# chat-verifier-agent Specification

## Purpose
TBD - created by archiving change chat-verifier-agent. Update Purpose after archive.
## Requirements
### Requirement: Verifier SHALL fact-check Executor answers
The system SHALL have a Verifier Agent that reads the Executor's answer and the tool call history, then produces a structured verdict.

#### Scenario: PASS verdict when all claims have evidence
- **WHEN** all critical facts in the Executor's answer have direct or indirect support in tool call results
- **AND** at least one critical fact has direct evidence
- **AND** no critical fact is contradicted
- **THEN** the Verifier SHALL output verdict="PASS" with groundedness_score ≥ 0.5

#### Scenario: LOW_CONFID verdict with partial evidence
- **WHEN** no critical fact contradicts the tool results
- **AND** some critical facts have no supporting evidence
- **THEN** the Verifier SHALL output verdict="LOW_CONFID"

#### Scenario: LOW_CONFID verdict with only indirect support
- **WHEN** no critical fact contradicts the tool results
- **AND** all critical facts are only indirectly supported
- **THEN** the Verifier SHALL output verdict="LOW_CONFID"

#### Scenario: REJECT verdict when claims contradict evidence
- **WHEN** any critical fact in the Executor's answer contradicts tool call results
- **OR** the answer fabricates a key entity, error code, or conclusion that does not exist in the tool evidence
- **THEN** the Verifier SHALL output verdict="REJECT"

### Requirement: Verifier SHALL output structured JSON
The Verifier SHALL output a JSON object with verdict, groundedness_score, facts_checked array, and rationale.

#### Scenario: Output format validation
- **WHEN** the Verifier completes its analysis
- **THEN** the output SHALL contain "verdict", "groundedness_score", "facts_checked", and "rationale" fields
- **AND** groundedness_score SHALL be a float between 0.0 and 1.0
- **AND** verdict SHALL be one of "PASS", "LOW_CONFID", or "REJECT"

#### Scenario: strict schema output
- **WHEN** the Verifier returns its result
- **THEN** it SHALL output exactly one JSON object
- **AND** it SHALL NOT output Markdown, code fences, or explanatory text outside the JSON object
- **AND** the JSON object SHALL include `critical_fact_count`
- **AND** each `facts_checked` item SHALL include `fact`, `is_critical`, `verification`, and `detail`

### Requirement: facts_checked SHALL use a fixed classification set
Each checked fact SHALL be labeled using a fixed evidence classification.

#### Scenario: fact classification values
- **WHEN** the Verifier emits `facts_checked`
- **THEN** each fact SHALL use one of `direct_evidence`, `indirect_support`, `no_evidence`, or `contradicted`

### Requirement: groundedness_score SHALL be derived from fact classifications
The groundedness score SHALL be computed from critical fact classifications instead of being freely chosen by the model.

#### Scenario: contradicted fact forces reject
- **WHEN** any critical fact is labeled `contradicted`
- **THEN** the Verifier SHALL output verdict="REJECT"
- **AND** groundedness_score SHALL be `0.0`

#### Scenario: score derived from supported facts
- **WHEN** no critical fact is contradicted
- **THEN** groundedness_score SHALL be computed from the mapped values of critical facts
- **AND** the implementation SHALL use the fixed mapping `direct_evidence=1.0`, `indirect_support=0.6`, `no_evidence=0.0`
- **AND** the result SHALL be clamped into `[0.0, 1.0]`

### Requirement: ChatService SHALL route based on Verifier verdict
The system SHALL use ChatService for explicit single-round `Planner → Executor → Verifier` orchestration and SHALL use ChatService to control whether an additional round is allowed.

#### Scenario: PASS → direct output
- **WHEN** Verifier outputs verdict="PASS"
- **THEN** the system SHALL output the Executor's answer directly

#### Scenario: LOW_CONFID score≥0.5 → output with disclaimer
- **WHEN** Verifier outputs verdict="LOW_CONFID" with groundedness_score ≥ 0.5
- **THEN** the system SHALL output the Executor's answer prefixed with a fixed confidence disclaimer

#### Scenario: LOW_CONFID score<0.5 → trigger one additional round
- **WHEN** Verifier outputs verdict="LOW_CONFID" with groundedness_score < 0.5 and this is the first callback
- **THEN** the ChatService SHALL invoke one additional `Planner → Executor → Verifier` round to supplement evidence
- **AND** after the second Verifier run, verdict="LOW_CONFID" SHALL be output with a confidence disclaimer
- **AND** after the second Verifier run, verdict="REJECT" SHALL still produce a degraded output

#### Scenario: REJECT does not enter retry round
- **WHEN** Verifier outputs verdict="REJECT"
- **THEN** the system SHALL NOT start a retry round for evidence补充
- **AND** it SHALL produce a degraded output directly

#### Scenario: REJECT → degraded output
- **WHEN** Verifier outputs verdict="REJECT"
- **THEN** the system SHALL output a degraded result indicating the answer cannot be reliably generated
- **AND** it SHALL NOT pass through the raw Executor answer

### Requirement: User-facing verifier outputs SHALL follow fixed templates
The system SHALL use fixed output protocols for LOW_CONFID and REJECT user-facing responses.

