Kernel reference

Handwritten from src/PSLoom/PSLoom.psd1, Cmdlets, Verbs and runtime exception classes in PSLoom/PSLoom. Cmdlets appear in manifest order. Positions are zero-based; named means no positional binding. Common PowerShell parameters are omitted. SwitchParameter values are switches; ? denotes a nullable .NET value.

Cmdlets

Invoke-Loom

Provisions harnesses, validates and executes a draft once per session, then raises SessionStarting.

Name	Type	Position	Mandatory	Description
Draft	ScriptBlock	0	Yes	The complete draft.
Validate	SwitchParameter	named	No	Import installed harnesses and validate; no execution or installation.
Reweave	SwitchParameter	named	No	Reapply an edited draft in an already woven session.

Invoke-Loom -Draft { Style ':example:*' enabled $true }

Prepass/provisioning/scope errors block execution. Verb failures are collected and written once as non-terminating errors. An ordinary terminating PowerShell statement can end the draft; verb isolation does not make arbitrary scripts transactional.

Measure-Loom

Reports the last draft's phase and verb timings, plus staged-application timings.

Name	Type	Position	Mandatory	Description
GroupBy	Grouping	0	No	None (default), Harness, or Verb; grouping aggregates only verb rows.

Measure-Loom -GroupBy Harness

Get-Shed

Lists staged statements, their timing, state, duration and failures.

Name	Type	Position	Mandatory	Description
State	ShedState[]	0	No	Filter by Pending, Armed, Applied, Skipped, Failed, Superseded; omitted means all.

Get-Shed -State Failed,Pending

Armed is reserved for on-demand application, which is not implemented.

Update-Harness

Updates installed first-party harness modules from PSGallery for the next session.

Name	Type	Position	Mandatory	Description
Name	string[]	0	No	Harness names; omitted means every installed first-party harness.

Supports -WhatIf and -Confirm. Does not install absent harnesses.

Update-Harness Reed -WhatIf

Register-Hook

Registers a script handler and wires its hook kind on first use.

Name	Type	Position	Mandatory	Description
Kind	HookKind	0	Yes	Hook kind from the guide.
Action	ScriptBlock	1	Yes	Receives HookInvocation as $_ and first argument.
Name	string	named	No	Same kind/name replaces its prior registration.

Register-Hook PrePrompt { $global:lastPrompt = Get-Date } -Name clock

Unregister-Hook

Removes a registration by identifier or kind/name; wiring stays installed.

Name	Type	Position	Mandatory	Description
Id	Guid	0	Yes, ById	Default parameter set; binds pipeline property Id.
Kind	HookKind	named	Yes, ByName	Kind of the named registration.
Name	string	named	Yes, ByName	Name of the registration.

Unregister-Hook -Kind PrePrompt -Name clock

Get-Hook

Lists registrations in registration order, optionally filtered by kind and case-insensitive name.

Name	Type	Position	Mandatory	Description
Kind	HookKind?	0	No	Kind filter.
Name	string	named	No	Registration name filter.

Get-Hook PrePrompt

Trace-Hook

Lists recent invocations oldest first, including duration, slow flag and exception.

Name	Type	Position	Mandatory	Description
Last	int?	0	No	Most recent count, zero or greater; omitted returns all retained entries.

Trace-Hook -Last 10

Set-Style

Defines or replaces a style value for a context pattern, then runs affected watchers.

Name	Type	Position	Mandatory	Description
Context	string	0	Yes	Case-sensitive PowerShell wildcard pattern.
Name	string	1	Yes	Style name.
Value	object?	2	Yes	Allows null, empty string and empty collection.

Set-Style ':example:*' enabled $true

Get-Style

Resolves a style for a concrete context, writing nothing when no pattern matches unless a default was supplied.

Name	Type	Position	Mandatory	Description
Context	string	0	Yes	Concrete context.
Name	string	1	Yes	Style name.
Default	object?	named	No	Value when no definition resolves; allows null.

Get-Style ':example:git' enabled -Default $false

Test-Style

Tests whether a resolved value means enabled.

Name	Type	Position	Mandatory	Description
Context	string	0	Yes	Concrete context.
Name	string	1	Yes	Style name.

True values include boolean true, nonzero integers, and strings true, yes, 1, on, enabled.

Test-Style ':example:git' enabled

Remove-Style

Removes an exact stored context-pattern/name pair and runs affected watchers.

Name	Type	Position	Mandatory	Description
Context	string	0	Yes	Exact stored pattern; binds pipeline property.
Name	string	1	Yes	Style name; binds pipeline property.

Remove-Style ':example:*' enabled

Get-StyleDefinition

Lists stored definitions in definition order, without resolving a winning pattern.

