hsf

name

hsf

description

Write specifications using Hybrid Specification Format (HSF v6), a prose-based format optimized for LLM consumption. Uses natural-language instructions within an XML envelope (<purpose>, <scope>, <config>, <instructions>, <rules>, <errors>, <examples>), JSON configuration blocks, XML <route> decision tables for multi-branch logic, <output-schema> for structured output specification, $variable threading for complex data flows, and consolidated error tables. Features 3-tier scaling (Micro/Standard/Complex) and integrated validation. Use when writing specs for LLM agents. Triggers include "write a spec", "write an LLM spec", "create an HSF specification", "write a specification for an agent".

Hybrid Specification Format (HSF v6)

Generate well-structured hybrid specifications from user requests. Given a domain, complexity indicators, and user intent, produce a specification that uses prose instructions within an XML envelope (<purpose>, <scope>, <config>, <instructions>, <rules>, <errors>, <examples>), JSON configuration in <config> blocks, XML <route> decision tables for multi-branch logic, <output-schema> for structured output specification, $variable threading for complex data flows, and consolidated error tables. Follows the correct tier format and passes structural validation.

Not in scope: executing the generated specs, providing domain expertise for spec content, maintaining the validator script, runtime interpretation of specs

{ "validator_path": "${CLAUDE_PLUGIN_ROOT}/skills/hsf/scripts/validate_sesf.py", "reference_path": "${CLAUDE_PLUGIN_ROOT}/skills/hsf/assets/reference.md", "template_path": "${CLAUDE_PLUGIN_ROOT}/skills/hsf/assets/template.md", "examples_path": "${CLAUDE_PLUGIN_ROOT}/skills/hsf/references/examples.md", "line_budget": { "micro": [20, 80], "standard": [80, 200], "complex": [200, 400] }, "tier_threshold": { "route_min_branches": 3 } }

Inputs

• user_request: string - what the user wants specified - required
• domain: string - subject area for the specification - required
• complexity_indicators: signals that inform tier selection (concern count, shared structures, overlapping rules, stateful behavior) - optional
• target_tier: enum [micro, standard, complex] - explicit tier override - optional

Outputs

• specification: string - the complete HSF v6 specification document
• validation_result: pass/fail/warnings from the validator
• extracted_assets: reference material extracted to assets/ if applicable

Tier Selection

micro standard complex standard

When the user explicitly requests a tier via target_tier, use that tier regardless of complexity indicators. When a spec exceeds its tier's line budget, suggest promotion to the next tier.

Instructions

How to Select a Tier

Use the <route> table above. Default to standard when signals are ambiguous. A micro spec that grows past 80 lines SHOULD become standard. A complex spec with only one concern after refactoring SHOULD demote to micro.

How to Structure the Document

Always required (all tiers):

• <purpose> (1-3 sentences — the opening section of the spec)
• <scope> (IN/OUT as bullet lists, or a single "Not in scope" line for micro)
• <config> (if any static params exist — use <config> with JSON body for 3+ values, or inline in prose for fewer)
• <instructions> (the actual procedure — in prose, with clear ### phase/step headers inside)
• <errors> (as a table: Error | Severity | Action)

Required for Standard and Complex only:

• <inputs> / <outputs> (typed parameter lists)
• <rules> (grouped by concern, as prose with bold headers — for cross-cutting rules that apply across ALL phases only)
• <examples> (edge cases only, with pass/fail)

Optional (include only when they add value):

• <route> tables (only for 3+ branch decision logic)
• <config> blocks (only when 3+ configuration values exist)
• <output-schema> blocks (for specifying structured output format)
• $variable threading (only when data flows between phases are complex enough to need explicit tracking)
• Worked examples with derivation chains (only for specs where chain integrity matters)

Removed entirely — do NOT include:

• Meta section (version goes in YAML frontmatter if needed)
• Notation section (symbols are self-evident or explained inline on first use)
• Types section (inline field descriptions where they're used)
• Functions section (logic goes in Instructions or Rules)
• Precedence section (resolve conflicts in the prose directly)
• Dependencies section (agent discovers these from context)
• Changelog section (use git history; version in frontmatter is sufficient)

Forbidden syntax — do NOT use:

• ## Section top-level headers (use XML tags: <purpose>, <scope>, etc.)
• @config blocks (use <config> with JSON body)
• @route tables (use <route> with XML <case> elements)
• $config.key references (use config.key without the $ prefix)

How to Write Rules

Write rules as prose with ### sub-headers and bold list items inside <rules>. Use RFC 2119 keywords (MUST, SHOULD, MAY) for precision. State each constraint ONCE, in the section where it applies.