#### Scenario: LOW_CONFID uses disclaimer template
- **WHEN** the final verdict is `LOW_CONFID`
- **THEN** the user-facing response SHALL prepend a fixed disclaimer before the Executor answer
- **AND** optional evidence gaps, if present, SHALL come only from verifier-identified critical gaps

#### Scenario: REJECT uses degraded template
- **WHEN** the final verdict is `REJECT`
- **THEN** the user-facing response SHALL use a degraded template
- **AND** it SHALL include only confirmed facts, evidence gaps, and next-step suggestions
- **AND** it SHALL NOT include unverified raw answer content

### Requirement: Verifier SHALL be observable
The Verifier's verdict SHALL be persisted for observability.

#### Scenario: verdict written to self_evaluation
- **WHEN** the Verifier produces a verdict
- **THEN** the ChatService SHALL write the verdict data under `diagnosis_session.self_evaluation.verifier_evaluation`
- **AND** existing `rule_evaluation` data SHALL be preserved

### Requirement: self_evaluation SHALL be a container object
The `diagnosis_session.self_evaluation` field SHALL store multiple evaluation channels in one JSON object.

#### Scenario: rule evaluation stored separately
- **WHEN** the rule-based evidence scoring completes
- **THEN** the EvaluationService SHALL write the result under `rule_evaluation`
- **AND** existing `verifier_evaluation` data SHALL be preserved

#### Scenario: verifier evaluation stored separately
- **WHEN** the Verifier completes
- **THEN** the ChatService SHALL write the result under `verifier_evaluation`
- **AND** existing `rule_evaluation` data SHALL be preserved

#### Scenario: no whole-object overwrite after initialization
- **WHEN** either evaluation channel updates `self_evaluation`
- **THEN** the implementation SHALL use read-modify-write semantics
- **AND** it SHALL NOT replace the whole JSON object except when initializing from null

### Requirement: Verifier SHALL consume explicit verification inputs
The Verifier SHALL receive explicit verification inputs rather than inferring them only from raw conversation history.

#### Scenario: explicit input blocks available to Verifier
- **WHEN** the Verifier starts
- **THEN** the system SHALL provide `original_query`, `executor_final_answer`, and `tool_trace_summary` as explicit inputs
- **AND** `retry_context` SHALL be provided on the second round only
- **AND** message filtering MAY be used only to remove intermediate reasoning or unrelated noise

#### Scenario: tool trace summary derived from tool facts
- **WHEN** the system prepares verifier inputs
- **THEN** `tool_trace_summary` SHALL be generated from tool invocation facts
- **AND** each summary item SHALL include tool name, success state, input summary, output summary, and evidence level
- **AND** raw conversation history SHALL NOT be the only source of verifier evidence context

#### Scenario: tool trace summary preserves invocation references
- **WHEN** the system prepares verifier inputs
- **THEN** each summary item SHALL include a stable `trace_ref`
- **AND** each summary item SHALL preserve `source_invocation_ids` for the tool invocation rows that contributed to the summary
- **AND** each summary item SHOULD include query samples, retrieval layers, relevance levels, and source document labels when available

#### Scenario: only evidence-bearing tools included
- **WHEN** the system generates `tool_trace_summary`
- **THEN** it SHALL include only evidence-bearing tool invocations
- **AND** non-evidence helper tools such as time or formatting tools SHALL be excluded by default

#### Scenario: failed evidence calls preserved as evidence gaps
- **WHEN** an evidence-bearing tool invocation fails or returns no usable evidence
- **THEN** the summary SHALL still include that invocation
- **AND** it SHALL mark the entry as unsuccessful with an evidence level representing no evidence

#### Scenario: repeated tool calls may be compacted
- **WHEN** repeated tool invocations concern the same tool, topic domain, and round
- **THEN** the system MAY compact them into a merged summary entry
- **AND** the merged entry SHALL preserve the first effective hit and the count of repeated, failed, or no-hit calls

#### Scenario: raw outputs not passed through in full
- **WHEN** a tool invocation returns large raw content
- **THEN** `tool_trace_summary` SHALL keep only a minimal evidence summary
- **AND** the raw output SHALL NOT be passed through in full to the Verifier

#### Scenario: MessagesModelHook used only for noise reduction
- **WHEN** a MessagesModelHook is used for the Verifier
- **THEN** it MAY remove intermediate reasoning or irrelevant messages
- **AND** it SHALL NOT be the primary source for assembling verifier business inputs

### Requirement: Verifier facts SHALL be auditable
Verifier facts SHALL be linkable to the evidence summaries used during verification.

#### Scenario: facts_checked contains evidence refs
- **WHEN** the Verifier emits `facts_checked`
- **THEN** each fact SHALL include `evidence_refs`
- **AND** each evidence ref SHALL point to an existing `tool_trace_summary.trace_ref`
- **AND** each evidence ref SHALL preserve the relevant `source_invocation_ids` when available

#### Scenario: verifier evaluation persists traceability snapshot
- **WHEN** the ChatService persists `verifier_evaluation`
- **THEN** it SHALL include `traceability_version`
- **AND** it SHALL include the `tool_trace_summary` snapshot used by the Verifier

### Requirement: Verifier inputs SHALL tolerate hardened no-evidence semantics
The verifier integration SHALL continue to work when evidence summaries distinguish failed calls, no-hit calls, and deduped retrievals more explicitly.

#### Scenario: Failed evidence remains a verifier-visible gap
- **WHEN** an evidence-bearing tool invocation fails
- **THEN** the verifier-facing trace summary SHALL preserve that failure as a gap
- **AND** the verifier flow SHALL continue without crashing

#### Scenario: Deduped retrievals do not count as fresh support
- **WHEN** the verifier-facing trace summary contains deduped `lookup_knowledge` entries
- **THEN** those entries SHALL be treated as no-new-evidence
- **AND** they SHALL NOT be interpreted as fresh direct support for the answer