hooks/hermes: add transform_tool_result output filter for high-token tools

[cfournel]

Summary

Adds a Hermes plugin (hooks/hermes/rtk-rewrite/) that registers two hooks:

Hook 1 — pre_tool_call: automatic command rewriting

Rewrites bare terminal commands (find, grep, cat, ls, …) to their rtk equivalents before execution, using rtk rewrite as the single source of truth. Workers benefit automatically without needing to prefix commands manually — identical to the Claude Code PreToolUse hook but applied inside Hermes so all backends (local, Docker, SSH, Modal) benefit.

Worker command	Executed as
find /home -name '*.py'	rtk find /home -name '*.py'
grep -rn foo /src	rtk grep -rn foo /src
cat large_file.yaml	rtk read large_file.yaml
ls -la /some/dir	rtk ls -la /some/dir
python3 script.py	unchanged

Hook 2 — transform_tool_result: output filtering

Filters high-token tool outputs before they enter the conversation context:

Tool(s)	Filter	Limit
terminal	JSON-unwrap, deduplicate, strip blanks	100 lines
browser_navigate	Strip Layout* accessibility noise, deduplicate, truncate	120 lines
read_file, execute_code	Deduplicate, strip blank lines	100 lines
write_file, patch	Replace unified diff with 1-line summary	—
search_files	Truncate results	50 results
kanban_show, kanban_list	Keep last 10 events	10 events

The write_file/patch filter is the main fix for context overflow on patch-heavy tasks — a 50-line diff becomes [patch] src/foo.cs (2 hunks, +5/-3 lines).

All filters fail open — if parsing fails or RTK is absent, the original output is passed through unchanged.

Motivation

Observed in Hermes kanban worker logs over 24h (pigwars board):

Bare command	Count	Notable cost
find	60	2× timeout [exit 124] at 10–15s
ls	19	unfiltered directory trees
grep	13	full match dumps
cat	5	large Unity YAML files

Context overflow crashes (context length exceeded at ~41k tokens) were traced to unfiltered write_file/patch diffs and large browser_navigate snapshots accumulating across turns.

Files changed

• hooks/hermes/rtk-rewrite/__init__.py — plugin implementation (pre_tool_call + transform_tool_result)
• hooks/hermes/rtk-rewrite/plugin.yaml — hook declarations
• hooks/hermes/README.md — full documentation for both hooks
• hooks/hermes/tests/test_transform_tool_result.py — 44 tests covering all filters

Test plan

• 44 unit tests for all transform_tool_result filters (all pass)
• Existing 18 pre_tool_call tests (all pass)
• Worker runs bare find /home -name '*.py' → executes as rtk find, output filtered
• Worker runs python3 script.py → passes through unchanged
• rtk absent from PATH → all commands execute normally, one warning logged
• write_file with 50-line diff → result replaced with 1-line [patch] summary
• browser_navigate with Layout* noise → snapshot stripped and truncated
• kanban_show with 80 events → truncated to last 10

🤖 Generated with Claude Code

[cfournel]

This allows also to compact tools output in Hermes kanban so all cards are optimized too .

[CLAassistant]

All committers have signed the CLA.