Name	Type	Position	Mandatory	Description
Context	string	0	No	Exact stored context-pattern filter.
Name	string	1	No	Name filter.

Get-StyleDefinition -Name enabled

Register-StyleWatcher

Registers a script receiving StyleChange as $_ and its first argument.

Name	Type	Position	Mandatory	Description
Context	string	0	Yes	Concrete context, or pattern with -Pattern.
Name	string	1	Yes	Style name.
Action	ScriptBlock	2	Yes	Handler after committed writes.
Pattern	SwitchParameter	named	No	Observe every matching written context pattern.
Replay	SwitchParameter	named	No	Immediately replay resolved value, or each matching stored definition in pattern mode.

$watcher = Register-StyleWatcher ':example:git' enabled { param($change) $global:lastStyleChange = $change } -Replay

Unregister-StyleWatcher

Removes a style watcher by registration identifier.

Name	Type	Position	Mandatory	Description
Id	Guid	0	Yes	Watcher identifier; binds pipeline property Id.

$watcher | Unregister-StyleWatcher

Trace-Style

Lists recent watcher runs oldest first, with duration and exception.

Name	Type	Position	Mandatory	Description
Last	int?	0	No	Most recent count, zero or greater; omitted returns all retained entries.

Trace-Style -Last 10

New-Treadle

Defines a global function that invokes a command with baked arguments followed by caller arguments.

Name	Type	Position	Mandatory	Description
Name	string	0	Yes	Nonempty treadle name.
Command	object	1	Yes	Non-null string or script block containing one constant command.
Force	SwitchParameter	named	No	Replace a colliding command.
PassThru	SwitchParameter	named	No	Emit the TreadleDefinition.

New-Treadle glog { git log --oneline } -PassThru

Get-Treadle

Lists all treadles or those matching supplied names.

Name	Type	Position	Mandatory	Description
Name	string[]	0	No	Case-insensitive names or wildcard patterns.

Get-Treadle 'g*'

Remove-Treadle

Removes treadles and their installed functions while leaving unrelated same-named commands alone.

Name	Type	Position	Mandatory	Description
Name	string[]	0	Yes	Nonempty names; accepts pipeline values and properties.

Remove-Treadle glog

Draft verbs

These are scoped vocabulary, not exported cmdlets. All three are valid in DraftScope; none opens a nested scope.

Thread

Declares a first-party harness for provisioning before execution. Reweave behavior: Additive; key: Name.

Name	Type	Position	Mandatory	Description
Name	string	0	Yes	Top-level literal harness name.
Version	Version?	named	No	Literal pinned module version.

Invoke-Loom { Thread Reed }

Style

Defines a style as Set-Style does. Reweave behavior: Replay; keys: Context, Name; removed definitions can be reverted.

Name	Type	Position	Mandatory	Description
Context	string	0	Yes	Context pattern.
Name	string	1	Yes	Style name.
Value	object?	2	Yes	Allows null, empty string and empty collection.

Invoke-Loom { Style ':example:*' enabled $true }

Treadle

Defines a shortcut as New-Treadle does, without a force switch. Reweave behavior: Replay; key: Name; removal can be reverted.

Name	Type	Position	Mandatory	Description
Name	string	0	Yes	Treadle name.
Body	ScriptBlock	1	Yes	Single constant command template; not an [OpensScope] body.

Invoke-Loom { Treadle glog { git log --oneline } }

Shed

The kernel parses this top-level modifier before execution; it is not a [LoomVerb] class and does not accept ordinary cmdlet common parameters. It applies to the next statement. No positional arguments and no modifiers are mandatory.

Name	Type	Position	Mandatory	Description
Wait	switch	named	No	Queue in default slot 0a.
Slot	literal string	named	No	Queue in numeric slot plus a, b or c, e.g. '1b'.
OnDemand	switch	named	No	Reserved; currently rejected for every statement.
LoadIf	ScriptBlock	named	No	Evaluate a condition at application time.
RequiresCommand	literal string	named	No	Require a discoverable command at application time.
Lucid	switch	named	No	Suppress success output.
Silent	switch	named	No	Suppress the deferred failure summary warning at the prompt.
AtLoad	ScriptBlock	named	No	Run after successful application.

Invoke-Loom {
    Shed -Wait -Lucid
    Get-Date
}
Get-Shed

Only one of Wait, Slot, OnDemand is permitted. It cannot precede Thread, another Shed, or the end of a draft. See sheds.

Error ids

Runtime exceptions use the following identifiers. PowerShell may append the cmdlet's type to FullyQualifiedErrorId. LOOM_REWEAVE_REQUIRES_RESTART is warning text rather than an exception.

