30 KiB
Auto-Parser Architecture
The auto-parser automatically analyzes chat templates to determine how to parse model outputs, including content, reasoning, and tool calls.
Overview
The unified auto-parser uses a pure differential, compositional approach (inspired by the git diff algorithm) to analyze chat templates:
Core Philosophy:
- Minimize Hardcoded Patterns: All markers extracted through template comparison (the only heuristic is JSON detection to distinguish
JSON_NATIVEfrom tag-based formats) - Compositional Architecture: Separate analyzer structs for reasoning, content, and tools — each responsible for its own analysis and parser construction
Analysis + Parser Building in Two Steps:
autoparser::autoparser tmpl_analysis(tmpl)— runs all differential comparisons and populates the analysis structsautoparser::peg_generator::generate_parser(tmpl, params, tmpl_analysis)— uses the analysis to build a PEG parser and optional GBNF grammar
Data Structures
All structs are defined in common/chat-auto-parser.h.
Top-Level: autoparser (main analyzer and generator)
common/chat-auto-parser.h:367-388 — top-level analysis result aggregating jinja_caps, reasoning, content, and tools sub-analyses, plus preserved_tokens (union of all non-empty markers).
analyze_reasoning
common/chat-auto-parser.h:254-274 — reasoning analysis result: mode enum, start marker (e.g. <think>), and end marker (e.g. </think>).
analyze_content
common/chat-auto-parser.h:280-295 — content analysis result: mode enum, start/end markers, and requires_nonnull_content flag.
analyze_tools and its sub-structs
- common/chat-auto-parser.h:176-194 —
tool_format_analysis:modeenum,section_start/end,per_call_start/end, JSON field names (function_field,name_field,args_field,id_field,gen_id_field), and format flags (fun_name_is_key,tools_array_wrapped,uses_python_dicts) - common/chat-auto-parser.h:196-200 —
tool_function_analysis:name_prefix,name_suffix,closemarkers around function names - common/chat-auto-parser.h:202-210 —
tool_arguments_analysis:start/endcontainer markers,name_prefix/suffix,value_prefix/suffix,separator - common/chat-auto-parser.h:212-217 —
tool_id_analysis:posenum,prefix/suffixmarkers around call ID values - common/chat-auto-parser.h:301-361 —
analyze_tools: aggregates the four sub-structs above
Enums
reasoning_mode: How the template handles reasoning/thinking blocks.
| Value | Description |
|---|---|
NONE |
No reasoning markers detected |
TAG_BASED |
Tag-based: <think>...</think> (start can be empty for delimiter-style formats) |
TOOLS_ONLY |
Reasoning only appears in tool call responses, not plain content |
Reasoning Prefill: Extracted in generate_parser() by inspecting the rendered prompt suffix. Three cases:
- Start+end at prompt end (e.g.
<think></think>): prefill = canonicalstart + endmarkers (preserving the analyzer's whitespace, e.g. trailing\n). The parser sees reasoning as opened and immediately closed. - Just start at prompt end (e.g.
<think>\n): prefill = extracted from the prompt to preserve trailing whitespace. The parser sees reasoning as already opened. - Start marker in prompt suffix but not at end (e.g. Apriel's
<|begin_assistant|>followed by template boilerplate): the start marker is a template artifact falsely detected by the diff analyzer. It is cleared from the parser so reasoning uses delimiter-style (empty start). The distinction from case 2 vs a genuinely model-generated start marker (e.g.<think>for Granite) is whether the marker appears in the prompt suffix at all.
