fix(server): retry transient V2 initial title failures

[saphid]

Initial V2 title generation now retries transient provider failures twice with exponential backoff, rechecking that the request is current. Missing-provider and missing-CLI failures use distinct typed errors and do not retry. Exhaustion keeps the existing title and clears the marker; explicit regeneration remains single-attempt. JSON title envelopes are decoded before normalization and truncation.

Current head 988aa940d includes current V2 base 7dd9873ed and the shared test-only prerequisite #10865. Merge #10865 first; the topic itself changes 10 files. This rebuild removes the obsolete merged-base history from the PR diff.

Validation: 113 focused tests pass across the affected feature and foundation persistence coverage. Scoped server typecheck passes (plus contracts for title generation); targeted lint, formatting and diff checks pass. New-head CI is pending.

Independent cross-provider review was unavailable: the direct Claude Opus 5 high launcher in this audit exited 1 with expired OAuth before inference. No Claude review is claimed.

Targets Orchestrator V2 in #2829. Updated with GPT-6 in Codex/T3.

[macroscopeapp]

Approvability

Verdict: Approved at 988aa94

Macroscope's review found this PR approvable — This is a narrowly scoped server fix that adds a bounded retry policy for transient initial title-generation failures and introduces additive typed error distinctions to avoid retrying unavailable providers or CLIs. Supporting tests cover recovery, retry exhaustion, and non-retryable failures, with no product-default or deployment changes.

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[t3-code]

reviewed diff and relevant surrounding code at 1d528851d9e0a5b6e3171da0b8b29bfdd7f678ed. no blocking findings.

retry wraps the request-id check, so each attempt rechecks staleness. retries remain bounded and initial-only; explicit non-retryable errors and interruption retain their separate paths. reviewed the recovery/exhaustion/non-retryable tests and the resolved prior finding. no code changes needed. the effect suite was not rerun locally.

ci snapshot: no failing or pending checks; some checks are skipped. this is a comment review, not an approval or merge.

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[macroscopeapp]

Macroscope has since reviewed this pull request. An earlier review was skipped by a cost limit; a review has now completed, so that notice no longer applies.

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