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feat: add cache_control breakpoints to compiler for Anthropic prompt caching #37

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feat: add cache_control breakpoints to compiler for Anthropic prompt caching#37

Description

@pitimon
pitimon
opened on May 4, 2026

Problem

OpenKB compiler reuses a "base context A" (system + document) across N+M+2 LLM calls per document (summary → concepts-plan → N create + M update concept pages). Without cache_control markers, every call re-bills the full document content as input tokens.

For Anthropic Sonnet 4.5 (via OpenRouter or direct), prompt caching can reduce input cost by ~90% on cached prefix and reduce TTFT. Minimum cacheable size is 1,024 tokens, easily exceeded by typical document content.

Proposal

Add cache_control: {"type": "ephemeral"} markers at two breakpoints in openkb/agent/compiler.py:

  1. End of doc_msg in compile_short_doc + compile_long_doc — caches system + doc for all downstream calls (summary, plan, every concept).
  2. End of assistant summary message in _compile_concepts (3 call sites: plan, create, update) — caches system + doc + summary for all concept generation calls.

Two breakpoints, well within Anthropic's max-4 limit.

Compatibility

  • Anthropic / OpenRouter→Anthropic: cache_control honored.
  • OpenAI: list-of-blocks content format is valid (Vision API uses it); cache_control silently ignored.
  • Other providers: LiteLLM normalizes/strips unknown fields.

Side fix

_llm_call_async currently does not forward **kwargs while _llm_call does (asymmetry noted in memory #82886). Add **kwargs for parity.

Out of scope

  • OpenRouter Response Caching (X-OpenRouter-Cache: true) — different mechanism, evaluated separately.
  • Refactoring messages into a dedicated builder module — keep patch surgical.

Test plan

  • Existing pytest suite passes (mocks accept *args, **kwargs).
  • New assertion: completion payload contains cache_control block on the doc_msg.
  • Manual smoke against a real Anthropic key: observe cached_tokens in prompt_tokens_details on calls 2..N.

References

  • Memory observation S11144 (3-5 line patch feasibility, OpenKB compiler audit).
  • CLAUDE.md compiler architecture: "Designed around prompt-cache reuse: a single base context A reused across summary → concept-plan → concept-page calls."

