Harness spec 3.2.0: reasoning goes back during its turn; no absolute paths

context.md §8: every assistant message of the current turn (after the
last message that started a turn — a step-boundary delivery does not)
carries its reasoning back, as reasoning_content in OpenAI chat and as
thinking blocks in Anthropic; earlier turns carry none, which the common
templates render identically. §11: an agent session's prompt names no
absolute machine path: the environment block names the project and says
paths are relative to its root (loop.json context.env), files outside
the project under home as ~/…; relative paths resolve against the
project root, absolute ones still accepted. agents-missing.md and
init.md no longer name the root. New conformance areas: reasoning, paths.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

harness/prompts/blocks/agents-missing.md

@@ -2,7 +2,7 @@
      kept by the agent, and how git is used there is the user's answer, asked once and written down. -->
 ## AGENTS.md
 This project has no AGENTS.md yet. It is the file every later session here starts from, so making it is part of the work:
-- Make it at the first natural pause in real work, once you know what the project is — not before you have done anything, and not in plan mode. It goes at the project root: {{root}}/AGENTS.md.
+- Make it at the first natural pause in real work, once you know what the project is — not before you have done anything, and not in plan mode. It goes at the project root: `AGENTS.md`.
 - Before you write it, ask the user how git is to be used here, with ask_user, in one call: {{git_question}} Mark the options you would recommend.
 - Write their answer under a "## Git" heading. Above it, say briefly what the project is, how to build, run and test it, and the conventions that matter.
 - If the user does not want the file, do not bring it up again this session.