `action` line is not `action <Command>`.
`PLAY0106`	Error	A line in an action body is neither `label` nor `navigate to`.
`PLAY0107`	Error	A navigation is not `navigate to <Screen> [by <param>]`.
`PLAY0108`	Error	A line under a screen layout does not name a slot.
`PLAY0109`	Error	A `title` line is not `title "<text>"`.
`PLAY0110`	Error	A line in a table body is neither `column` nor `on row-click navigate to`.
`PLAY0111`	Error	A line in a summary body is not `field <property> label "<text>"`.

Policies and authorization

Code	Severity	Reported when
`PLAY0112`	Error	A `policy` line is not `policy <Name>`.
`PLAY0113`	Error	A line in a policy body is neither `require` nor an inline code block.
`PLAY0114`	Error	A policy states nothing it requires of the caller.
`PLAY0115`	Error	A policy condition holds a token the language has no reading for.
`PLAY0116`	Error	A policy requirement states no condition.
`PLAY0117`	Error	A group opened in a policy condition is never closed.
`PLAY0118`	Error	A `role` requirement names no role.
`PLAY0119`	Error	A `claim` requirement names no claim.
`PLAY0120`	Error	A claim requirement does not say what the claim is matched against.
`PLAY0121`	Error	A claim match states nothing to match the claim to.
`PLAY0122`	Error	An `authorize` clause names no policy.
`PLAY0123`	Error	A policy is referred to by something that is not a policy name.

Authentication

Code	Severity	Reported when
`PLAY0124`	Error	An `authentication` line carries anything beyond the keyword.
`PLAY0125`	Error	A document declares more than one authentication block, and a document has at most one.
`PLAY0126`	Error	A `provider` line is not `provider <Name>`.
`PLAY0127`	Error	A setting of a provider is not `<name> <value>`.

Event seeding

Code	Severity	Reported when
`PLAY0128`	Error	A `seed` line carries anything beyond the keyword.
`PLAY0129`	Error	A seed group is not `for "<event source id>"`.
`PLAY0130`	Error	A line in a seed group does not name an event type.
`PLAY0131`	Error	A value a seeded event carries is not `<property> = <value>`.

Constraints

Code	Severity	Reported when
`PLAY0132`	Error	A `constraint` line is not `constraint <Name>`.
`PLAY0133`	Error	A constraint states nothing it holds the application to.
`PLAY0134`	Error	A line in a constraint body is not one the language can read.
`PLAY0135`	Error	A constraint states more than one rule, and a constraint states one.

Reactions

Code	Severity	Reported when
`PLAY0136`	Error	A `reaction` line is not `reaction <Name>`.
`PLAY0137`	Error	A line in a reaction body is not a trigger the language reads.
`PLAY0138`	Error	A reaction states no trigger, so nothing ever sets it off.
`PLAY0139`	Error	A line in a reaction trigger body opens with a word a trigger declares nothing by.

Validation rules

Code	Severity	Reported when
`PLAY0140`	Error	A `validate` line is neither `validate` nor `validate csharp`.
`PLAY0141`	Error	A validation rule is not one the language can read.
`PLAY0142`	Error	A validation rule names a rule the language does not have.
`PLAY0143`	Error	A `rule` line does not name the rule with an identifier.
`PLAY0144`	Error	A named rule names neither a `file` nor an inline code block.

Descriptions and tags

Code	Severity	Reported when
`PLAY0145`	Error	A `description` line is not `description "<text>"`.
`PLAY0146`	Error	A fenced description holds no text.
`PLAY0147`	Error	Something is described more than once, and a description is given once.
`PLAY0148`	Error	A `tag` line carries no value.
`PLAY0149`	Error	A tag value is neither an identifier, a string literal nor a context expression.

Expressions

Code	Severity	Reported when
`PLAY0150`	Error	A `literal` expression carries no value.
`PLAY0151`	Error	A $causedBy expression names a property the cause does not carry.
`PLAY0152`	Error	An expression is not one the language can read.
`PLAY0153`	Warning	A $context path opens with a root the context does not have.
`PLAY0154`	Warning	A $context.causedBy path names a property the cause does not carry.
`PLAY0155`	Warning	A $context.identity path names a property the identity does not carry.
`PLAY0156`	Error	A template expression is never closed.
`PLAY0157`	Error	An interpolation inside a template expression is never closed.

Conditions

Code	Severity	Reported when
`PLAY0158`	Error	A condition holds a token the language has no reading for.
`PLAY0159`	Error	A condition is expected and nothing is written.
`PLAY0160`	Error	A group opened in a condition is never closed.
`PLAY0161`	Error	A comparison states what is compared and not how.
`PLAY0162`	Error	A comparison states nothing to compare against.