The prefill is prepended to model output before PEG parsing, fed to the grammar sampler via llama_sampler_accept, and used to determine the reasoning budget sampler's initial state (COUNTING if prefill starts with the reasoning start tokens, IDLE otherwise).
content_mode: How the template wraps assistant content.
| Value | Description |
|---|---|
PLAIN |
No content markers |
ALWAYS_WRAPPED |
Content always wrapped: <response>...</response> |
WRAPPED_WITH_REASONING |
Content wrapped only when reasoning is present |
tool_format: Classification of tool call structure.
| Value | Description |
|---|---|
NONE |
No tool support detected |
JSON_NATIVE |
Pure JSON: {"name": "X", "arguments": {...}} |
TAG_WITH_JSON |
Tag-based with JSON args: <function=X>{...}</function> |
TAG_WITH_TAGGED |
Tag-based with tagged args: <param=key>value</param> |
call_id_position: Where call IDs appear in tag-based formats.
| Value | Description |
|---|---|
NONE |
No call ID support detected |
PRE_FUNC_NAME |
Before function name |
BETWEEN_FUNC_AND_ARGS |
Between function name and arguments |
POST_ARGS |
After arguments |
Tool Calling Formats
JSON_NATIVE
Structure: The entire tool call (function name, arguments, values) is in JSON format. Optional enclosing tags around the section.
Detection: Function name appears inside a JSON structure (quotes preceded by { or :).
Examples:
Standard OpenAI-style:
<tool_call>
{"name": "get_weather", "arguments": {"location": "Paris", "unit": "celsius"}}
</tool_call>
Mistral Nemo with array wrapper:
[TOOL_CALLS]
[{"name": "calculate", "arguments": {"expr": "2+2"}}]
Function name as JSON key (Apertus style):
{"get_weather": {"location": "Paris"}}
TAG_WITH_JSON
Structure: Function name is outside JSON, in tag attributes or XML-style tags. Arguments are a JSON object.
Detection: Function name not in JSON, but argument names appear in JSON context.
Examples:
Functionary v3.1:
<function=get_weather>{"location": "Paris", "unit": "celsius"}</function>
MiniMax:
<minimax:tool_call>
<tool_name>calculate</tool_name>
<arguments>{"expr": "2+2"}</arguments>
</minimax:tool_call>
TAG_WITH_TAGGED
Structure: Both function name and argument names are in XML-style tags. String values are unquoted; non-string values are JSON-formatted.
Detection: Neither function name nor argument names appear in a JSON context.
Examples:
Qwen/Hermes XML format:
<function=get_weather>
<param=location>Paris</param>
<param=unit>celsius</param>
</function>
Mixed types:
<function=calculate>
<param=expr>2+2</param>
<param=precision>2</param>
<param=options>{"round": true}</param>
</function>
String values (Paris, celsius, 2+2) are unquoted; options (object type) is JSON-formatted.
Analysis Flow
autoparser::autoparser(tmpl)
|
|-- Phase 1: analyze_reasoning(tmpl, jinja_caps.supports_tool_calls)
| |-- R1: compare_reasoning_presence() — with/without reasoning_content field
| |-- R2: compare_thinking_enabled() — enable_thinking=false vs true
| '-- R3: compare_reasoning_scope() — reasoning+content vs reasoning+tools
| (only if supports_tool_calls)
|
|-- Phase 2: analyze_content(tmpl, reasoning)
| '-- C1: compares content-only vs tools output and content-only vs reasoning output
|
|-- Phase 3: analyze_tools(tmpl, jinja_caps, reasoning)
| (skipped entirely if !jinja_caps.supports_tool_calls)
| |
| |-- T1: analyze_tool_calls() — no tools vs with tools; classifies format
| | |-- JSON path → analyze_tool_call_format_json_native()
| | '-- tag path → analyze_tool_call_format_non_json()
| |
| (if format != NONE and format != JSON_NATIVE:)
| |
| |-- T2: check_per_call_markers() — 1 call vs 2 calls; moves section→per-call if needed
| | (only if supports_parallel_tool_calls)
| |
| |-- T3: extract_function_markers() — func_alpha vs func_beta; extracts name prefix/suffix/close
| |
| |-- T4: analyze_arguments() — (TAG_WITH_TAGGED only)
