feat(sdk): reduce context prompt sizes with truncation and cache-friendly ordering (#1615)

* chore: add v1.31.0 npm known-issue notice to issue template config

Adds a top-priority contact link to the issue template chooser so users
are redirected to the Discussions announcement before opening a duplicate
issue about v1.31.0 not being on npm.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

* feat(sdk): reduce context prompt sizes with truncation and cache-friendly ordering (#1614)

- Reorder prompt assembly in PromptFactory to place stable content (role,
  workflow, phase instructions) before variable content (.planning/ files),
  enabling Anthropic prompt caching at 0.1x input cost on cache hits
- Add markdown-aware truncation for oversized context files (headings +
  first paragraphs preserved, rest omitted with line counts)
- Add ROADMAP.md milestone extraction to inject only the current milestone
  instead of the full roadmap
- Export truncation utilities from SDK public API
- 60 new + updated tests covering truncation, milestone extraction,
  cache-friendly ordering, and ContextEngine integration

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

---------

Co-authored-by: Claude Sonnet 4.6 <noreply@anthropic.com>
This commit is contained in:
Tom Boucher
2026-04-03 14:07:04 -04:00
committed by GitHub
parent 46d9c26158
commit 6d24b597a0
8 changed files with 554 additions and 7 deletions

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@@ -1,5 +1,8 @@
blank_issues_enabled: false
contact_links:
- name: "⚠️ v1.31.0 not on npm yet (known issue — workaround inside)"
url: https://github.com/gsd-build/get-shit-done/discussions
about: v1.31.0 was not published to npm due to a hardware failure. Read the pinned announcement for the workaround before opening an issue.
- name: Discord Community
url: https://discord.gg/gsd
about: Ask questions and get help from the community

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@@ -184,6 +184,90 @@ describe('ContextEngine', () => {
});
});
describe('context truncation', () => {
it('truncates files exceeding maxContentLength', async () => {
const largeContent = Array.from({ length: 100 }, (_, i) =>
`## Section ${i}\n\nFirst paragraph.\n\nLong detail ${'x'.repeat(200)}.`
).join('\n\n');
await createPlanningDir(projectDir, {
'STATE.md': '# State',
'ROADMAP.md': '# Roadmap',
'CONTEXT.md': largeContent,
});
const engine = new ContextEngine(projectDir, undefined, { maxContentLength: 500 });
const files = await engine.resolveContextFiles(PhaseType.Plan);
// CONTEXT.md should be truncated
expect(files.context!.length).toBeLessThan(largeContent.length);
expect(files.context).toContain('[...');
});
it('does not truncate files below threshold', async () => {
await createPlanningDir(projectDir, {
'STATE.md': '# State\nproject: test',
'ROADMAP.md': '# Roadmap\nphase 01',
'CONTEXT.md': '# Context\nstack: node',
});
const engine = new ContextEngine(projectDir);
const files = await engine.resolveContextFiles(PhaseType.Plan);
expect(files.context).toBe('# Context\nstack: node');
});
it('never truncates STATE.md (not in truncatable list)', async () => {
const largeState = `# State\n\n${'x'.repeat(20000)}`;
await createPlanningDir(projectDir, {
'STATE.md': largeState,
});
const engine = new ContextEngine(projectDir, undefined, { maxContentLength: 100 });
const files = await engine.resolveContextFiles(PhaseType.Execute);
expect(files.state).toBe(largeState);
});
it('extracts current milestone from ROADMAP.md when state is available', async () => {
const roadmap = `# Roadmap
## Milestone 1: Setup
### Phase 01
Setup content.
## Milestone 2: Build
### Phase 02
Build content.`;
await createPlanningDir(projectDir, {
'STATE.md': 'Current Milestone: Build',
'ROADMAP.md': roadmap,
'CONTEXT.md': '# Context',
});
const engine = new ContextEngine(projectDir);
const files = await engine.resolveContextFiles(PhaseType.Plan);
expect(files.roadmap).toContain('## Milestone 2: Build');
expect(files.roadmap).not.toContain('### Phase 01');
});
it('respects custom truncation options', async () => {
const content = '## Heading\n\nParagraph.\n\nMore.\n' + 'x'.repeat(500);
await createPlanningDir(projectDir, {
'STATE.md': '# State',
'ROADMAP.md': '# Roadmap',
'CONTEXT.md': content,
});
// Low threshold forces truncation
const engine = new ContextEngine(projectDir, undefined, { maxContentLength: 50 });
const files = await engine.resolveContextFiles(PhaseType.Plan);
expect(files.context!.length).toBeLessThan(content.length);
});
});
describe('PHASE_FILE_MANIFEST', () => {
it('covers all phase types', () => {
for (const phase of Object.values(PhaseType)) {