Inline code

Code	Severity	Reported when
`PLAY0163`	Error	A construct opening an inline code block is followed by no fence.
`PLAY0164`	Error	An inline code block is never closed.

Names the document does not resolve

Code	Severity	Reported when
`PLAY0165`	Warning	A property names a type nothing in the document or its imports declares.
`PLAY0166`	Warning	An event is referred to that nothing in the document or its imports declares.
`PLAY0167`	Warning	A policy is referred to that nothing in the document declares.
`PLAY0168`	Error	A concept and a type, or two of either, are declared under one name.
`PLAY0169`	Error	An authentication block declares two providers under one name.
`PLAY0170`	Error	A seed block seeds nothing.
`PLAY0171`	Error	A concurrency block narrows nothing.

A folder compiled as one application

Code	Severity	Reported when
`PLAY0172`	Error	Two files of a folder each declare something the application has at most one of.
`PLAY0173`	Error	Two files of a folder declare the same name.
`PLAY0174`	Warning	Two files of a folder describe the same thing differently, and the first description is kept.

What a command reads to decide

Code	Severity	Reported when
`PLAY0175`	Error	A `reads` line is not `reads <ReadModel>` or `reads <ReadModel> by <property>`.
`PLAY0176`	Error	A command declares that it reads the same read model more than once.
`PLAY0177`	Warning	A command reads a read model no projection in the document produces.
`PLAY0178`	Warning	The `by` of a `reads` declaration does not name a property of the command.

Rules about the whole artifact

Code	Severity	Reported when
`PLAY0179`	Error	A `require` rule carries no condition.
`PLAY0180`	Error	The body of a `require` rule holds something other than its `message`.
`PLAY0181`	Warning	A `require` operand is qualified by something the command does not read.
`PLAY0182`	Warning	A `require` operand names neither a property of the artifact nor state it reads.

Authentication

Code	Severity	Reported when
`PLAY0183`	Error	An authentication provider carries a configuration body, which belongs where the application runs.

Authorize

Code	Severity	Reported when
`PLAY0184`	Error	Tokens are left over after the requirement of an `authorize`.
`PLAY0185`	Error	A parenthesised group in an `authorize` is never closed.

Read models and reducers

Code	Severity	Reported when
`PLAY0186`	Error	A `readmodel` line is not `readmodel <Name>`.
`PLAY0187`	Error	A `reducer` line is not `reducer <Name> => <ReadModel>`.
`PLAY0188`	Error	A line in a reducer body is not an `on <EventType>` rule.
`PLAY0189`	Error	A reducer declares no rule, so nothing it observes is stated.
`PLAY0190`	Error	The body of a reducer rule holds something other than a description, a file or inline code.
`PLAY0191`	Error	More than one projection or reducer builds the same read model.
`PLAY0192`	Error	A document declares the same read model more than once.

Where a produced event lands, and what a reaction sets off

Code	Severity	Reported when
`PLAY0193`	Error	A `produces` declares more than one `for`, and an event is appended to one event source.
`PLAY0194`	Error	An `invokes` line is not `invokes <Command>`.
`PLAY0195`	Warning	A reactor invokes a command the document does not declare.

What a screen binds to

Code	Severity	Reported when
`PLAY0196`	Warning	A screen binds data to a query nothing in scope declares.
`PLAY0197`	Warning	A screen navigates to a screen nothing in scope declares.
`PLAY0198`	Warning	A bare name matches more than one declaration at the same depth, so which one it means is undecided.

What a query's results are narrowed to

Code	Severity	Reported when
`PLAY0199`	Error	A `scoped` line is not `scoped to <scope>`.
`PLAY0200`	Error	A query declares more than one scope, and results are narrowed one way.

UI profiles

Code	Severity	Reported when
`PLAY0201`	Error	A `ui profile` line is not `ui profile <Name>`.
`PLAY0202`	Error	Two `ui profile` blocks in the same document declare the same name.
`PLAY0203`	Error	A `target` line under a `ui profile` is neither `target platform ...` nor `target size ...`.
`PLAY0204`	Error	A `ui profile` declares `target platform` or `target size` more than once.
`PLAY0205`	Error	A line under a `packages` block is not a valid package name.
`PLAY0206`	Error	A `ui profile`'s `packages` block lists the same package more than once.
`PLAY0207`	Error	A line in a `ui profile` body is not `target` or `packages`, or `packages` is declared more than once.

Forms

Code	Severity	Reported when
`PLAY0208`	Error	A `form` line is not `form <Name> for <Command>`.
`PLAY0209`	Error	Two `form` blocks in the same document declare the same name.
`PLAY0210`	Error	A line in a `form` body is not `populate`, `field` or `on submit`.
`PLAY0211`	Error	A `populate` line is neither `populate via query ...` nor `populate from item`.
`PLAY0212`	Error	A `form` declares `populate` more than once.
`PLAY0213`	Error	A `field` line is not `field <property> [from <source>\|compose using <Callback>] [label "..."]`.
`PLAY0214`	Error	An `on submit` line is not `on submit navigate to <Screen> [by <param>]`.
`PLAY0215`	Error	A `form` declares `on submit` more than once.
`PLAY0216`	Warning	A `field` binds to a property its form's command does not declare.