| | |-- A1: extract_argument_name_markers() — arg_name_A vs arg_name_B
| | '-- A2: extract_argument_value_markers() — value "XXXX" vs "YYYY"
| |
| |-- T5: extract_argument_separator() — 1 arg vs 2 args; finds separator between args
| |
| |-- T6: extract_args_markers() — 0 args vs 1 arg; finds args container markers
| |
| '-- T7: extract_call_id_markers() — call_id "call00001" vs "call99999"
|
'-- collect_preserved_tokens() — union of all non-empty markers
|
'-- apply workarounds() — post-hoc patches for edge-case templates
|
v
autoparser (analysis result)
|
v
autoparser::peg_generator::generate_parser(tmpl, inputs, analysis)
|-- analysis.build_parser(inputs) — builds PEG parser arena
| |-- reasoning.build_parser(ctx) — reasoning parser (mode-dependent)
| |-- content.build_parser(ctx) — content parser (mode-dependent)
| '-- tools.build_parser(ctx) — tool parser (dispatches by tool_format)
| |-- build_tool_parser_json_native()
| |-- build_tool_parser_tag_json()
| '-- build_tool_parser_tag_tagged()
|
|-- Build GBNF grammar (if tools present and trigger_marker non-empty)
'-- Set grammar_triggers from section_start or per_call_start
|
v
common_chat_params (prompt, parser, grammar, triggers, preserved_tokens)
Entry Point
The auto-parser is invoked in common/chat.cpp:1280-1310 in common_chat_templates_apply_jinja. A few specialized templates are handled first (Ministral/Magistral Large 3, GPT-OSS with <|channel|>, Functionary v3.2 with >>>all), then the auto-parser handles everything else via autoparser::autoparser + peg_generator::generate_parser.
Algorithm Details
Core Mechanism: Differential Comparison
All analysis phases use the same factorized comparison function declared in common/chat-auto-parser-helpers.h:68:
compare_variants(tmpl, params_A, params_modifier)
This creates variant B by applying a modifier lambda to a copy of params_A, renders both through the template, and computes a diff_split (common/chat-auto-parser.h:28-37):
prefix— common prefix between A and Bsuffix— common suffix between A and Bleft— unique to variant Aright— unique to variant B
The diff is computed via calculate_diff_split(), which finds the longest-common-prefix and longest-common-suffix, then iteratively moves incomplete <...> or [...] markers from the prefix/suffix into left/right until stable (tag boundary fixing).
Text is segmentized into markers and non-marker fragments using segmentize_markers(), which splits on <...> and [...] boundaries.
Phase 1: Reasoning Analysis
R1 — compare_reasoning_presence(): Compares assistant message with vs without a reasoning_content field.
- Searches
diff.right(output with reasoning) for the reasoning content needle - Uses PEG parsers to find surrounding markers:
- If both pre/post markers found in
diff.right→TAG_BASED(both tags visible in diff = no forced close) - If both found but post marker only in the full output B →
FORCED_CLOSED - If only post marker found →
TAG_BASED(delimiter-style, empty start)
- If both pre/post markers found in
- Sets
reasoning.startandreasoning.end
R2 — compare_thinking_enabled(): Compares enable_thinking=false vs true with a generation prompt.
- Detects template-added reasoning markers:
enable_thinking=trueadds a non-empty marker at the end of the prompt — setsreasoning.start, mode =TAG_BASED - Detects start+end pattern:
enable_thinking=falseproduces both start+end markers;enable_thinking=trueproduces only start marker — both classified asTAG_BASED - Handles the reverse case: if both start and end are still empty, looks for a single-segment diff on each side to extract both markers
- The reasoning prefill (markers added by the template) is later extracted in
generate_parser()and prepended to model output before parsing
R3 — compare_reasoning_scope(): Compares assistant message with reasoning+text-content vs reasoning+tool-calls.