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@@ -5,6 +5,11 @@
* only needs STATE.md + config.json (minimal). Research needs STATE.md +
* ROADMAP.md + CONTEXT.md. Plan needs all files. Verify needs STATE.md +
* ROADMAP.md + REQUIREMENTS.md + PLAN/SUMMARY files.
*
* Context reduction (issue #1614):
* - Large files are truncated to keep prompts cache-friendly
* - ROADMAP.md is narrowed to the current milestone when possible
* - Truncation preserves headings + first paragraph per section
*/
import { readFile, access } from 'node:fs/promises';
@@ -14,6 +19,12 @@ import { constants } from 'node:fs';
import type { ContextFiles } from './types.js';
import { PhaseType } from './types.js';
import type { GSDLogger } from './logger.js';
import {
truncateMarkdown,
extractCurrentMilestone,
DEFAULT_TRUNCATION_OPTIONS,
type TruncationOptions,
} from './context-truncation.js';
// ─── File manifest per phase ─────────────────────────────────────────────────
@@ -64,16 +75,21 @@ const PHASE_FILE_MANIFEST: Record<PhaseType, FileSpec[]> = {
export class ContextEngine {
private readonly planningDir: string;
private readonly logger?: GSDLogger;
private readonly truncation: TruncationOptions;
constructor(projectDir: string, logger?: GSDLogger) {
constructor(projectDir: string, logger?: GSDLogger, truncation?: Partial<TruncationOptions>) {
this.planningDir = join(projectDir, '.planning');
this.logger = logger;
this.truncation = { ...DEFAULT_TRUNCATION_OPTIONS, ...truncation };
}
/**
* Resolve context files appropriate for the given phase type.
* Reads each file defined in the phase manifest, returning undefined
* for missing optional files and warning for missing required files.
*
* Files exceeding the truncation threshold are reduced to headings +
* first paragraphs. ROADMAP.md is narrowed to the current milestone.
*/
async resolveContextFiles(phaseType: PhaseType): Promise<ContextFiles> {
const manifest = PHASE_FILE_MANIFEST[phaseType];
@@ -94,6 +110,40 @@ export class ContextEngine {
}
}
// Apply context reduction: milestone extraction then truncation
if (result.roadmap && result.state) {
const before = result.roadmap.length;
result.roadmap = extractCurrentMilestone(result.roadmap, result.state);
if (result.roadmap.length < before) {
this.logger?.debug?.('ROADMAP.md narrowed to current milestone', {
before,
after: result.roadmap.length,
});
}
}
// Truncate oversized files (skip config.json — structured data, not markdown)
const truncatable: Array<{ key: keyof ContextFiles; filename: string }> = [
{ key: 'roadmap', filename: 'ROADMAP.md' },
{ key: 'context', filename: 'CONTEXT.md' },
{ key: 'research', filename: 'RESEARCH.md' },
{ key: 'requirements', filename: 'REQUIREMENTS.md' },
{ key: 'plan', filename: 'PLAN.md' },
{ key: 'summary', filename: 'SUMMARY.md' },
];
for (const { key, filename } of truncatable) {
const raw = result[key];
if (raw && raw.length > this.truncation.maxContentLength) {
const before = raw.length;
result[key] = truncateMarkdown(raw, filename, this.truncation);
this.logger?.debug?.(`${filename} truncated`, {
before,
after: result[key]!.length,
});
}
}
return result;
}

