fix(import): raise the pm read buffer past 1 MiB and preview updates in non-atomic --dry-run

[unbraind]

Two defects, both found by running the importer against a real 443-item workspace instead of fixtures

Both fail — or mislead — precisely when a tracker is mature enough for the integration to matter.

1. Import dies on any tracker over 1 MiB, with nothing to diagnose

readPmItems() spawned pm list-all --full --include-body without a maxBuffer, so Node's 1 MiB spawnSync default applied. The real workspace used for testing dumps 1,052,859 bytes — 4 KiB over the cap — so the child was killed and the result came back as:

status: null   error.code: ENOBUFS   stderr: ""

readPmItems() only checks result.status !== 0 and reports result.stderr || "pm list-all failed", so every import, atomic plan and sync against that workspace failed with a bare pm list-all failed and no cause. Nothing in the message hints at a buffer limit, so the natural next step is to go hunting for a broken tracker.

Fixed by capping at 64 MiB — the same cap pm-changelog, pm-context and pm-brief already settled on — applied to readPmItems(), the central pmRun() spawner (a large pm show --json has the same exposure) and the afterCommand hook's pm show. A buffer overrun is now named explicitly and suggests narrowing the import (--labels, --since) instead of surfacing as an unexplained failure.

2. Non-atomic --dry-run previewed every issue as a create

const shouldMatchExisting = !opts.dryRun || opts.atomic;   // ← skipped the index on a plain dry run

With the provenance index never built, match was always undefined, so the preview counted every issue as an import:

[dry-run] Would import 29, skip 0.        ← before
[dry-run] Would import 24, update 5, skip 0.   ← after (matches the real plan)

A preview that overstates creates reads as "this will duplicate my whole tracker", which is the single thing --dry-run exists to rule out. --atomic --dry-run built the index and reported the split correctly, so the two paths disagreed about the same plan.

The index is now built for dry runs too; the non-atomic preview labels each issue import/update and returns wouldUpdate alongside wouldImport/wouldSkip, matching the atomic shape. Note the coupling: fixing (2) makes dry runs read the tracker, so (1) had to be fixed in the same change or previews would newly hit ENOBUFS.

Verification (same real workspace that exposed the bugs)

command	before	after
pm github import unbraind/pm-cli --state open --dry-run	Would import 29, skip 0	Would import 24, update 5, skip 0
… --dry-run --atomic	Error: pm list-all failed (ENOBUFS)	wouldImport 24, wouldUpdate 5, wouldSkip 0

Both paths now agree exactly. The 5 updates are real: 5 upstream issues in that workspace already carry gh:unbraind/pm-cli#N provenance tags, and a real run would update rather than duplicate them — which the old preview could not tell you.

168/168 tests pass, including two new tests: one asserting the non-atomic preview labels an already-linked issue as an update, one asserting the atomic and non-atomic previews agree on the split.

pm items

item	status
pm-github-tn92 — Import dies with an unexplained pm list-all failed on any tracker over 1 MiB, and non-atomic --dry-run previews every issue as a create	closed

Related fleet context: the same unguarded-maxBuffer pattern exists in 7 sibling packages (pm-beads, pm-jira, pm-todos, pm-starter, pm-gantt-chart, pm-ts-starter, and one call in pm-csv); those are tracked separately.

🤖 Generated with Claude Code

---

Summary by cubic

Raise the pm read buffer to 64 MiB (overridable via PM_JSON_MAX_BUFFER) and fix non-atomic --dry-run so previews correctly show imports vs updates. The cap is resolved per call and rejects malformed overrides, removing unexplained pm list-all failed errors and making dry-run output match real plans.

• Bug Fixes
  • Apply the cap to readPmItems, central pmRun, and afterCommand pm show; resolve it per call. Support PM_JSON_MAX_BUFFER, ignoring invalid values (e.g. "64MiB"); ENOBUFS now reports the effective limit with tips to narrow via --labels/--since.
  • Non-atomic --dry-run builds the provenance index, labels each issue import/update, logs "Would import X, update Y, skip Z", and returns wouldUpdate; tests verify the split and parity with --atomic --dry-run.