- Only runs if
jinja_caps.supports_tool_calls - Detects
TOOLS_ONLY: reasoning content present in B (with tools) but not in A (with text content) - Extracts reasoning markers from the tool call output using PEG parsers
Phase 2: Content Analysis
C1: Two comparisons in the analyze_content constructor:
- Comparison 1: content-only output vs tool-call output →
diff_tools - Comparison 2: content-only output vs reasoning+empty-content output →
diff_reasoning
Classification logic:
PLAIN:diff_tools.leftequals the response string (content is the entire diff, no wrapper)ALWAYS_WRAPPED: markers found surrounding the content text inpure_content→ extractsstart/end
Phase 3: Tool Call Analysis
T1 — analyze_tool_calls(): Compares no-tools vs with-tools output.
- Extracts the tool call section as
diff.right - Calls
analyze_tool_call_format()which first strips reasoning markers from the haystack, then:- Calls
in_json_haystack()for both function name and argument name needles in_json_haystack()uses a PEG parser to check whether the needle appears in a JSON context (preceded by{or:with surrounding quotes)- If function name is in JSON →
JSON_NATIVE→analyze_tool_call_format_json_native() - If function name not in JSON, arg name is in JSON →
TAG_WITH_JSON - If neither in JSON →
TAG_WITH_TAGGED analyze_tool_call_format_json_native(): parses the JSON object, matches field values to needles to populatename_field,args_field,id_field,gen_id_field; detectstools_array_wrapped; extractssection_start/section_endanalyze_tool_call_format_non_json(): uses PEG parsers on the haystack to find up to two opening markers (section + per-call) then up to two closing markers
- Calls
T2 — check_per_call_markers(): Compares 1 call vs 2 calls.
- Computes a secondary diff of the second call portion vs the common suffix
- If the second call content starts with
section_start→ the section marker is actually per-call → movessection_start/endtoper_call_start/endand clears the section markers
T3 — extract_function_markers(): Compares function name FUN_FIRST vs FUN_SECOND (two different named functions).
- Finds where the function name appears in
diff.left - Extracts
function.name_prefixfrom the common prefix up to the function marker, andfunction.name_suffixfrom after the name up to the next marker - Extends
name_suffixintodiff.suffix(to the first marker for TAG_WITH_TAGGED; to the first{or[for TAG_WITH_JSON) - Extracts
function.closefrom after the last argument value up to the per-call/section end marker
T4 — analyze_arguments() (TAG_WITH_TAGGED only):
- A1
extract_argument_name_markers(): Comparesarg_name_Avsarg_name_B(two different argument names).- Finds shared surrounding structure →
arguments.name_prefix,arguments.name_suffix
- Finds shared surrounding structure →
- A2
extract_argument_value_markers(): Compares argument value"XXXX"vs"YYYY"(same arg, different value).- Finds markers surrounding the value →
arguments.value_prefix,arguments.value_suffix
- Finds markers surrounding the value →
T5 — extract_argument_separator(): Compares 1 argument vs 2 arguments (same function).
- Uses
until_common_prefix(diff.right, ARG_FIRST, ARG_SECOND)to find what separates the two argument blocks
T6 — extract_args_markers(): Compares 0 arguments vs 1 argument.
- Uses
until_common_prefix()andafter_common_suffix()with the empty and single-arg JSON strings as anchors to find container markers (arguments.start,arguments.end)
T7 — extract_call_id_markers(): Compares call IDs "call00001" vs "call99999".
