refactor(prompt): consolidate template context model

[mariusvniekerk]

Summary

• consolidate the template-facing prompt data model under a single TemplateContext root
• route prompt rendering, fitting, and range fallback selection through the unified context model
• collapse remaining narrow prompt wrapper/view types into thin compatibility shims over the consolidated context

Stack

• base PR: refactor(prompt): make prompt construction template-driven #625 (gotmpl -> main)
• this PR targets gotmpl

Test Plan

• go test ./...

[roborev-ci]

roborev: Combined Review (e6357ab)

Summary verdict: 1 medium-severity issue found; no high or critical findings.

Medium

• internal/prompt/template_context.go:251, internal/prompt/templates/prompt_sections.md.gotmpl:71
  The new fallback model can silently render an empty diff section. diff_block now takes the fallback path whenever .Fallback.HasContent is true, but FallbackContext.Rendered() only renders Text and Dirty.Body. If callers populate Commit, Range, or Generic, the template suppresses .Diff.Body and emits no fallback content.

  Fix: either implement rendering for all structured fallback variants in Rendered()/templates, or make HasContent only report truly renderable content until those branches are supported. Add tests covering commit/range/generic fallback rendering.

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Synthesized from 3 reviews (agents: codex, gemini | types: default, security)

[roborev-ci]

roborev: Combined Review (1281801)

Verdict: 2 medium-severity regressions in prompt behavior should be addressed before merge.

Medium

• internal/prompt/prompt.go:821-839, internal/prompt/templates/prompt_sections.md.gotmpl:29-43
  Range-review prompts no longer include prior per-commit review context for commits inside the reviewed range. The removed InRangeReviews population/rendering path means range reviews can resurface issues that were already found earlier in the stack or fixed by later commits.

• internal/prompt/prompt.go:1126-1139, internal/prompt/templates/prompt_sections.md.gotmpl:135-140
BuildAddressPrompt now merges automated fix attempts and human developer comments into one PreviousAttempts block. That removes the distinct user-comment context and can cause developer guidance to be treated like another failed attempt instead of instructions to honor while fixing.

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Synthesized from 3 reviews (agents: codex, gemini | types: default, security)

[roborev-ci]

roborev: Combined Review (1281801)

Summary: 2 medium-severity issues found; no high or critical findings.

Medium

• Range reviews lost in-range prior review context

  • Location: internal/prompt/prompt.go:821-839, internal/prompt/templates/prompt_sections.md.gotmpl:29-43
  • Finding: Range-review prompts no longer include prior per-commit review context for commits inside the selected range. With the old InRangeReviews population/rendering path removed, the reviewer loses the “already reviewed in this range” guidance and can resurface issues that were already identified or fixed later in the stack.
  • Suggested fix: Restore an equivalent InRangeReviews field in the consolidated context and render it from optional_sections for range prompts.

• Developer comments are conflated with failed fix attempts

  • Location: internal/prompt/prompt.go:1126-1139, internal/prompt/templates/prompt_sections.md.gotmpl:135-140
  • Finding: BuildAddressPrompt now merges automated fix attempts and human developer comments into a single PreviousAttempts block. That removes the dedicated ## User Comments section and reframes operator guidance as just another failed attempt, which can cause the agent to underweight or misinterpret explicit developer instructions.
  • Suggested fix: Keep separate fields for tool attempts and user comments in the address-template context, or preserve the prior split behavior when building the prompt.

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Synthesized from 3 reviews (agents: codex, gemini | types: default, security)