[WeiLinCool]

Closes #868

What was wrong

PTC can evaluate a program in a runtime that retains state, so a top-level const/let/class/function outlives the program that declared it. A second declaration of that name is a SyntaxError at compile time and the whole program is discarded before its first line runs, tool calls included. A program that throws keeps its names as well — bindings are instantiated before evaluation — so a failed program cannot be retried verbatim: the retry dies on a name, not on its arguments. The name is never reclaimable: there is no way to delete a lexical binding, and const is not a context property, so Object.keys cannot even enumerate it.

In the session that filed #868 (127 run_code programs) this was 11 of 17 failures (65% of failures, 8.7% of programs). Two were retries of a program that had already failed. Names declared on turn 1 (q1, e1) still collided on turn 6, and failed programs left ~70 permanently unusable names.

The shipped guidance taught the pattern: its Step 3 example is const [load, head] = await Promise.all([...]), and the model copied load into the next program, dying on program two.

The change

release/0.5.5 rewrote the same file. This branch is rebased onto the current master (which contains 0.5.5), so the diff against the 0.5.5 text is 15 lines:

• ## One session, one scope — a top-level name can outlive its program, a second one is a compile-time error that discards the whole program, a failed program keeps its names, so each program owns its names and a retry renames.
• Two mistake-table rows — the same top-level name in a second program; re-sending a failed program with new arguments.
• BATCHING_GUIDANCE_REVISION → '5' (0.5.5 already used 4).

What this deliberately does not do: wrap the examples in { }. That was the first shape of this PR and it is incompatible with 0.5.5: test/batching-examples.test.mjs compiles and executes every shipped example through an AsyncFunction and asserts the returned summary, so an example has to return, and return cannot live inside a bare block. Switching the examples to console.log silently removed them from that test's coverage — I reverted it for that reason.

The stronger alternative, if maintainers prefer 0% over 5%: wrap each example body in return await (async () => { ... })(). It keeps the returned value, keeps batching-examples green, and makes the names local, at the cost of turning every example into an IIFE. Say the word and I will send it as a follow-up.

Validation

A. Model-driven A/B over one audit task in a retained REPL — same model, same task, same run_code contract, only --guidance differs, 4 runs per arm, 14-program budget:

guidance	programs	discarded by a redeclaration	rate
0.5.5 text	56	7	12.5%
this branch	56	3	5.4%

$ node bench/probes/probe-scope-run.mjs --guidance /tmp/rev055.md --steps 14 --json
$ node bench/probes/probe-scope-run.mjs --guidance prompts/batching-guidance.md --steps 14 --json

B. Why the examples are not the vehicle — bench/probes/probe-scope-guidance.mjs runs every fenced example twice in one retained REPL. Both texts score 6 of 7 redeclared, because the examples are unchanged; that is the measurement that says this fix has to be the rule, not the shape.

C. Suite — npm run verify on this branch (darwin-arm64): 247 of 248 suites pass, 7 skipped. The one failure is preset-fragment, which compares the shipped presets/ops-ptc.patch.yml checksum against the locally installed host checkout; that checkout is at a newer commit (838665e0… vs the recorded ce02148b…), and this branch does not touch presets/. It passes in CI, where the host is installed from the pinned range.

D. CI required — green on the rebased head: https://github.com/T-Auto/dsh-ops/actions/runs/43458558329

node-floor              success  2m50s
source-size             success
rust-lint               success
workflow-lint           success
tools-trial             success
validate (linux-x64)    success  3m48s
validate (win32-x64)    success  7m40s
validate (darwin-x64)   success  6m55s
validate (darwin-arm64) success  3m29s
CI required             success

An earlier run of the same content was red twice for infrastructure reasons, not for this change: validate (darwin-arm64) was cancelled with zero steps and no runner assigned, and validate (darwin-x64) failed once on test/native-guidance.test.mjs:59, which waits for the Native reader to be published and then asserts the official read is already hidden — publication and hiding are two steps, so a loaded runner can lose that race. Both legs pass on the current head.