feat: smart budget fraction for extended context windows#5
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sadlilas wants to merge 1 commit intomicrosoft:mainfrom
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feat: smart budget fraction for extended context windows#5sadlilas wants to merge 1 commit intomicrosoft:mainfrom
sadlilas wants to merge 1 commit intomicrosoft:mainfrom
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When context_window > 200k (e.g. Anthropic 1M beta), use fraction-based budgeting instead of standard formula. Default 0.15 keeps sessions in standard pricing zone while using extended window as safety net. Closes microsoft-amplifier/amplifier-support#57 🤖 Generated with [Amplifier](https://github.com/microsoft/amplifier) Co-Authored-By: Amplifier <240397093+microsoft-amplifier@users.noreply.github.com>
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Read context_budget_cap from provider defaults and cap the computed budget. Providers with pricing cliffs (Anthropic, Gemini) set this to keep sessions in the standard pricing zone while preserving the full context window as a safety net. Providers without pricing cliffs (OpenAI) don't set the key and are unaffected. Applied in both the get_model_info() and get_info().defaults code paths. Replaces the fraction-based approach (PR microsoft#5) which applied uniformly to all providers regardless of their pricing model. Related: microsoft-amplifier/amplifier-support#57 🤖 Generated with [Amplifier](https://github.com/microsoft/amplifier) Co-Authored-By: Amplifier <240397093+microsoft-amplifier@users.noreply.github.com>
sadlilas
added a commit
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that referenced
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Feb 22, 2026
Read context_budget_cap from provider defaults and cap the computed budget. Providers with pricing cliffs (Anthropic, Gemini) set this to keep sessions in the standard pricing zone while preserving the full context window as a safety net. Providers without pricing cliffs (OpenAI) don't set the key and are unaffected. Applied in both the get_model_info() and get_info().defaults code paths. Replaces the fraction-based approach (PR microsoft#5) which applied uniformly to all providers regardless of their pricing model. Related: microsoft-amplifier/amplifier-support#57 🤖 Generated with [Amplifier](https://github.com/microsoft/amplifier) Co-Authored-By: Amplifier <240397093+microsoft-amplifier@users.noreply.github.com>
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Summary
When
context_window > 200k(e.g. Anthropic 1M beta), use fraction-based budgeting instead of the standardcontext_window - reserved_output - safety_marginformula.Default
extended_context_budget_fraction = 0.15keeps sessions in the standard pricing zone (~149k budget for 1M context) while using the extended window as a safety net against overflow errors.What Changed
Single file:
amplifier_module_context_simple/__init__.py(+45 lines)EXTENDED_CONTEXT_THRESHOLD = 200_000andDEFAULT_EXTENDED_BUDGET_FRACTION = 0.15extended_context_budget_fraction(float, default 0.15)_calculate_budget()with an extended-context branch in both theget_model_info()and legacyget_info().defaultscode pathsBudget Math
200k - (16k * 0.5) - 1k1M * 0.15 - 1k1M * 0.20 - 1kcontext-persistent Coverage
context-persistentinherits fromSimpleContextManagerand delegatesget_messages_for_request()tosuper(). The_calculate_budget()method lives entirely in context-simple. This fix covers both modules with no changes needed in context-persistent.Test Results
test_tool_result_truncation_phase1) confirmed failing on main before this changeRelated
Closes microsoft-amplifier/amplifier-support#57