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feat: add cache_control breakpoints to compiler for Anthropic prompt caching · Issue #37 · VectifyAI/OpenKB · GitHub
      Skip to content
      feat: add cache_control breakpoints to compiler for Anthropic prompt caching #37
      Closed
      Closed
      feat: add cache_control breakpoints to compiler for Anthropic prompt caching#37
      Description
      @pitimon
      pitimon
      opened on May 4, 2026
      Problem
      OpenKB compiler reuses a "base context A" (system + document) across N+M+2 LLM calls per document (summary → concepts-plan → N create + M update concept pages). Without cache_control markers, every call re-bills the full document content as input tokens.
      For Anthropic Sonnet 4.5 (via OpenRouter or direct), prompt caching can reduce input cost by ~90% on cached prefix and reduce TTFT. Minimum cacheable size is 1,024 tokens, easily exceeded by typical document content.
      Proposal
      Add cache_control: {"type": "ephemeral"} markers at two breakpoints in openkb/agent/compiler.py:
      1. End of doc_msg in compile_short_doc + compile_long_doc — caches system + doc for all downstream calls (summary, plan, every concept).
      2. End of assistant summary message in _compile_concepts (3 call sites: plan, create, update) — caches system + doc + summary for all concept generation calls.
      Two breakpoints, well within Anthropic's max-4 limit.
      Compatibility
      • Anthropic / OpenRouter→Anthropic: cache_control honored.
      • OpenAI: list-of-blocks content format is valid (Vision API uses it); cache_control silently ignored.
      • Other providers: LiteLLM normalizes/strips unknown fields.
      Side fix
      _llm_call_async currently does not forward **kwargs while _llm_call does (asymmetry noted in memory #82886). Add **kwargs for parity.
      Out of scope
      • OpenRouter Response Caching (X-OpenRouter-Cache: true) — different mechanism, evaluated separately.
      • Refactoring messages into a dedicated builder module — keep patch surgical.
      Test plan
      • Existing pytest suite passes (mocks accept *args, **kwargs).
      • New assertion: completion payload contains cache_control block on the doc_msg.
      • Manual smoke against a real Anthropic key: observe cached_tokens in prompt_tokens_details on calls 2..N.
      References
      • Memory observation S11144 (3-5 line patch feasibility, OpenKB compiler audit).
      • CLAUDE.md compiler architecture: "Designed around prompt-cache reuse: a single base context A reused across summary → concept-plan → concept-page calls."
      Metadata
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feat: add cache_control breakpoints to compiler for Anthropic prompt caching · Issue #37 · VectifyAI/OpenKB · GitHub
          Skip to content
          feat: add cache_control breakpoints to compiler for Anthropic prompt caching #37
          Closed
          Closed
          feat: add cache_control breakpoints to compiler for Anthropic prompt caching#37
          Description
          @pitimon
          pitimon
          opened on May 4, 2026
          Problem
          OpenKB compiler reuses a "base context A" (system + document) across N+M+2 LLM calls per document (summary → concepts-plan → N create + M update concept pages). Without cache_control markers, every call re-bills the full document content as input tokens.
          For Anthropic Sonnet 4.5 (via OpenRouter or direct), prompt caching can reduce input cost by ~90% on cached prefix and reduce TTFT. Minimum cacheable size is 1,024 tokens, easily exceeded by typical document content.
          Proposal
          Add cache_control: {"type": "ephemeral"} markers at two breakpoints in openkb/agent/compiler.py:
          1. End of doc_msg in compile_short_doc + compile_long_doc — caches system + doc for all downstream calls (summary, plan, every concept).
          2. End of assistant summary message in _compile_concepts (3 call sites: plan, create, update) — caches system + doc + summary for all concept generation calls.
          Two breakpoints, well within Anthropic's max-4 limit.
          Compatibility
          • Anthropic / OpenRouter→Anthropic: cache_control honored.
          • OpenAI: list-of-blocks content format is valid (Vision API uses it); cache_control silently ignored.
          • Other providers: LiteLLM normalizes/strips unknown fields.
          Side fix
