docs: FEATURES.md missing 30+ truncation limits, 22 commands, 56 TOML filters

Problem

A comprehensive audit of docs/FEATURES.md against the codebase reveals major documentation gaps. A user lost data because rtk diff silently truncated output (#827) — this is a symptom of a broader issue: truncation behavior is undocumented across 30+ commands.

Audit results

1. Undocumented truncation limits (30+ commands)

Every .take(N) and truncate() call in the codebase should be documented. Key ones:

Command	Hidden limit	Code location
rtk git diff	500 lines max	git.rs:153
rtk git status	15 staged, 10 untracked	git.rs:635,661
rtk grep	200 total, 25/file, 80 chars/line	grep_cmd.rs:122
rtk cargo test	15 errors, 10 failures	cargo_cmd.rs:298,839
rtk docker ps/images	15 containers	container.rs:65,155
rtk kubectl pods	10 items	container.rs:314
rtk psql	30 rows, 20 records	psql_cmd.rs:12-13
rtk pytest	5 failures	pytest_cmd.rs:192
rtk mypy	5 errors	mypy_cmd.rs:193
rtk rspec	5 failures	rspec_cmd.rs:259
rtk rubocop	20 offenses	rubocop_cmd.rs:253
rtk go test	20 errors	go_cmd.rs:462
rtk lint	10 rules, 10 files	lint_cmd.rs:286,294
rtk ruff check	10 rules, 10 files	ruff_cmd.rs:180,188
rtk golangci-lint	10 linters, 10 files	golangci_cmd.rs:220,228
rtk next build	10 routes	next_cmd.rs:146
rtk log	10 errors, 5 warnings	log_cmd.rs:130,171
rtk env	5 PATH, 20 vars	env_cmd.rs:71,106
rtk pip list	20 packages	pip_cmd.rs:216
rtk deps	10 deps, 5 dev_deps	inferred
rtk prettier	10 files	prettier_cmd.rs:136
rtk rake test	10 failures	rake_cmd.rs:229

2. Commands missing from FEATURES.md (22)

• Go: rtk go test, rtk go build, rtk go vet, rtk golangci-lint
• Python: rtk pytest, rtk mypy, rtk pip, rtk ruff
• Ruby: rtk rspec, rtk rubocop, rtk rake test
• .NET: rtk dotnet
• Other: rtk format, rtk gt, rtk session, rtk hook, rtk hook-audit, rtk rewrite, rtk verify, rtk cargo nextest

3. TOML filter system undocumented

56 TOML filters in src/filters/*.toml are not mentioned at all. The declarative filter system (user-extensible via ~/.config/rtk/filters/ and .rtk/filters/) needs its own section.

4. Configuration limits undocumented

[limits]
grep_max_results = 200
grep_max_per_file = 25
status_max_files = 15
status_max_untracked = 10

5. Inaccurate descriptions

• rtk git log: default -n 10 not mentioned
• rtk git status: overflow "+ X more" pattern not described
• rtk grep: per-file limit not documented
• rtk lint: "top 10 rules" grouping not explained

Action items

• Document all truncation limits per command
• Add 22 missing command sections
• Add TOML filter system section
• Document [limits] config section
• Fix inaccurate descriptions
• Add "what is preserved vs filtered" for each command

Related

• #827 — silent truncation in diff (P0, fix in progress)
• #822 — file size truncated