Contributions

Code	Severity	Reported when
`PLAY0217`	Error	A `contribute` line is not `contribute to <ContributionPoint>`.
`PLAY0218`	Error	A line in a `contribute to` body is not `navigate`, `label` or `order`.
`PLAY0219`	Error	A contribution declares `navigate to` more than once.
`PLAY0220`	Error	A contribution declares `label` more than once.
`PLAY0221`	Error	A contribution declares `order` more than once.
`PLAY0222`	Error	A contribution's `label` line is not `label "..."` or `label $strings....`.
`PLAY0223`	Error	A contribution's `order` line is not `order <number>`.
`PLAY0224`	Warning	A contribution names a contribution point nothing in scope declares.

Themes

Code	Severity	Reported when
`PLAY0225`	Error	A `theme` line is not `theme <Name>`.
`PLAY0226`	Error	Two `theme` blocks in the same document declare the same name.
`PLAY0227`	Error	A line in a `theme` body is not `compatible with <Package>`.
`PLAY0228`	Error	A `theme` declares compatibility with the same package more than once.
`PLAY0229`	Error	A `ui profile`'s `theme` line is not `theme <Name>`.
`PLAY0230`	Error	A `ui profile` declares `theme` more than once.
`PLAY0231`	Warning	A `ui profile` selects a theme nothing in the document declares.
`PLAY0232`	Warning	A `ui profile` selects a theme not declared compatible with one of the profile's own packages.

Arrangement

Code	Severity	Reported when
`PLAY0233`	Error	An `arrangement` line is not `arrangement flow` or `arrangement freeform`.
`PLAY0234`	Error	A layout, screen template or dialog template declares `arrangement` more than once.
`PLAY0235`	Error	A `row`, `column` or `grid` line in an arrangement is malformed.
`PLAY0236`	Error	A slot leaf within an arrangement tree has malformed sizing attributes.
`PLAY0237`	Error	A `when` override line in an arrangement is not a valid width/height size-class condition.
`PLAY0238`	Error	An arrangement declares more than one `when` override for the same width/height size-class combination.
`PLAY0239`	Error	An `arrangement` block's body does not match its mode - a `flow` arrangement declares a `variant`, or a `freeform` arrangement declares anything other than one.
`PLAY0240`	Error	A `variant` line is not `variant width <compact\|regular>, height <compact\|regular>`.
`PLAY0241`	Error	An arrangement declares more than one `variant` for the same width/height size-class combination.
`PLAY0242`	Error	A `place` line is not `place <Slot> hidden` or `place <Slot> at x,y size w,h`.
`PLAY0243`	Error	A `variant` places (or hides) the same slot more than once.
`PLAY0244`	Warning	A `freeform` arrangement's `variant` does not mention (place or hide) a slot another variant of the same arrangement places.

Triggers

Code	Severity	Reported when
`PLAY0245`	Error	A `trigger` line is not `trigger <Name>`.
`PLAY0246`	Error	A line in a trigger body is neither a description nor a value the trigger provides.
`PLAY0247`	Error	The document declares two triggers by the same name, leaving no answer to which one a reaction means.
`PLAY0248`	Warning	A `when` line names neither an event nor a trigger the document or the compiler knows.
`PLAY0249`	Error	An `every` line is not `every <n> <seconds\|minutes\|hours\|days>`.
`PLAY0250`	Error	An `at` line is not `at <HH:mm>`, optionally followed by `on <Weekday>` or `on day <n>`.
`PLAY0251`	Warning	A reaction takes a value from an occurrence that the trigger does not provide.
`PLAY0252`	Error	A reaction states more than one `where`, and a reaction is narrowed by one condition.
`PLAY0253`	Error	A reaction declares the same trigger more than once, so the second says nothing the first did not.

Layouts, screen templates and dialog templates

Code	Severity	Reported when
`PLAY0254`	Error	A `screen template` line is not `screen template <Name>`.
`PLAY0255`	Error	A `dialog template` line is not `dialog template <Name>`.
`PLAY0256`	Error	A `fits slot` line is not `fits slot <name>`.
`PLAY0257`	Error	A screen template declares `fits slot` more than once.
`PLAY0258`	Error	A layout or a dialog template declares `fits slot` - neither fills a slot of a parent structure.
`PLAY0259`	Error	A top level `layout` line is not `layout <Name>`.
`PLAY0260`	Error	A document declares more than one layout by the same name.
`PLAY0261`	Error	A `ui profile`'s `layout` line is not `layout <Name>`.
`PLAY0262`	Error	A `ui profile` declares `layout` more than once.
`PLAY0263`	Warning	A `ui profile` selects a layout nothing in the document declares.

