processContext

SUPPORT · function · Runtime value

Run a complete context policy in one call: snapshot, execute and finalize.

Import

TypeScript

import { processContext } from '@jangts/agent-core/support';

JavaScript

import { processContext } from '@jangts/agent-core/support';

Other public entry points:@jangts/agent-core/support, @jangts/agent-core/support/context.

Definition

Call

processContext(plan: ContextPlan, policy: ContextPolicy, ports: ProcessingPorts): Promise<{ context: BuiltContext; report: ContextProcessingReport; }>

Run a complete context policy in one call: snapshot, execute and finalize.

Parameter	Type	Passing	Description
plan	ContextPlan	Required	—
policy	ContextPolicy	Required	—
ports	ContextProcessingOptions	Required	—

Fields of plan

Field	Type	Required	Description
fragments	readonly ContextFragment[]	Required	Read-only. Fragments in the order supplied by the App; assembly preserves it.
maxInputChars	number	Required	Character budget Core validates after assembly.
additionalMessages	readonly (ModelMessage & { role: "user"; })[] | undefined	Optional	Protected user messages (for example image inputs); text counts toward the same budget.
originalFragments	readonly ContextFragment[] | undefined	Optional	Trusted originals for structural mutation auditing; never sent to the model.
mutableFragmentIds	readonly string[] | undefined	Optional	Explicit value-mutation allowance when originals are supplied.

Fields of ports

Field	Type	Required	Description
stageId	string	Required	Read-only. Stage the processing belongs to; reported in diagnostics and selection calls.
compressors	readonly ContextCompressor[]	Required	Read-only. Compressors available by handler id.
selectors	readonly ContextSelector[] | undefined	Optional	Read-only. Selectors available by handler id; required only for model selection.
callModel	ContextModelCall	Required	Read-only. See the type definition and usage context.
remainingCalls	(() => number) | undefined	Optional	Read-only. Remaining model calls; used to reject unaffordable selections.
tokenBudget	ContextTokenMeasurement | undefined	Optional	Read-only. Token measurement; without it, token triggers and targets cannot apply.
logger	SubFlowLog | undefined	Optional	Read-only. Explicit optional recorder for this operation; never inferred from diagnostics.
signal	AbortSignal	Required	Read-only. Non-optional cancellation signal; never undefined once execution has started.
diagnostics	DiagnosticContext | undefined	Optional	Read-only. Diagnostic scope of the enclosing call, when recording is enabled.

Optional shapes of Parameter policy: choose one shape; required fields for each branch are listed separately.

Branch 1

Field	Type	Required	Description
mode	"validate"	Required	See the type definition and usage context.

Branch 2

Field	Type	Required	Description
mode	"reduce"	Required	See the type definition and usage context.
triggerChars	number | undefined	Optional	See the type definition and usage context.
targetInputChars	number | undefined	Optional	See the type definition and usage context.
triggerTokens	number | undefined	Optional	See the type definition and usage context.
targetInputTokens	number | undefined	Optional	See the type definition and usage context.
selection	ContextSelection | undefined	Optional	See the type definition and usage context.
steps	readonly ContextReduction[]	Required	See the type definition and usage context.

Branch 3

Field	Type	Required	Description
mode	"audit"	Required	See the type definition and usage context.
mutableFragmentIds	readonly string[]	Required	See the type definition and usage context.

Returns: Promise<{ context: BuiltContext; report: ContextProcessingReport; }>.

Awaited value: { context: BuiltContext; report: ContextProcessingReport; }.

Return value structure

Field	Type	Required	Description
context	BuiltContext	Required	See the type definition and usage context.
report	ContextProcessingReport	Required	See the type definition and usage context.

Examples

• Context policy: validate, reduce, and audit: Support provides replaceable policy implementations while Core keeps the final input contract and budget checks.

Explicitly use a validation-only policy

Beginner · Node.js

TypeScript

import { Support } from '@jangts/agent-core';
import type { ContextPolicy } from '@jangts/agent-core/support/context';
const policy: ContextPolicy = { mode: 'validate' };
Support.validateContextPolicy(policy, [], []);
console.log(policy.mode);

JavaScript

import { Support } from '@jangts/agent-core';
const policy = { mode: 'validate' };
Support.validateContextPolicy(policy, [], []);
console.log(policy.mode);

Configure reduction order from real business fragments

Configuration · Node.js

These numbers are explicit choices for the example business, not SDK recommendations for capacities that suit all models.

TypeScript

import { Support } from '@jangts/agent-core';
import type { ContextPolicy } from '@jangts/agent-core/support/context';
const policy: ContextPolicy = { mode: 'reduce', triggerChars: 1800, targetInputChars: 1500,
  selection: { mode: 'sequence' },
  steps: [{ id: 'recent-history', kind: 'trim', fragmentId: 'history', field: 'messages',
    grouping: { kind: 'user-turn' }, keepGroups: 2, targetChars: 1000 }],
};
Support.validateContextPolicy(policy, [], []);
console.log(policy.steps);

JavaScript

import { Support } from '@jangts/agent-core';
const policy = { mode: 'reduce', triggerChars: 1800, targetInputChars: 1500,
    selection: { mode: 'sequence' },
    steps: [{ id: 'recent-history', kind: 'trim', fragmentId: 'history', field: 'messages',
            grouping: { kind: 'user-turn' }, keepGroups: 2, targetChars: 1000 }],
};
Support.validateContextPolicy(policy, [], []);
console.log(policy.steps);

Limit the mutable range for the App's own processing

Extension · Node.js

Auditing also requires the ContextPlan to carry the original fragments; listing IDs alone does not modify or publish material by itself.

TypeScript

import { Support } from '@jangts/agent-core';
import type { ContextPolicy } from '@jangts/agent-core/support/context';
const policy: ContextPolicy = { mode: 'audit', mutableFragmentIds: ['history'] };
Support.validateContextPolicy(policy, [], []);
console.log(policy.mutableFragmentIds);

JavaScript

import { Support } from '@jangts/agent-core';
const policy = { mode: 'audit', mutableFragmentIds: ['history'] };
Support.validateContextPolicy(policy, [], []);
console.log(policy.mutableFragmentIds);

Related policy source

• Real scheduling catalog for policies and reduction operations

Related definitions

• BuiltContext
• ContextPlan
• ContextPolicy
• ContextProcessingOptions
• ContextProcessingReport