          _llm_call_async currently does not forward **kwargs while _llm_call does (asymmetry noted in memory #82886). Add **kwargs for parity.
          Out of scope
          • OpenRouter Response Caching (X-OpenRouter-Cache: true) — different mechanism, evaluated separately.
          • Refactoring messages into a dedicated builder module — keep patch surgical.
          Test plan
          • Existing pytest suite passes (mocks accept *args, **kwargs).
          • New assertion: completion payload contains cache_control block on the doc_msg.
          • Manual smoke against a real Anthropic key: observe cached_tokens in prompt_tokens_details on calls 2..N.
          References
          • Memory observation S11144 (3-5 line patch feasibility, OpenKB compiler audit).
          • CLAUDE.md compiler architecture: "Designed around prompt-cache reuse: a single base context A reused across summary → concept-plan → concept-page calls."
          Metadata
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              No branches or pull requests
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try {
var __m = "*";
var __re = new RegExp('^' + ".*" + '
feat: add cache_control breakpoints to compiler for Anthropic prompt caching · Issue #37 · VectifyAI/OpenKB · GitHub
              Skip to content
              feat: add cache_control breakpoints to compiler for Anthropic prompt caching #37
              Closed
              Closed
              feat: add cache_control breakpoints to compiler for Anthropic prompt caching#37
              Description
              @pitimon
              pitimon
              opened on May 4, 2026
              Problem
              OpenKB compiler reuses a "base context A" (system + document) across N+M+2 LLM calls per document (summary → concepts-plan → N create + M update concept pages). Without cache_control markers, every call re-bills the full document content as input tokens.
              For Anthropic Sonnet 4.5 (via OpenRouter or direct), prompt caching can reduce input cost by ~90% on cached prefix and reduce TTFT. Minimum cacheable size is 1,024 tokens, easily exceeded by typical document content.
              Proposal
              Add cache_control: {"type": "ephemeral"} markers at two breakpoints in openkb/agent/compiler.py:
              1. End of doc_msg in compile_short_doc + compile_long_doc — caches system + doc for all downstream calls (summary, plan, every concept).
              2. End of assistant summary message in _compile_concepts (3 call sites: plan, create, update) — caches system + doc + summary for all concept generation calls.
              Two breakpoints, well within Anthropic's max-4 limit.
              Compatibility
              • Anthropic / OpenRouter→Anthropic: cache_control honored.
              • OpenAI: list-of-blocks content format is valid (Vision API uses it); cache_control silently ignored.
              • Other providers: LiteLLM normalizes/strips unknown fields.
              Side fix
              _llm_call_async currently does not forward **kwargs while _llm_call does (asymmetry noted in memory #82886). Add **kwargs for parity.
              Out of scope
              • OpenRouter Response Caching (X-OpenRouter-Cache: true) — different mechanism, evaluated separately.
              • Refactoring messages into a dedicated builder module — keep patch surgical.
              Test plan
              • Existing pytest suite passes (mocks accept *args, **kwargs).
              • New assertion: completion payload contains cache_control block on the doc_msg.
              • Manual smoke against a real Anthropic key: observe cached_tokens in prompt_tokens_details on calls 2..N.
              References
              • Memory observation S11144 (3-5 line patch feasibility, OpenKB compiler audit).
              • CLAUDE.md compiler architecture: "Designed around prompt-cache reuse: a single base context A reused across summary → concept-plan → concept-page calls."
              Metadata
              Metadata
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                No labels
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                No type
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                No projects
                  Milestone
                  No milestone
                  Relationships
                  None yet
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                  No branches or pull requests
                  Issue actions
                  
