Allow shared evidence and bounded causal diagnosis with retry feedback

docs/diagnosis-decision-v2.md

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+# Evidence-grounded diagnosis decision v2
+
+The decision is whether an adequately supported cause justifies a bounded,
+verifiable change, not whether every conceivable cause has been excluded.
+There remains at least one targeted alternative countercheck; unlimited
+investigation of theoretical or newly proposed hypotheses is not required.
+
+Evidence IDs are usable across hypotheses, including root-cause support and
+counterchecks. The record's hypothesis ID is provenance only. Technical checks
+still require actual referenced findings; a schema-only capture is insufficient
+for causal support or a meaningful countercheck. The evaluator must explain
+which prerequisite/prediction a finding tests and respect its coverage. Absence
+within a complete filtered snapshot is not absence of all possible runtime paths.
+
+New diagnosis contexts freeze evaluation_protocol=2. diagnosis_v2 and
+diagnosis_early_v2 require decision_basis: causal_explanation, scope_limits,
+sufficient_for_change and contradictions. Each material contradiction cites
+known evidence and records its resolution and reason. A confirmed output cannot
+claim sufficient support while marking a material contradiction unresolved.
+Unfinished alternatives require explicit remaining_uncertainty; another supported
+hypothesis is not automatically a contradiction or an obligation to research it.
+
+The deterministic validator checks structure, identities, references, nonempty
+findings, consistency and declared unresolved contradictions. Semantic relevance,
+whether findings are actually contradictory, adequacy of a countercheck, and
+whether prose overstates evidence remain LLM judgments. The structure does not
+prove that a model has detected every contradiction or told the truth. Prompts
+explicitly reject unjustified universal exclusion and require scoped claims.
+
+Cause confidence and implementation readiness remain separate. Change Request
+and output checks are unchanged; missing implementation data must not be invented.
+This does not add dynamic hypothesis creation or change investigation budgets.
+
+Every new diagnosis retry includes prior failure codes, call references and
+correction guidance from the same review namespace. It never overwrites the
+frozen base context. The precise request is reproducible after a restart and
+when validating accepted output. A pending historical call retains its old
+prompt/hash; after a historical rejection the next fresh attempt uses v2 with
+feedback. Completed historical diagnoses remain replayable.
+
+The current live case is not rewritten or auto-approved by this change. Its
+stored response can be structurally tested offline under shared-evidence rules;
+that is not a new semantic review of its reasoning. No extra summary LLM is used.