File references

Code	Severity	Reported when
`PLAY0264`	Warning	A `file` directive names an absolute path, and a file reference is relative to the repository root.

A path that does not resolve is not a diagnostic, at any severity. A document is read in a designer, in a build and on a machine where the tree is not present, so the compiler never holds a path against a file system - a stale path must not be what makes a valid document invalid. A consumer that can resolve paths decides for itself what an unresolvable one means.

Specification query results

Code	Severity	Reported when
`PLAY0265`	Error	A `then query` line does not name a query.
`PLAY0266`	Error	A line in a `then query` body is neither `arguments` nor `result`.
`PLAY0267`	Error	A `then query` assertion declares `arguments` more than once.

Semantic binding

Code	Severity	Reported when
`PLAY0268`	Error	Source syntax carries portable behavior ESM v1 cannot represent, including a specification `for <value>` event-source assertion reserved for ESM v2.
`PLAY0269`	Information	Source syntax is explicitly deferred from the current backend semantic profile.
`PLAY0270`	Information	Source syntax is realization or operational metadata rather than portable behavior.
`PLAY0271`	Information or error	Source syntax keeps its legacy meaning and cannot be strengthened into ESM v1 implicitly.
`PLAY0272`	Error	Source syntax requires an explicit reviewed semantic migration before binding.
`PLAY0273`	Error	Syntax and identity information cannot produce a coherent semantic compilation.
`PLAY0274`	Error	A syntax location cannot be mapped to a supplied semantic source document.

Specification event-source assertions

Code	Severity	Reported when
`PLAY0275`	Error	A specification event-source assertion is a bare `for` and does not provide a value.
`PLAY0276`	Error	One specification command or event step declares its `for <value>` event-source assertion more than once.

Projection variants

Code	Severity	Reported when
`PLAY0277`	Error	A `variant` line is not `variant <Name>`.
`PLAY0278`	Error	A variant declares no `enters on` event, so nothing ever activates it.
`PLAY0279`	Error	An `enters on` line is not `enters on <EventType> [key <expression>]`.
`PLAY0280`	Error	A `variant` is declared inside another variant, and variants do not nest.
`PLAY0281`	Error	Two variants of the same projection declare the same name.

Model consistency

These errors are reported by ordinary compilation, including compilation of a folder as one application; semantic binding is not required. References resolve from the innermost scope outward. Unknown or ambiguous declarations and imported shapes are not guessed.

Code	Severity	Reported when
`PLAY0282`	Error	A declarative `validate` rule targets a field absent from the command's declared shape, including named rules with implementation blocks.
`PLAY0283`	Error	The type supplied by `reads <View> by <field>` is incompatible with every declared query `by` parameter of that view. Filter parameters do not substitute for a key. Parameter names may differ; distinct concepts remain distinct types.
`PLAY0284`	Error	A `children` or `nested` block never populates a declared element field through its identity, explicit mappings, inherited `every` mappings, nested blocks, joins, or compatible AutoMap. Coverage is across the block's events, not a requirement that every update event fill every field.
`PLAY0285`	Error	A specification's expected event contradicts every possible declared producer of its `when` command, using decidable literals, property copies and equality conditions.
`PLAY0286`	Error	A specification value is not a member of the enum declared by that specific command, event, read-model field or query parameter. Bare members, qualified members and quoted member names are accepted.
`PLAY0287`	Error	A command or reaction producer, a capture append mapping, or a specification's `given`/`then` event step, assigns a field absent from the referenced event's declaration.

These checks do not execute handlers, custom predicates or opaque expressions. An undeclared query signature does not establish a read-key mismatch. An unknown event shape under AutoMap, or an open all subscription with AutoMap, leaves projection coverage undecidable. Outcome checks compare explicit producer mappings only; they do not invent mappings for omitted fields.

The complete Program v1 disposition of current syntax is maintained as a delivery artifact alongside the Screenplay architecture and program.

AST authoring

Code	Severity	Reported when
`PLAY0288`	Information	An accepted AST authoring operation canonicalizes a touched document. Its formatting and comments may change; untouched documents retain their exact bytes.
`PLAY0289`	Error	An empty authoring workspace has no source documents to compile to an executable model. You can still propose its first typed document.

Source-authoring acceptance and executable readiness are separate verdicts. An authoring proposal validates the complete .play application and identity continuity without claiming that every language construct is supported by the executable backend profile. Executable-only workspace transactions remain strict.

Retired codes

None yet. When a code is retired it is listed here with the release it went in, and its number stays out of use forever.