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feat: add cache_control breakpoints to compiler for Anthropic prompt caching · Issue #37 · VectifyAI/OpenKB · GitHub
                  Skip to content
                  feat: add cache_control breakpoints to compiler for Anthropic prompt caching #37
                  Closed
                  Closed
                  feat: add cache_control breakpoints to compiler for Anthropic prompt caching#37
                  Description
                  @pitimon
                  pitimon
                  opened on May 4, 2026
                  Problem
                  OpenKB compiler reuses a "base context A" (system + document) across N+M+2 LLM calls per document (summary → concepts-plan → N create + M update concept pages). Without cache_control markers, every call re-bills the full document content as input tokens.
                  For Anthropic Sonnet 4.5 (via OpenRouter or direct), prompt caching can reduce input cost by ~90% on cached prefix and reduce TTFT. Minimum cacheable size is 1,024 tokens, easily exceeded by typical document content.
                  Proposal
                  Add cache_control: {"type": "ephemeral"} markers at two breakpoints in openkb/agent/compiler.py:
                  1. End of doc_msg in compile_short_doc + compile_long_doc — caches system + doc for all downstream calls (summary, plan, every concept).
                  2. End of assistant summary message in _compile_concepts (3 call sites: plan, create, update) — caches system + doc + summary for all concept generation calls.
                  Two breakpoints, well within Anthropic's max-4 limit.
                  Compatibility
                  • Anthropic / OpenRouter→Anthropic: cache_control honored.
                  • OpenAI: list-of-blocks content format is valid (Vision API uses it); cache_control silently ignored.
                  • Other providers: LiteLLM normalizes/strips unknown fields.
                  Side fix
                  _llm_call_async currently does not forward **kwargs while _llm_call does (asymmetry noted in memory #82886). Add **kwargs for parity.
                  Out of scope
                  • OpenRouter Response Caching (X-OpenRouter-Cache: true) — different mechanism, evaluated separately.
                  • Refactoring messages into a dedicated builder module — keep patch surgical.
                  Test plan
                  • Existing pytest suite passes (mocks accept *args, **kwargs).
                  • New assertion: completion payload contains cache_control block on the doc_msg.
                  • Manual smoke against a real Anthropic key: observe cached_tokens in prompt_tokens_details on calls 2..N.
                  References
                  • Memory observation S11144 (3-5 line patch feasibility, OpenKB compiler audit).
                  • CLAUDE.md compiler architecture: "Designed around prompt-cache reuse: a single base context A reused across summary → concept-plan → concept-page calls."
                  Metadata
                  Metadata
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                    No labels
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                      None yet
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                      No branches or pull requests
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try {
var __m = "*";
var __re = new RegExp('^' + ".*" + '
feat: add cache_control breakpoints to compiler for Anthropic prompt caching · Issue #37 · VectifyAI/OpenKB · GitHub
                      Skip to content
                      feat: add cache_control breakpoints to compiler for Anthropic prompt caching #37
                      Closed
                      Closed
                      feat: add cache_control breakpoints to compiler for Anthropic prompt caching#37
                      Description
                      @pitimon
                      pitimon
                      opened on May 4, 2026
                      Problem
                      OpenKB compiler reuses a "base context A" (system + document) across N+M+2 LLM calls per document (summary → concepts-plan → N create + M update concept pages). Without cache_control markers, every call re-bills the full document content as input tokens.
                      For Anthropic Sonnet 4.5 (via OpenRouter or direct), prompt caching can reduce input cost by ~90% on cached prefix and reduce TTFT. Minimum cacheable size is 1,024 tokens, easily exceeded by typical document content.
                      Proposal
                      Add cache_control: {"type": "ephemeral"} markers at two breakpoints in openkb/agent/compiler.py:
                      1. End of doc_msg in compile_short_doc + compile_long_doc — caches system + doc for all downstream calls (summary, plan, every concept).
                      2. End of assistant summary message in _compile_concepts (3 call sites: plan, create, update) — caches system + doc + summary for all concept generation calls.
                      Two breakpoints, well within Anthropic's max-4 limit.
                      Compatibility
                      • Anthropic / OpenRouter→Anthropic: cache_control honored.
                      • OpenAI: list-of-blocks content format is valid (Vision API uses it); cache_control silently ignored.
                      • Other providers: LiteLLM normalizes/strips unknown fields.
                      Side fix
                      _llm_call_async currently does not forward **kwargs while _llm_call does (asymmetry noted in memory #82886). Add **kwargs for parity.