- Determines whether function name appears in
diff.prefixordiff.suffixto classify position:- Function name in prefix only →
BETWEEN_FUNC_AND_ARGSorPOST_ARGS(further distinguished by where{appears) - Function name in suffix only →
PRE_FUNC_NAME
- Function name in prefix only →
- Extracts
call_id.prefixandcall_id.suffixmarkers around the call ID value - Clears
per_call_endif it incorrectly incorporated the call ID suffix
Workarounds
A workaround array in common/chat-diff-analyzer.cpp applies post-hoc patches after analysis. Each workaround is a lambda that inspects the template source and overrides analysis results. Current workarounds:
- Old Qwen/DeepSeek thinking templates — source contains
content.split('</think>'): setsreasoning.mode = FORCED_OPENwith<think>/</think>markers if no reasoning was detected - Granite 3.3 — source contains specific "Write your thoughts" text: forces
TAG_BASEDreasoning with<think>/</think>andWRAPPED_WITH_REASONINGcontent with<response>/</response> - Cohere Command R+ — source contains
<|CHATBOT_TOKEN|>: setsALWAYS_WRAPPEDcontent mode if no content start is already set - Functionary 3.1 — source contains
set has_code_interpreter: forcesPLAINcontent, specificper_call_start/end, clears preserved tokens to only keep Functionary-specific markers - DeepSeek-R1-Distill-Qwen — source contains
tool▁calls▁beginmarkers: overrides tool section/per-call markers with the correct Unicode block characters
Parser Building
Each analyzer struct (analyze_reasoning, analyze_content, analyze_tools) implements build_parser(parser_build_context&). They share a parser_build_context that carries the PEG builder, inference inputs, the pre-built reasoning parser, and a pointer to the content analyzer.
Reasoning Parser (analyze_reasoning::build_parser)
| Mode | Parser |
|---|---|
| Not extracting reasoning | eps() |
TAG_BASED or TOOLS_ONLY (non-empty start) |
optional(start + reasoning(until(end)) + end) |
TAG_BASED or TOOLS_ONLY (empty start) |
optional(reasoning(until(end)) + end) — delimiter-style |
Note: The start marker may be empty either because the analyzer detected delimiter-style reasoning, or because generate_parser() cleared a template artifact start marker (see Reasoning Prefill above). The reasoning prefill is prepended to model output before parsing.
Content Parser (analyze_content::build_parser)
| Condition | Parser |
|---|---|
json_schema present |
reasoning + space() + content(schema(json(), "response-format", ...)) + end() |
| Tools present | Dispatches to analyze_tools::build_parser() |
ALWAYS_WRAPPED with reasoning |
reasoning + start + content(until(end)) + end + end() |
ALWAYS_WRAPPED without reasoning |
content(until(start)) + start + content(until(end)) + end + end() |
| Default (PLAIN) | reasoning + content(rest()) + end() |
Tool Parsers (analyze_tools::build_parser)
Dispatches by format.mode:
build_tool_parser_json_native(): Calls p.standard_json_tools() which internally dispatches to:
build_json_tools_function_is_key()— function name is the JSON key:{"get_weather": {...}}build_json_tools_nested_keys()— nested:{"function": {"name": "X", "arguments": {...}}}build_json_tools_flat_keys()— flat:{"name": "X", "arguments": {...}}
Handles content wrappers, array wrapping (tools_array_wrapped), parallel calls, and parameter_order.
build_tool_parser_tag_json(): For each tool function:
tool_open(name_prefix + tool_name(literal(name)) + name_suffix) +
call_id_section +
tool_args(schema(json(), tool_schema))
[+ function.close if non-empty]
Wrapped in per-call markers (with optional parallel call repetition) then optionally in section markers.
build_tool_parser_tag_tagged(): For each tool function, builds one parser per argument:
- String types:
tool_arg_string_value(schema(until(value_suffix), ...)) - JSON types:
tool_arg_json_value(schema(json(), ...)) - Required args are plain; optional args wrapped in
optional() - Arguments joined with
space()between consecutive parsers
For closing: uses function.close if present; otherwise uses peek(per_call_end) to avoid premature close during partial streaming; falls back to tool_close(space()) to trigger mapper callbacks.
All three tool parsers return:
reasoning + optional(content(until(trigger_marker))) + tool_calls + end()
Python Dict Format
When format.uses_python_dicts is true (detected when single-quoted strings appear in JSON argument context), build_parser() pre-registers a json-string rule that accepts both single-quoted and double-quoted strings. This is done before any p.json() call so all JSON parsing inherits the flexible rule.
