[Chen Yufeiyang (feiiiiii5)]

Motivation and Context

The template helper created by create_template_helper_from_function computes the positional arguments passed by Jinja2 or Handlebars, but only merges keyword arguments into KernelArguments. A call such as {{ p_greet('Ada', '?') }} therefore invokes the function with its defaults (Hello, world!) or fails with “parameter is required” even though the template supplied the values. ADR 0023 requires Handlebars kernel-function helpers to support positional arguments.

Description

Positional arguments are mapped to the function's template-facing parameters in declaration order before invocation. Parameters injected by the kernel (kernel, service, execution_settings, arguments) are skipped, and too many positional arguments raise FunctionExecutionException instead of being silently ignored. Keyword arguments still override positional ones.

Tests cover sync Jinja2, sync Handlebars (including the leading context argument), async Jinja2, too many arguments, and a function with a kernel-injected parameter. The five new cases fail on 483ffb4 with the default values/no exception and pass on this branch. tests/unit/prompt_template, tests/unit/contents, tests/unit/template_engine, and tests/unit/text exit 0; ruff check and ruff format --check are clean.

Contribution Checklist

• The code builds clean without errors or warnings in the targeted suites.
• The PR follows the SK contribution guidelines; ruff check/format pass on the two changed files.
• All targeted unit tests pass, and regression tests were added.
• Named and keyword arguments keep their existing precedence; varargs are not specially supported.

[Copilot]

🟡 Changes recommended

The injected-name filter excludes valid prompt-function inputs, causing incorrect argument binding or rejected calls.

1 open issue

• Preserve service input names for prompt-backed functions · New

What changed in this PR

This PR enables positional arguments in Python template helpers so Jinja2 and Handlebars calls pass supplied values to kernel functions.

Changes:

• Maps positional arguments to declared parameters before applying keyword overrides.
• Skips kernel-injected parameters and rejects excess positional arguments.
• Adds regression tests for synchronous and asynchronous helpers, Handlebars context handling, and injected parameters.

File	Description
python/​tests/​unit/​prompt_template/​test_template_helper.py	Adds positional-argument regression coverage.
python/​semantic_kernel/​prompt_template/​utils/​template_function_helpers.py	Maps and validates positional arguments in template helpers.

_{Review effort: Balanced}

[Chen Yufeiyang (feiiiiii5)]

Fixed in 26d8c9e: injected names are filtered only for method-backed functions. Prompt function inputs retain those names. The regression uses a real KernelFunctionFromPrompt with service/kernel/execution_settings/arguments, one and two positional inputs, and sync/async Jinja plus Handlebars. All 24 cases failed before the fix; the complete prompt_template suite now passes 258 tests.