                      Out of scope
                      • OpenRouter Response Caching (X-OpenRouter-Cache: true) — different mechanism, evaluated separately.
                      • Refactoring messages into a dedicated builder module — keep patch surgical.
                      Test plan
                      • Existing pytest suite passes (mocks accept *args, **kwargs).
                      • New assertion: completion payload contains cache_control block on the doc_msg.
                      • Manual smoke against a real Anthropic key: observe cached_tokens in prompt_tokens_details on calls 2..N.
                      References
                      • Memory observation S11144 (3-5 line patch feasibility, OpenKB compiler audit).
                      • CLAUDE.md compiler architecture: "Designed around prompt-cache reuse: a single base context A reused across summary → concept-plan → concept-page calls."
                      Metadata
                      Metadata
                      Assignees
                      No one assigned
                        Labels
                        No labels
                        No labels
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                        No type
                        Projects
                        No projects
                          Milestone
                          No milestone
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                          No branches or pull requests
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try {
var __m = "*";
var __re = new RegExp('^' + ".*" + '
feat: add cache_control breakpoints to compiler for Anthropic prompt caching · Issue #37 · VectifyAI/OpenKB · GitHub
                          Skip to content
                          feat: add cache_control breakpoints to compiler for Anthropic prompt caching #37
                          Closed
                          Closed
                          feat: add cache_control breakpoints to compiler for Anthropic prompt caching#37
                          Description
                          @pitimon
                          pitimon
                          opened on May 4, 2026
                          Problem
                          OpenKB compiler reuses a "base context A" (system + document) across N+M+2 LLM calls per document (summary → concepts-plan → N create + M update concept pages). Without cache_control markers, every call re-bills the full document content as input tokens.
                          For Anthropic Sonnet 4.5 (via OpenRouter or direct), prompt caching can reduce input cost by ~90% on cached prefix and reduce TTFT. Minimum cacheable size is 1,024 tokens, easily exceeded by typical document content.
                          Proposal
                          Add cache_control: {"type": "ephemeral"} markers at two breakpoints in openkb/agent/compiler.py:
                          1. End of doc_msg in compile_short_doc + compile_long_doc — caches system + doc for all downstream calls (summary, plan, every concept).
                          2. End of assistant summary message in _compile_concepts (3 call sites: plan, create, update) — caches system + doc + summary for all concept generation calls.
                          Two breakpoints, well within Anthropic's max-4 limit.
                          Compatibility
                          • Anthropic / OpenRouter→Anthropic: cache_control honored.
                          • OpenAI: list-of-blocks content format is valid (Vision API uses it); cache_control silently ignored.
                          • Other providers: LiteLLM normalizes/strips unknown fields.
                          Side fix
                          _llm_call_async currently does not forward **kwargs while _llm_call does (asymmetry noted in memory #82886). Add **kwargs for parity.
                          Out of scope
                          • OpenRouter Response Caching (X-OpenRouter-Cache: true) — different mechanism, evaluated separately.
                          • Refactoring messages into a dedicated builder module — keep patch surgical.
                          Test plan
                          • Existing pytest suite passes (mocks accept *args, **kwargs).
                          • New assertion: completion payload contains cache_control block on the doc_msg.
                          • Manual smoke against a real Anthropic key: observe cached_tokens in prompt_tokens_details on calls 2..N.
                          References
                          • Memory observation S11144 (3-5 line patch feasibility, OpenKB compiler audit).
                          • CLAUDE.md compiler architecture: "Designed around prompt-cache reuse: a single base context A reused across summary → concept-plan → concept-page calls."
                          Metadata
                          Metadata
                          Assignees
                          No one assigned
                            Labels
                            No labels
                            No labels
                            Type
                            No type
                            Projects
                            No projects
                              Milestone
                              No milestone
                              Relationships
                              None yet
                              Development
                              No branches or pull requests
                              Issue actions
                              