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@@ -0,0 +1,163 @@
import { describe, it, expect } from 'vitest';
import {
truncateMarkdown,
extractCurrentMilestone,
DEFAULT_TRUNCATION_OPTIONS,
} from './context-truncation.js';
// ─── truncateMarkdown ───────────────────────────────────────────────────────
describe('truncateMarkdown', () => {
it('returns content unchanged when below threshold', () => {
const content = '# Title\n\nShort content.';
const result = truncateMarkdown(content, 'TEST.md');
expect(result).toBe(content);
});
it('truncates content above threshold, keeping headings and first paragraphs', () => {
const sections = [];
for (let i = 0; i < 20; i++) {
sections.push(`## Section ${i}\n\nFirst paragraph of section ${i}.\n\nSecond paragraph with lots of detail.\nMore detail here.\nEven more detail.`);
}
const content = `# Title\n\n${sections.join('\n\n')}`;
const result = truncateMarkdown(content, 'BIG.md', { maxContentLength: 100 });
// Headings preserved
expect(result).toContain('# Title');
expect(result).toContain('## Section 0');
expect(result).toContain('## Section 19');
// First paragraphs preserved
expect(result).toContain('First paragraph of section 0.');
expect(result).toContain('First paragraph of section 19.');
// Second paragraphs omitted
expect(result).not.toContain('Second paragraph');
expect(result).not.toContain('More detail here.');
// Truncation markers present
expect(result).toContain('[...');
expect(result).toContain('lines omitted]');
expect(result).toContain('[Truncated: read .planning/BIG.md for full content]');
});
it('preserves YAML frontmatter entirely', () => {
const content = `---\nphase: "01"\nstatus: active\n---\n\n# Title\n\nParagraph 1.\n\nParagraph 2.\n${'x'.repeat(10000)}`;
const result = truncateMarkdown(content, 'STATE.md', { maxContentLength: 100 });
expect(result).toContain('---\nphase: "01"\nstatus: active\n---');
expect(result).toContain('# Title');
expect(result).toContain('Paragraph 1.');
});
it('is smaller than original when truncated', () => {
const longContent = Array.from({ length: 200 }, (_, i) =>
`## Section ${i}\n\nFirst paragraph.\n\nLong detail paragraph ${'x'.repeat(100)}.`
).join('\n\n');
const result = truncateMarkdown(longContent, 'HUGE.md', { maxContentLength: 100 });
expect(result.length).toBeLessThan(longContent.length);
});
it('handles content with no headings', () => {
const content = `First line.\n\nSecond paragraph.\n\nThird paragraph.\n${'x'.repeat(10000)}`;
const result = truncateMarkdown(content, 'FLAT.md', { maxContentLength: 100 });
// Should still truncate — first paragraph kept
expect(result).toContain('First line.');
expect(result.length).toBeLessThan(content.length);
});
it('default threshold is 8192 characters', () => {
expect(DEFAULT_TRUNCATION_OPTIONS.maxContentLength).toBe(8192);
});
});
// ─── extractCurrentMilestone ────────────────────────────────────────────────
describe('extractCurrentMilestone', () => {
const makeRoadmap = () => `# Project Roadmap
## Milestone 1: Foundation
### Phase 01: Setup
Requirements for setup.
### Phase 02: Core
Requirements for core.
## Milestone 2: Features
### Phase 03: Auth
Requirements for auth.
### Phase 04: API
Requirements for API.
## Milestone 3: Polish
### Phase 05: UI
Requirements for UI.`;
it('returns full roadmap when no state provided', () => {
const roadmap = makeRoadmap();
expect(extractCurrentMilestone(roadmap)).toBe(roadmap);
});
it('returns full roadmap when milestone not found in state', () => {
const roadmap = makeRoadmap();
const state = '# State\nstatus: active';
expect(extractCurrentMilestone(roadmap, state)).toBe(roadmap);
});
it('extracts current milestone section by name', () => {
const roadmap = makeRoadmap();
const state = 'Current Milestone: Features';
const result = extractCurrentMilestone(roadmap, state);
expect(result).toContain('## Milestone 2: Features');
expect(result).toContain('### Phase 03: Auth');
expect(result).toContain('### Phase 04: API');
// Other milestones omitted
expect(result).not.toContain('### Phase 01: Setup');
expect(result).not.toContain('### Phase 05: UI');
expect(result).toContain('other milestone(s) omitted');
});
it('matches milestone name case-insensitively', () => {
const roadmap = makeRoadmap();
const state = 'current milestone: features';
const result = extractCurrentMilestone(roadmap, state);
expect(result).toContain('## Milestone 2: Features');
expect(result).not.toContain('### Phase 01: Setup');
});
it('matches milestone from "milestone:" field in state', () => {
const roadmap = makeRoadmap();
const state = '# State\nmilestone: Foundation\nphase: 01';
const result = extractCurrentMilestone(roadmap, state);
expect(result).toContain('## Milestone 1: Foundation');
expect(result).toContain('### Phase 01: Setup');
expect(result).not.toContain('### Phase 03: Auth');
});
it('matches milestone from Current Position block', () => {
const roadmap = makeRoadmap();
const state = `# State
## Current Position
milestone: Polish
phase: 05`;
const result = extractCurrentMilestone(roadmap, state);
expect(result).toContain('## Milestone 3: Polish');
expect(result).toContain('### Phase 05: UI');
expect(result).not.toContain('### Phase 01: Setup');
});
it('preserves roadmap title in output', () => {
const roadmap = makeRoadmap();
const state = 'Current Milestone: Features';
const result = extractCurrentMilestone(roadmap, state);
expect(result).toContain('# Project Roadmap');
});
});

