[caoxiaoyuyuyuyuyu]

Summary

RolloutGraph keeps every turn's request_messages. A chat request re-sends the whole conversation and each request body is JSON-decoded on its own, so turn k holds a fresh copy of every image (and other long text) attached in turns 1..k. For multimodal rollouts graph memory therefore grows quadratically with the number of turns: n turns with one base64 image each retain n(n+1)/2 image copies instead of n.

This PR makes add_turn replace long strings (>= 1024 chars) in request_messages, request_tools and response_message with a single graph-local copy.

Type of Change

• Bug fix
• New feature
• Breaking change
• Documentation
• New environment
• Refactoring

Reproduction (synthetic)

Build a graph of 12 turns where turn k re-sends k+1 user messages, each with a distinct 64 KiB data:image/png;base64,... URL, and every request body is passed through json.loads(json.dumps(...)) as the capture server does. Before this change the graph retains 78 distinct image string objects (~5 MiB); after it, 12 (~0.8 MiB).

Why the output is unchanged

• Only immutable str objects are shared; equal strings are swapped for an equal string, so every value is identical.
• Dicts and lists are rebuilt per turn, so message structure is unchanged and mutating one turn's messages cannot affect another turn.
• The table is per RolloutGraph (not process-global), so it is released together with the graph.

RFC Status

• Not required (bug fix, docs, minor refactoring)
• RFC exists: #___
• RFC needed (will create before merge)

Test Plan

New tests/envs/test_capture_graph_shared_text.py (fully synthetic data):

• each image is retained once across all turns (object identity), and all turns reference the first copy;
• editing a nested message field in one turn does not change any other turn;
• export_session(..., include_messages=True) serialised with json.dumps is byte-identical to the export from the same graph with sharing disabled.

Two of the three tests fail on main and all pass with this change.

PYTHONPATH=src:envs uv run pytest tests/envs/test_capture_graph_shared_text.py -q   # 3 passed
PYTHONPATH=src:envs uv run pytest tests/envs -q -k capture --ignore=tests/envs/test_coding_codeact_env.py   # 191 passed, 26 skipped
uv run usort check <changed files> && uv run ruff format --check <changed files> && uv run ruff check src/ tests/   # clean

(test_coding_codeact_env.py fails to collect locally for an unrelated missing optional dependency.)

Claude Code Review

N/A

🤖 Generated with Claude Code

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Note

Low Risk
Memory-only deduplication of immutable strings at graph ingest; behavior and exports are covered by tests, with no auth or training-token logic changes.

Overview
RolloutGraph now interns strings ≥1024 characters when ingesting turns, so repeated base64 image URLs and other long text from re-sent chat history are stored once per graph instead of once per turn.

On add_turn, request_messages, request_tools, and response_message are passed through a recursive _share_text helper that replaces matching long strings with a single graph-local copy while rebuilding lists and dicts per turn (only immutable strings are shared).

Adds tests/envs/test_capture_graph_shared_text.py: multimodal multi-turn graphs retain one object per distinct image, edits in one turn do not leak to others, and export_session JSON is byte-identical with sharing disabled.

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