fix(git): make the blob recovery hint work under RTK's own hook

[KuSh]

Fixes one regression from the release review on #3979, introduced by #3265.

Part of a set of six, one per originating PR: #3681, #3552, #3265 (this), #3772, #3857, #3941.

The regression

A windowed git show <rev>:<path> prints a head and points at the rest of the file:

... (+1434 lines) [see remaining: git show 'HEAD:src/core/utils.rs' | tail -n +249]

Under RTK's own hook, the bare git show in that hint is rewritten back into rtk git show, which windows the dump a second time — so tail -n +249 had nothing left to print but the hint itself.

$ rtk git show HEAD:src/core/utils.rs | tail -1
... (+1434 lines) [see remaining: git show 'HEAD:src/core/utils.rs' | tail -n +249]

$ git show 'HEAD:src/core/utils.rs' | tail -n +249     # following it verbatim, hook active
1 line                                                 # 1434 expected

The fix

Name the command the hook leaves alone. rtk proxy is the documented escape hatch and the diff size hints in src/cmds/git/diff_cmd.rs already use it the same way:

... (+1434 lines) [see remaining: rtk proxy git show 'HEAD:src/core/utils.rs' | tail -n +249]

248 shown lines + 1434 recovered = 1682 = the native git show total, byte for byte.

Verification

tests/git_show_blob_differential_test.rs gained windowed_blob_hint_command_returns_the_rest, which runs the command the hint names instead of simulating it — it parses the hint's own argv, executes it, and asserts head + recovered output reconstructs the blob byte for byte. Against the old hint it fails with the hint returned 1 line(s) -- it must return the rest of the blob, not just itself, so it is a real guard for exactly this regression; the previous tests reconstructed the tail with native git and could never have seen it.

A unit test also asserts the emitted hint is left untouched by discover::registry::rewrite_command, which is the function all three hook front-ends funnel through.

docs/usage/FEATURES.md quoted the old hint string literally; it now shows the rtk proxy form and notes that a bare git show under the hook re-windows.

cargo fmt --all, cargo clippy --all-targets and cargo test --all are green, rebased on current develop.

🤖 Generated with Claude Code

[rtk-wshm-sync-bot]

wshm · Automated triage by AI

📊 Automated PR Analysis

🐛 Type	bug-fix
🟢 Risk	low

Summary

Fixes a regression where the blob recovery hint printed for windowed git show <rev>:<path> output used a bare git show command that RTK's own hook rewrites and re-windows, leaving nothing for tail to print. The hint now points to rtk proxy git show, which the hook leaves untouched, matching the pattern already used by the diff size hints.

Review Checklist

• Tests present
• Breaking change
• Docs updated

Linked issues: #3265, #3979

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Analyzed automatically by wshm · This is an automated analysis, not a human review.

[pszymkowiak]

Reviewed by building the branch and following the hint the way an agent would, with the hook simulated through rtk rewrite.

Verified

• develop: the hint names bare git show 'HEAD:src/core/utils.rs' | tail -n +250; rtk rewrite turns it into rtk git show … | tail -n +250 (exit 3); following it yields 1 line (the hint itself); head + rest ≠ native (sha256 mismatch, 8189+84 bytes vs 65645).
• this PR: hint names rtk proxy git show '…' | tail -n +250; rtk rewrite leaves it alone (exit 1, rtk -prefixed segment returned unchanged at registry.rs:1691, tail -n +N cannot match TAIL_N_SPACE); following it yields 1593 lines; head + rest == native byte for byte (8189 + 57456 = 65645, same sha256).
• Adjacent shapes: path with a space, <sha>:<path>, rtk git -C <abs> show … from outside the repo (hint carries '-C' '<path>' through proxy), small blob → no hint. All correct.
• compact_blob_show has a single production caller (git_cmd.rs:606); no stale copy of the old hint string remains in src/, tests/ or docs/.

One precision note, no code change needed: windowed_blob_hint_command_returns_the_rest executes the hint's rtk proxy git show argv and applies the tail in-process, but does not run the hook; the hook-survival guarantee is the unit test test_compact_blob_show_hint_survives_rtks_own_hook calling the real rewrite_command. Together they cover both halves; the doc comment on the integration test could say so.

Approving. CI green on all three OSes.