Mapper
common_chat_peg_mapper maps PEG parse results (AST nodes) into common_chat_msg structures. Key design:
- Buffered arguments: Before
tool_nameis known, argument text goes toargs_buffer; once the name is set, the buffer is flushed tocurrent_tool->arguments args_target(): Returns a reference to whichever destination is currently active (buffer or tool args), eliminating branchingclosing_quote_pending: Tracks whether a closing"needs to be appended when a string argument value is finalized (for schema-declared string types in tagged format)- Quote normalization: Python-style quotes (
'key': 'value') are converted to JSON ("key": "value") - Brace auto-closing: At tool close, unclosed
{braces are closed automatically
Files
| File | Purpose |
|---|---|
common/chat-auto-parser.h |
All analysis structs, enums, autoparser, peg_generator, templates_params |
common/chat-auto-parser-generator.cpp |
Parser generator: generate_parser() and build_parser() methods |
common/chat-diff-analyzer.cpp |
Differential analysis implementation and workarounds |
common/chat-auto-parser-helpers.h/cpp |
calculate_diff_split(), segmentize_markers(), |
compare_variants(), string helpers |
|
common/chat-peg-parser.h/cpp |
common_chat_peg_builder, common_chat_peg_mapper, and helpers |
common/chat.cpp |
Entry point: common_chat_templates_apply_jinja() |
tools/parser/debug-template-parser.cpp |
Debug tool for template analysis |
tools/parser/template-analysis.cpp |
Template analysis tool |
Testing & Debugging
Debug Tools
Template Debugger: tools/parser/debug-template-parser.cpp
- Usage:
./bin/llama-debug-template-parser path/to/template.jinja - Shows detected format, markers, generated parser, and GBNF grammar
Template Analysis: tools/parser/template-analysis.cpp
- Usage:
./bin/llama-template-analysis path/to/template.jinja
Debug Logging: Enable with LLAMA_LOG_VERBOSITY=2
- Shows detailed analysis steps, pattern extraction results, and generated parser structure
PEG Test Builder: Fluent API for creating test cases — see tests/test-chat.cpp:947-1043. Example usage:
auto tst = peg_tester("models/templates/Template.jinja");
tst.test("input text")
.reasoning_format(COMMON_REASONING_FORMAT_AUTO)
.tools({tool_json})
.parallel_tool_calls(true)
.enable_thinking(true)
.expect(expected_message)
.run();
Tested Templates
The following templates have active tests in tests/test-chat.cpp:
| Template | Format | Notes |
|---|---|---|
| Ministral-3-14B-Reasoning | Reasoning | [THINK]...[/THINK] tags (specialized handler) |
| NVIDIA-Nemotron-3-Nano-30B | TAG_WITH_TAGGED | Reasoning + tools |
| CohereForAI Command-R7B | JSON_NATIVE | <|START_THINKING|>/<|START_RESPONSE|> markers |
| Google Gemma 2 2B | Content only | No tool support |
| Qwen-QwQ-32B | Reasoning | Forced-open thinking |
| NousResearch Hermes 2 Pro | JSON_NATIVE | <tool_call> wrapper |
| IBM Granite 3.3 | JSON_NATIVE | <think></think> + <response></response> |
| ByteDance Seed-OSS | TAG_WITH_TAGGED | Custom <seed:think> and <seed:tool_call> tags |
| Qwen3-Coder | TAG_WITH_TAGGED | XML-style tool format |
| DeepSeek V3.1 | JSON_NATIVE | Forced thinking mode |
| GLM-4.6 | TAG_WITH_TAGGED | <tool_call>name\n<arg_key>...<arg_value>... format |
| GLM-4.7-Flash | TAG_WITH_TAGGED | Updated GLM format |
| Kimi-K2-Thinking | JSON_NATIVE | Reasoning + JSON tools |
| Apertus-8B-Instruct | JSON_NATIVE | Function name as JSON key |
