docs(changelog): note routing, translation, and observability changes since #549's coverage in Unreleased

[LeonSGP43]

Follow-up to my earlier #549 (same intent, next window): Unreleased had fallen behind main again — #549 only noted commits up to its merge (2026-08-26, through #533), and the CHANGELOG's last touch was #671 (2026-09-10) while another ~35 commits merged through 9b6efb9 (#641).

Scope

21 new entries covering every user-facing commit in that gap, each grounded in its PR description and diff:

• Added (12) — per-target system_prompt (feat(server): configure system prompts by target #464), auto algorithm type (feat(routing): add auto algorithm type #654), Codex freeform tools + Responses-lite request shape (feat(translation): support Codex freeform tools and the Responses-lite request shape #648), custom tool semantics for the stage router (feat(stage-router): support custom tool semantics #606), restricted LLM router for Rust hosts (feat(server): expose restricted LLM router #586), RoutingOutcome.selected_model_ids (feat: RoutingOutcome has a Vec of selected_model_ids #592), routing outcome metadata (feat(libsy): add routing outcome metadata #647), bounded outcome evidence (feat(libsy): populate bounded outcome evidence #655), outcome metadata in OpenTelemetry and Python (feat(libsy): expose outcome metadata in OpenTelemetry and Python #658), route attribution in the durable log (feat(server): record route attribution in durable log #618), Algorithms select a Category (feat(libsy): Algorithms select a Category (e.g. "efficient") not a specific model. #630), request origin in routing logs (feat(server): record request origin in routing logs #641)
• Fixed (9) — Responses reasoning replayed as input history (fix(translation): replay responses reasoning as input history #645), buffered Responses input hardened for Codex upstreams (fix(translation): harden buffered Responses input for Codex upstreams #664), upstream URLs dropped from transport errors (fix(llm-client): drop upstream urls from transport errors #649), upstream bodies redacted from the client-call span (fix(llm-client): redact upstream body from client-call span #611), reasoning dropped from task classifier history (fix(libsy): drop reasoning from task classifier history #610), escalation judge anchored to task framing (fix(libsy): anchor every pre-reply user message for the escalation judge and log verdicts #639), OpenAI tool strictness preserved for Anthropic (fix(translation): preserve OpenAI tool strictness for Anthropic #600), Anthropic tool strictness preserved (fix(translation): preserve Anthropic tool strictness #585), flat Responses input_file payloads decoded (fix(translation): decode flat Responses input_file payloads #590)

Deliberately skipped

Non-notable per Keep a Changelog practice: CI-only (#677, #676, #679, #673, #674, #678), docs (#659, #613, #625, #628, #629), build (#652, #589), and internal refactors without behavioral change (#591, #605). A few remaining merges (#672, #616, #593, #604/#612, #609) need word-level verification against existing entries before they can be judged in or out, so I left them out rather than guess — happy to do a second pass if you'd like the coverage complete in one PR.

Summary by CodeRabbit

• New Features

  • Added per-target system prompts and automatic routing strategies.
  • Added support for Codex and Responses workflows.
  • Expanded custom tool behavior and routing controls.
  • Added richer routing results, metadata, request-origin details, and durable-log attribution.
  • Added category-based algorithm selection.

• Bug Fixes

  • Improved reasoning replay, request handling, file decoding, and escalation messaging.
  • Preserved tool strictness and improved filtering of classifier history.
  • Redacted sensitive information from transport errors and tracing details.

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• CHANGELOG.md

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Walkthrough

The unreleased changelog documents new routing and integration capabilities. It also records fixes for reasoning replay, request buffering, redaction, classifier history, escalation handling, tool strictness, and Responses file decoding.

Changes

Changelog updates

Layer / File(s)	Summary
New routing and integration features CHANGELOG.md	The changelog adds entries for target-specific prompts, routing strategies, Codex and Responses support, tool classification, routing metadata, telemetry, attribution, category selection, and request-origin logging.
Routing and request-processing fixes CHANGELOG.md	The changelog records fixes for reasoning replay, Codex-compatible buffering, redaction, classifier history, escalation framing, tool strictness, and flat Responses input_file decoding.

Priority: ⬇️ Low

Estimated code review effort: 1 (Trivial) | ~5 minutes

Merge Risk: ⚪ Minimal · up to 5582a

The change updates unreleased documentation only and presents no identified merge-blocking risk.

🚥 Pre-merge checks | ✅ 5

✅ Passed checks (5 passed)

Check name	Status	Explanation
Docstring Coverage	✅ Passed	No functions found in the changed files to evaluate docstring coverage. Skipping docstring coverage check. Docstring coverage is scoped to functions touched by this diff. Analyzed 0 functions across 0…
Linked Issues check	✅ Passed	Check skipped because no linked issues were found for this pull request.
Out of Scope Changes check	✅ Passed	Check skipped because no linked issues were found for this pull request.
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.
Title check	✅ Passed	The title clearly identifies the changelog update and summarizes its main topics: routing, translation, and observability changes added to Unreleased after PR #549.

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_{A rabbit reads the changelog bright
New routes hop into the light
Tools and prompts align
Fixes follow in a line
Every entry ends just right}

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