Id	Raised when
LOOM_NO_RUNSPACE	No current runspace exists.
LOOM_NO_ENGINE	Engine intrinsics are unavailable.
LOOM_HARNESS_NAME_INVALID	A harness name is not a letter followed by letters/digits.
LOOM_HARNESS_DUPLICATE	Another type already owns the harness name.
LOOM_HARNESS_COMPOSE_FAILED	Harness composition throws; registrations are rolled back.
LOOM_HARNESS_NOT_COMPOSED	A harness is requested before composition.
LOOM_HARNESS_NOT_INSTALLED	Required module/version is absent when it cannot be installed.
LOOM_HARNESS_IMPORT_FAILED	Module import fails.
LOOM_NOT_A_HARNESS	Imported module did not register the expected harness.
LOOM_API_DUPLICATE	Another harness already published the API type.
LOOM_VERB_ATTRIBUTE_MISSING	Registered verb lacks [LoomVerb].
LOOM_VERB_NAME_INVALID	Invalid DSL verb identifier.
LOOM_VERB_NO_SCOPE	Verb attribute lists no scope.
LOOM_VERB_DUPLICATE	Name already registered in a scope.
LOOM_VERB_OUT_OF_SCOPE	Verb is used outside its allowed scopes.
LOOM_THREAD_NOT_TOP_LEVEL	Thread is nested.
LOOM_THREAD_NAME_NOT_LITERAL	Thread name is computed.
LOOM_THREAD_NOT_PREPARED	Harness was not loaded before execution.
LOOM_DRAFT_STATEMENT_FAILED	Statement failure has no more specific PowerShell error record.
LOOM_HARNESS_NOT_FIRST_PARTY	Thread/update names a harness outside the allowlist.
LOOM_HARNESS_INSTALL_FAILED	Missing module cannot be installed.
LOOM_HARNESS_UPDATE_FAILED	Explicit update fails.
LOOM_HARNESS_VERSION_CONFLICT	Requested harness version differs from the loaded version.
LOOM_THREAD_VERSION_NOT_LITERAL	Version is not a valid literal.
LOOM_THREAD_VERSION_CONFLICT	Duplicate thread declarations request differing versions.
LOOM_REWEAVE_REQUIRES_RESTART	Removed invocation cannot be reverted (warning).
LOOM_REWEAVE_REVERT_FAILED	Reverting a removed invocation fails.
LOOM_SHED_NOT_TOP_LEVEL	Shed is nested.
LOOM_SHED_DANGLING	No statement follows Shed.
LOOM_SHED_STACKED	Two Shed statements occur consecutively.
LOOM_SHED_NOT_LITERAL	Modifier value has the wrong literal/script-block form.
LOOM_SHED_TIMING_CONFLICT	Multiple timing modifiers are supplied.
LOOM_SHED_NOT_ON_DEMAND	Target does not support on-demand application (all current targets).
LOOM_SHED_NOT_APPLICABLE	Target cannot be staged, such as Thread.
LOOM_SHED_UNKNOWN_MODIFIER	Modifier is unknown or ambiguous.
LOOM_SHED_APPLY_FAILED	Staged application fails outside a more specific error channel.
STYLE_INVALID_KEY	Empty context or style name.
STYLE_WATCHER_RECURSION	Watcher nesting exceeds the limit.
STYLE_WATCHER_FAILED	Watcher throws after a committed write.
HOOK_WIRING_FAILED	Wiring a hook kind fails.
HOOK_UNKNOWN_KIND	Invalid hook enum value.
HOOK_HANDLER_FAILED	Hook handler throws.
TREADLE_BODY_NOT_SINGLE_COMMAND	Body contains nonconstant arguments or is not one command.
TREADLE_NAME_COLLISION	Existing command collides without -Force.
TREADLE_INVALID_NAME	Name contains unsupported characters.
TREADLE_SUBSCRIBER_FAILED	Catalog subscriber fails after a change.

The contract assembly can additionally report these identifiers during kernel/harness use:

Id	Raised when
WARP_CONTRACT_MISMATCH	Harness lacks a Warp reference or targets another contract major.
WARP_HARNESS_ATTRIBUTE_MISSING	Harness type lacks [Harness].
WARP_KERNEL_UNAVAILABLE	No kernel is attached.
WARP_KERNEL_ALREADY_ATTACHED	A different kernel is already attached to the process.
WARP_FRAME_MISSING	Required enclosing DSL frame is absent.
WARP_VERB_OUTSIDE_LOOM	A verb runs outside a loom/DSL invocation.
WARP_VERB_UNHANDLED_EXCEPTION	Verb throws an exception without a more specific contract error.
WARP_SCOPE_INVALID	Referenced scope type does not satisfy DSL scope rules.
CREEL_PATH_ESCAPE	Storage path is rooted, invalid, escapes the root or crosses an escaping link.