, 'i');
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style = document.createElement('style');
style.id = 'universal-dark-mode-style';
document.head.appendChild(style);
}
// Dark mode CSS - inverts colors but preserves images/video
style.textContent = '
/* Invert everything except media */
html {
filter: invert(1) hue-rotate(180deg) !important;
background: #1a1a2e !important;
}
/* Restore images, videos, iframes, canvas */
img, video, iframe, canvas, svg, picture, [style*="background-image"] {
filter: invert(1) hue-rotate(180deg) !important;
}
/* Preserve specific elements that should not be inverted */
.no-dark-mode, .no-dark-mode *,
[data-theme="light"], [data-theme="light"],
.ace_editor, .ace_editor *,
.CodeMirror, .CodeMirror *,
.monaco-editor, .monaco-editor *,
.markdown-body pre, .markdown-body pre *,
.highlight, .highlight *,
pre code, pre code * {
filter: none !important;
}
/* Fix common UI elements */
.modal, .popup, .dropdown-menu, .tooltip, .popover {
filter: invert(1) hue-rotate(180deg) !important;
background: #2d2d44 !important;
border-color: #444 !important;
}
/* Scrollbars */
::-webkit-scrollbar { background: #1a1a2e !important; }
::-webkit-scrollbar-thumb { background: #444 !important; }
::-webkit-scrollbar-thumb:hover { background: #555 !important; }
/* Selection */
::selection { background: #4ecdc4 !important; color: #1a1a2e !important; }
::-moz-selection { background: #4ecdc4 !important; color: #1a1a2e !important; }
';
}
function removeDarkMode() {
var style = document.getElementById('universal-dark-mode-style');
if (style) style.remove();
}
// Toggle with Alt+Shift+D
document.addEventListener('keydown', function(e) {
if (e.altKey && e.shiftKey && e.key === 'D') {
e.preventDefault();
enabled = !enabled;
if (enabled) {
applyDarkMode();
console.log('[Universal Dark Mode] Enabled');
} else {
removeDarkMode();
console.log('[Universal Dark Mode] Disabled');
}
}
});
// Apply on load
applyDarkMode();
// Re-apply on dynamic content
var observer = new MutationObserver(function(mutations) {
if (enabled && !document.getElementById('universal-dark-mode-style')) {
applyDarkMode();
}
});
observer.observe(document.head, { childList: true });
console.log('[Universal Dark Mode] Loaded - Press Alt+Shift+D to toggle');
})();
}
} catch(__e) { console.warn('[Userscript:Universal Dark Mode]', __e); }
})();
})();
feat: add cache_control breakpoints to compiler for Anthropic prompt caching · Issue #37 · VectifyAI/OpenKB · GitHub
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                              feat: add cache_control breakpoints to compiler for Anthropic prompt caching #37
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                              feat: add cache_control breakpoints to compiler for Anthropic prompt caching#37
                              Description
                              @pitimon
                              pitimon
                              opened on May 4, 2026
                              Problem
                              OpenKB compiler reuses a "base context A" (system + document) across N+M+2 LLM calls per document (summary → concepts-plan → N create + M update concept pages). Without cache_control markers, every call re-bills the full document content as input tokens.
                              For Anthropic Sonnet 4.5 (via OpenRouter or direct), prompt caching can reduce input cost by ~90% on cached prefix and reduce TTFT. Minimum cacheable size is 1,024 tokens, easily exceeded by typical document content.
                              Proposal
                              Add cache_control: {"type": "ephemeral"} markers at two breakpoints in openkb/agent/compiler.py:
                              1. End of doc_msg in compile_short_doc + compile_long_doc — caches system + doc for all downstream calls (summary, plan, every concept).
                              2. End of assistant summary message in _compile_concepts (3 call sites: plan, create, update) — caches system + doc + summary for all concept generation calls.
                              Two breakpoints, well within Anthropic's max-4 limit.
                              Compatibility
                              • Anthropic / OpenRouter→Anthropic: cache_control honored.
                              • OpenAI: list-of-blocks content format is valid (Vision API uses it); cache_control silently ignored.
                              • Other providers: LiteLLM normalizes/strips unknown fields.
                              Side fix
                              _llm_call_async currently does not forward **kwargs while _llm_call does (asymmetry noted in memory #82886). Add **kwargs for parity.
                              Out of scope
                              • OpenRouter Response Caching (X-OpenRouter-Cache: true) — different mechanism, evaluated separately.
                              • Refactoring messages into a dedicated builder module — keep patch surgical.
                              Test plan
                              • Existing pytest suite passes (mocks accept *args, **kwargs).
                              • New assertion: completion payload contains cache_control block on the doc_msg.
                              • Manual smoke against a real Anthropic key: observe cached_tokens in prompt_tokens_details on calls 2..N.
                              References
                              • Memory observation S11144 (3-5 line patch feasibility, OpenKB compiler audit).
                              • CLAUDE.md compiler architecture: "Designed around prompt-cache reuse: a single base context A reused across summary → concept-plan → concept-page calls."
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