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@@ -0,0 +1,233 @@
/**
* Context truncation — reduces large .planning/ files to cache-friendly sizes.
*
* Two strategies:
* 1. Markdown-aware truncation: keeps headings + first paragraph per section,
* replaces the rest with a pointer to the full file.
* 2. Milestone extraction: pulls only the current milestone from ROADMAP.md.
*
* All functions are pure — no I/O, no side effects.
*/
// ─── Types ──────────────────────────────────────────────────────────────────
export interface TruncationOptions {
/** Max content length in characters before truncation kicks in. Default: 8192 */
maxContentLength: number;
}
export const DEFAULT_TRUNCATION_OPTIONS: TruncationOptions = {
maxContentLength: 8192,
};
// ─── Markdown-aware truncation ──────────────────────────────────────────────
/**
* Truncate markdown content while preserving structure.
*
* Strategy: keep YAML frontmatter, all headings, and the first paragraph under
* each heading. Collapse everything else with a line count summary.
*
* Returns the original content unchanged if below maxContentLength.
*/
export function truncateMarkdown(
content: string,
filename: string,
options: TruncationOptions = DEFAULT_TRUNCATION_OPTIONS,
): string {
if (content.length <= options.maxContentLength) return content;
const lines = content.split('\n');
const kept: string[] = [];
let inFrontmatter = false;
let frontmatterDone = false;
let currentSectionLines = 0;
let paragraphKept = false;
let omittedLines = 0;
let inParagraph = false;
for (let i = 0; i < lines.length; i++) {
const line = lines[i];
// Handle YAML frontmatter (preserve entirely)
if (i === 0 && line.trim() === '---') {
inFrontmatter = true;
kept.push(line);
continue;
}
if (inFrontmatter) {
kept.push(line);
if (line.trim() === '---') {
inFrontmatter = false;
frontmatterDone = true;
}
continue;
}
// Heading — always keep, reset paragraph tracking
if (/^#{1,6}\s/.test(line)) {
if (omittedLines > 0) {
kept.push(`[... ${omittedLines} lines omitted]`);
omittedLines = 0;
}
kept.push(line);
currentSectionLines = 0;
paragraphKept = false;
inParagraph = false;
continue;
}
// Empty line — paragraph boundary
if (line.trim() === '') {
if (inParagraph && !paragraphKept) {
// End of first paragraph — mark it kept
paragraphKept = true;
}
if (!paragraphKept || currentSectionLines === 0) {
kept.push(line);
} else {
omittedLines++;
}
inParagraph = false;
continue;
}
// Content line
currentSectionLines++;
if (!paragraphKept) {
// Still in the first paragraph — keep it
kept.push(line);
inParagraph = true;
} else {
omittedLines++;
}
}
if (omittedLines > 0) {
kept.push(`[... ${omittedLines} lines omitted]`);
}
const totalOmitted = lines.length - kept.length;
if (totalOmitted > 0) {
kept.push('');
kept.push(`[Truncated: read .planning/${filename} for full content]`);
}
return kept.join('\n');
}
// ─── Milestone extraction ───────────────────────────────────────────────────
/**
* Extract the current milestone section from a ROADMAP.md.
*
* Parses STATE.md to find the current milestone name, then extracts only
* that milestone's section from the roadmap. Falls back to full content
* if the milestone can't be identified or found.
*/
export function extractCurrentMilestone(
roadmapContent: string,
stateContent?: string,
): string {
if (!stateContent) return roadmapContent;
// Find current milestone from STATE.md
// Patterns: "Current Milestone: X", "milestone: X", "## Current Position" block
const milestonePatterns = [
/current\s*milestone\s*:\s*(.+)/i,
/^milestone\s*:\s*(.+)/im,
/##\s*current\s*position[\s\S]*?milestone\s*:\s*(.+)/i,
];
let milestoneName: string | undefined;
for (const pattern of milestonePatterns) {
const match = stateContent.match(pattern);
if (match) {
milestoneName = match[1].trim();
break;
}
}
if (!milestoneName) return roadmapContent;
// Find the milestone section in roadmap
// Look for heading containing the milestone name
const lines = roadmapContent.split('\n');
let sectionStart = -1;
let sectionEnd = lines.length;
let sectionHeadingLevel = 0;
for (let i = 0; i < lines.length; i++) {
const headingMatch = lines[i].match(/^(#{1,6})\s+(.+)/);
if (!headingMatch) continue;
const level = headingMatch[1].length;
const title = headingMatch[2];
if (sectionStart === -1) {
// Looking for the milestone heading
if (title.toLowerCase().includes(milestoneName.toLowerCase())) {
sectionStart = i;
sectionHeadingLevel = level;
}
} else {
// Found start — look for next heading at same or higher level
if (level <= sectionHeadingLevel) {
sectionEnd = i;
break;
}
}
}
if (sectionStart === -1) return roadmapContent;
// Extract preamble (everything before first milestone heading at the same level)
const preamble: string[] = [];
for (let i = 0; i < lines.length; i++) {
const headingMatch = lines[i].match(/^(#{1,6})\s/);
if (headingMatch && headingMatch[1].length === sectionHeadingLevel && i !== sectionStart) {
// Hit another milestone-level heading before our section
if (i < sectionStart) {
break; // preamble ends at first milestone heading
}
}
if (i < sectionStart) {
// Keep top-level title and intro
if (i === 0 || lines[i].match(/^#\s/) || !lines[i].match(/^#{1,6}\s/)) {
preamble.push(lines[i]);
}
}
}
const milestoneSection = lines.slice(sectionStart, sectionEnd).join('\n');
const otherMilestones = countOtherMilestones(lines, sectionHeadingLevel, sectionStart);
const result = [
...preamble,
'',
milestoneSection,
];
if (otherMilestones > 0) {
result.push('');
result.push(`[${otherMilestones} other milestone(s) omitted — read .planning/ROADMAP.md for full roadmap]`);
}
return result.join('\n').trim();
}
function countOtherMilestones(
lines: string[],
headingLevel: number,
excludeIndex: number,
): number {
let count = 0;
for (let i = 0; i < lines.length; i++) {
if (i === excludeIndex) continue;
const match = lines[i].match(/^(#{1,6})\s/);
if (match && match[1].length === headingLevel) {
count++;
}
}
return count;
}