Do NOT use:

• **BEHAVIOR** or **RULE** keywords
• WHEN/THEN/ELSE syntax
• Scattered inline ERROR declarations after individual rules

Do use:

• ### headers for rule groups (inside <rules>)
• Bold list items (- **Rule name:**) for individual rules
• Natural sentences that combine condition and action
• Consolidated error table inside <errors> at the end

Example of correct rule writing:

<rules>

### Critical Thinking Rules

Apply throughout ALL phases:

- **Professional skepticism:** When a speaker claims something is easy, possible, or valuable — ask: what evidence supports this? What could go wrong? Document both scenarios.
- **Intellectual honesty:** Challenge claims. Identify logical flaws. Provide counterarguments not considered. Flag overconfidence.

</rules>

How to Write Procedures / Instructions

Write procedures as prose inside <instructions> with ### phase headers. Use numbered lists for ordered steps, bullet lists for parallel concerns. Bold key terms.

Do NOT use:

• **PROCEDURE** or **STEP** keywords
• → $variable output declarations (unless data flow between phases is genuinely complex)
• References to BEHAVIOR blocks (inline the actual rules where they apply)

Do use:

• ### headers for phases: ### Phase 1: Extraction
• Numbered lists for sequences within a phase
• Inline constraints where they apply instead of referencing a separate rules section
• $variable threading only when explicit data flow tracking prevents bugs

Example of correct instruction writing:

<instructions>

### Setup

Run `mkdir -p /tmp/scratchpad/`. Create all 6 tasks upfront using TaskCreate.

### Phase 1: Extraction → `phase1_extraction.md`

Read the entire transcript (no skimming). Produce a scratchpad artifact containing:

- **Labeled extracted ideas:** E1, E2, E3... (explicit and implicit)
- **Frameworks and philosophies** identified
- **Critical analysis** of at least 3 major claims

</instructions>

How to Use <route> and <config>

These are the decision-table and configuration mechanisms of HSF.

<route> decision tables:

• Use ONLY for 3+ branch decision logic
• Fewer branches → use a prose conditional instead
• Must specify mode: mode="first_match_wins" or mode="all_matches"
• SHOULD include a <default> element when a meaningful default exists

<config> blocks:

• Use ONLY when 3+ configuration values exist
• Body MUST be valid JSON
• Keys MUST use snake_case
• Values MUST be literals (strings, numbers, arrays, nested objects)
• Reference with config.key or config.nested.key (no $ prefix)
• <config> is for static values only — use $variable threading for runtime data

How to Use <output-schema>

Use <output-schema> to specify structured output formats inline within <instructions>. This is useful when the spec produces JSON, structured objects, or machine-readable output.

When to use:

• SHOULD include for standard and complex tier specs that produce structured output
• MAY include for micro tier specs when output format clarity adds value
• Place inside <instructions>, in the phase that produces the output

Syntax:

<output-schema format="json">
{
  "field_name": "string",
  "score": "float 0.0-1.0",
  "optional_field": "string | null",
  "items": ["string"]
}
</output-schema>

Type annotations: Use descriptive types like "string", "integer", "float 0.0-1.0", "boolean", "string | null", ["string"] (array of strings), or nested objects.

How to Write Examples

Edge cases only — boundary conditions, error paths, non-obvious behavior. If the happy path is obvious from the rules, do not exemplify it. Use the compact single-line format or multi-line worked examples. Place inside <examples>.

Compact format: example_name: input_description → expected_outcome

Worked examples (for specs where derivation chain integrity matters):

[good_example]:
  Input: [concrete values]
  Expected: [concrete outcome]
  Why: [explain which rule applies and the reasoning]

How to Write Errors

Consolidate ALL errors into a single table inside <errors> at the end of the spec:

<errors>

| Error | Severity | Action |
|-------|----------|--------|
| missing_field | critical | halt and report which field is missing |
| over_budget | warning | review for redundancy, suggest promotion |
| empty_result | info | generate empty report, log the date range |

</errors>

Severity values: critical (halt processing), warning (continue with degradation), info (log only).