| MiniMax-M2 | TAG_WITH_JSON | XML invoke with JSON args |
| NVIDIA-Nemotron-Nano-v2 | JSON_NATIVE | <TOOLCALL> wrapper (nested) |
| CohereForAI Command-R Plus | JSON_NATIVE | Markdown code block format |
| Mistral-Nemo-Instruct-2407 | JSON_NATIVE | [TOOL_CALLS] wrapper with ID field |
| Functionary v3.1 | TAG_WITH_JSON | <function=X> format |
| Functionary v3.2 | Specialized | >>> recipient delimiter (dedicated handler) |
| Fireworks Firefunction v2 | TAG_WITH_JSON | Fireworks tool format |
| DeepSeek R1 Distill (Llama/Qwen) | Reasoning | Forced-open thinking |
| llama-cpp-deepseek-r1 | Reasoning | Forced-open thinking |
| Kimi-K2 / Kimi-K2-Instruct | JSON_NATIVE | JSON tools with special markers |
| Llama 3.1/3.2/3.3 | JSON_NATIVE | Standard Llama tool format |
| OpenAI GPT-OSS | Specialized | Channel-based (dedicated handler) |
| Apriel 1.5 | JSON_NATIVE | <tool_calls> wrapper with JSON array |
| Apriel 1.6 Thinker | Reasoning | Implicit reasoning start |
| Mistral Small 3.2 | JSON_NATIVE | [TOOL_CALLS]func[ARGS]{...} with call ID |
| Devstral | JSON_NATIVE | [TOOL_CALLS]func[ARGS]{...} without call ID |
| StepFun 3.5 Flash | TAG_WITH_TAGGED | <function=X><parameter=Y> format |
Adding Support for New Templates
To support a new template format:
- If it follows standard patterns — The auto-parser should detect it automatically. Run
llama-debug-template-parserto verify markers are correctly extracted. - If differential analysis extracts incorrect markers — Add a workaround lambda to the
workaroundsvector incommon/chat-diff-analyzer.cpp. Inspect the template source for a unique identifying substring. - If it needs fundamentally different handling — Add a dedicated handler function in
chat.cppbefore the auto-parser block (as done for GPT-OSS, Functionary v3.2, and Ministral).
Edge Cases and Quirks
- Reasoning Prefill: See the
reasoning_modeenum section above for the full description. Key detail: template artifact detection (case 3) checks the last 500 characters of the rendered prompt for the start marker. If found but not at the very end, the start marker is cleared from the parser. - Per-Call vs Per-Section Markers: Some templates wrap each tool call individually (
per_call_start/end); others wrap the entire section (section_start/end). T2 (check_per_call_markers()) disambiguates by checking if the second call in a two-call output starts with the section marker. - Python Dict Format: The Seed template family uses single-quoted JSON (
'key': 'value'). Theuses_python_dictsflag causes the PEG builder to register a flexiblejson-stringrule accepting both quote styles before any JSON rules are built. - Tag Boundary Fixing:
calculate_diff_split()iteratively adjusts prefix/suffix boundaries to avoid splitting<tag>or[marker]tokens, ensuring clean extraction. - Call ID Side Effects: When a call ID is detected,
per_call_endmay have been incorrectly set to include the call ID suffix. T7 clearsper_call_endin this case. - Tool Analysis Gating:
analyze_toolsis only constructed (and all tool analysis phases run) whenjinja_caps.supports_tool_callsis true. Within tool analysis,check_per_call_markers()(T2) only runs ifjinja_caps.supports_parallel_tool_calls. analyze_arguments()Gating: Within tool analysis, A1 and A2 (argument name/value marker extraction) only run forTAG_WITH_TAGGEDformat.extract_argument_separator()andextract_args_markers()run for all non-JSON_NATIVEformats.