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@@ -296,6 +296,8 @@ export { GSDEventStream } from './event-stream.js';
export type { EventStreamContext } from './event-stream.js';
export { ContextEngine, PHASE_FILE_MANIFEST } from './context-engine.js';
export type { FileSpec } from './context-engine.js';
export { truncateMarkdown, extractCurrentMilestone, DEFAULT_TRUNCATION_OPTIONS } from './context-truncation.js';
export type { TruncationOptions } from './context-truncation.js';
export { getToolsForPhase, PHASE_AGENT_MAP, PHASE_DEFAULT_TOOLS } from './tool-scoping.js';
export { PromptFactory, extractBlock, extractSteps, PHASE_WORKFLOW_MAP } from './phase-prompt.js';
export { GSDLogger } from './logger.js';

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@@ -154,6 +154,11 @@ describe('PromptFactory', () => {
expect(prompt).toContain('# State');
expect(prompt).toContain('# Roadmap');
expect(prompt).toContain('## Phase Instructions');
// Cache-friendly ordering (#1614): stable prefix before variable context
const phaseInstrIdx = prompt.indexOf('## Phase Instructions');
const contextIdx = prompt.indexOf('## Context');
expect(phaseInstrIdx).toBeLessThan(contextIdx);
});
it('assembles plan prompt with all context files', async () => {

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@@ -102,8 +102,13 @@ export class PromptFactory {
return sanitizePrompt(buildExecutorPrompt(plan, agentDef));
}
// Prompt assembly order is cache-optimized (#1614):
// Stable prefix (deterministic per phase type) → cached by Anthropic at 0.1x cost
// Variable suffix (.planning/ files) → uncached, changes per project/run
const sections: string[] = [];
// ── STABLE PREFIX (cacheable across runs for the same phase type) ──
// ── Agent role ──
const agentDef = await this.loadAgentDef(phaseType);
if (agentDef) {
@@ -131,18 +136,20 @@ export class PromptFactory {
}
}
// ── Phase-specific instructions (hardcoded per phase type — stable) ──
const phaseInstructions = this.getPhaseInstructions(phaseType);
if (phaseInstructions) {
sections.push(`## Phase Instructions\n\n${phaseInstructions}`);
}
// ── VARIABLE SUFFIX (project-specific, changes per run) ──
// ── Context files ──
const contextSection = this.formatContextFiles(contextFiles);
if (contextSection) {
sections.push(contextSection);
}
// ── Phase-specific instructions ──
const phaseInstructions = this.getPhaseInstructions(phaseType);
if (phaseInstructions) {
sections.push(`## Phase Instructions\n\n${phaseInstructions}`);
}
return sanitizePrompt(sections.join('\n\n'));
}