Do NOT scatter error declarations inline after individual rules.

Rules

Format Compliance

• XML envelope required: MUST use XML tags (<purpose>, <scope>, <config>, <instructions>, <rules>, <errors>, <examples>) for top-level sections. MUST NOT use ## Section markdown headers for top-level sections. ### sub-headers are used for structure within sections.
• No legacy syntax: MUST NOT use @config, @route, or $config.key anywhere in the spec. Use <config> with JSON, <route> with XML cases, and config.key references instead.
• No formal wrappers: MUST NOT use **BEHAVIOR**, **RULE**, **PROCEDURE**, or **STEP** keywords anywhere in the spec. Use ### headers and bold list items instead.
• No empty sections: If a section would say "none" or be blank, omit it entirely. Do not template the absence of content.
• No duplicate constraints: Each rule MUST be stated once, in the section where it applies. No separate "define" then "reference" pattern.
• No notation legend: Symbols ($, →) are self-evident. Explain inline on first use only if genuinely non-obvious for the target audience.
• Errors as consolidated table: All errors MUST appear in a single <errors> table, not scattered inline after rules.
• RFC 2119 keywords preserved: MUST, SHOULD, MAY MUST be capitalized when used with their operative meanings.

Notation Usage

• <route> only for 3+ branches: Fewer branches → prose conditional. The form is determined by branch count, not author preference.
• <config> only for 3+ values: Fewer values → inline in the text.
• $variable threading only for complex flows: Most specs do not need it. "Phase 2 reads the output of Phase 1" is clear enough in prose.
• No <route> outside instructions: <route> tables belong inline in the <instructions> section or in a dedicated routing section — not in separate rule blocks.

Line Budget

• Micro specs SHOULD stay within 20-80 lines
• Standard specs SHOULD stay within 80-200 lines
• Complex specs SHOULD stay within 200-400 lines

Quality Assurance

• Run the validator when the spec is complete: python3 config.validator_path <spec.md> and fix all failures
• Concrete examples only: Examples MUST use concrete values — never placeholders. Cover edge cases and boundary conditions only.
• No ambiguity: Rules MUST NOT use vague language like "handle appropriately", "use common sense", or "extract relevant fields". Specify each case explicitly.
• Reference extraction: When reference/lookup data exceeds 10 lines, extract to assets/ and add a one-line pointer.
• YAML frontmatter: When the specification is a Claude Code skill, it MUST include YAML frontmatter with name and description fields.

Quality Checklist

Check	Rule
XML envelope used	Top-level sections use XML tags, not ## headers
No legacy syntax	No @config, @route, or $config.key anywhere
No empty sections	If a section would say "none" or be blank, omit it entirely
No duplicate constraints	Each rule stated once, in the section where it applies
No formal wrappers on prose	No **BEHAVIOR**, **RULE**, **PROCEDURE**, **STEP** keywords. Use ### headers and bold list items.
<route> only for 3+ branches	Fewer branches → prose conditional
<config> only for 3+ values	Fewer values → inline in the text
Errors in <errors> table	Not scattered inline after rules
RFC 2119 keywords preserved	MUST, SHOULD, MAY still capitalized for precision
Line budget compliance	Micro ≤80, Standard ≤200, Complex ≤400
Edge-case examples only	No happy-path examples
No notation legend	Symbols explained inline on first use if non-obvious

Errors

Error	Severity	Action
formal_wrapper_used	critical	Remove BEHAVIOR/RULE/PROCEDURE/STEP keywords; rewrite as prose with ### headers
empty_section	critical	Delete the empty section entirely
legacy_syntax_used	critical	Replace @config with <config> JSON, @route with <route> XML, $config.key with config.key
missing_xml_envelope	critical	Wrap top-level sections in XML tags; remove ## headers
duplicate_constraint	warning	Remove the duplicate; keep only the instance in the section where it applies
route_under_threshold	warning	Convert <route> with fewer than 3 branches to a prose conditional
config_under_threshold	warning	Inline <config> values referenced fewer than 3 times
over_budget	warning	Review for redundancy, extract reference material, consolidate rules
vague_rule	critical	Rewrite with specific conditions and actions
missing_error_table	warning	Add consolidated error table inside <errors> at end of spec
validation_failure	critical	Fix structural issues identified by the validator
config_key_mismatch	critical	Add key to <config> or fix the reference