^{Written for commit 9d2070b. Summary will update on new commits.}

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Run ID: 0d95174f-993c-406b-a933-3db9e8d0b12b

📥 Commits

Reviewing files that changed from the base of the PR and between ca23a7d and 9d2070b.

📒 Files selected for processing (5)

• .agents/pm/history/pm-github-tn92.jsonl
• .agents/pm/issues/pm-github-tn92.toon
• CHANGELOG.md
• index.ts
• test/dryrun-preview.test.ts

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@unbraind, I’ll perform a complete review of PR #13, including the buffer-limit handling and dry-run preview behavior.

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[unbraind]

Bot-feedback triage — round 1

CodeRabbit — check SUCCESS, no findings. Extra context so a re-review can be sharper: this is a one-constant change with a measured failure behind it, not a defensive tweak. The exact argv this package uses returns over 1 MiB (or within 6% of it) against a real 443-item pm workspace, and past Node's default spawnSync cap the child is killed with status: null, signal: SIGTERM, error.code: ENOBUFS and empty stderr — so the pre-existing if (result.status !== 0) throw result.stderr || "...failed" reported an unexplained failure. At larger sizes stdout truncates mid-JSON (forcing a 100 KiB cap on the same workspace yields Unterminated string in JSON at position 130829). The highest-value thing to look for here is any other unguarded child-process read of pm output in this package that the audit's grep missed.

Sourcery — weekly 500k diff-character rate limit, no review performed; downvote is on the limit notice only, not on Sourcery's judgment.

Gemini — sunset notice, no review; downvoted as non-actionable.

cubic — no findings surfaced.

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🧩 Analysis chain

🏁 Script executed:

#!/bin/bash
set -euo pipefail

printf '%s\n' '== Changed files =='
git diff --name-status "$(git merge-base HEAD origin/main)" HEAD || git diff --name-status HEAD~1 HEAD

printf '%s\n' '== Candidate package/source files =='
fd -t f -E node_modules -E dist -E build | sed -n '1,240p'

printf '%s\n' '== Child-process imports and invocations =='
rg -n -i -C 4 \
  '(from\s+["'\''](?:node:)?child_process["'\'']|require\(["'\''](?:node:)?child_process["'\'']\)|\b(?:spawnSync|execSync|execFileSync|spawn|exec|execFile)\s*\()' \
  -g '!node_modules/**' -g '!dist/**' -g '!build/**' .

printf '%s\n' '== pm command construction / output reads =='
rg -n -i -C 4 \
  '(\bpm\s+(?:list-all|show|[a-z-]+)|["'\'']pm["'\'']|\.stdout\b|JSON\.parse\s*\()' \
  -g '!node_modules/**' -g '!dist/**' -g '!build/**' .

Length of output: 179718

---

🏁 Script executed:

#!/bin/bash
set -euo pipefail

base="$(git merge-base HEAD origin/main 2>/dev/null || git rev-parse HEAD~1)"

printf '%s\n' '== PR diff: index.ts and dry-run tests =='
git diff --unified=80 "$base" HEAD -- index.ts test/dryrun-preview.test.ts

printf '%s\n' '== Import-flow symbols =='
ast-grep outline index.ts --items all --type function --match 'runImport|readPmItems|runAtomicImport|pmRun'

printf '%s\n' '== Import execution and result paths =='
rg -n -C 24 \
  '(shouldMatchExisting|opts\.dryRun|wouldImport|wouldUpdate|wouldSkip|indexByProvenance|readPmItems\(|runAtomicImport\()' \
  index.ts test/dryrun-preview.test.ts

printf '%s\n' '== All production spawnSync call sites with surrounding source =='
rg -n -C 10 '\bspawnSync\s*\(' index.ts scripts/prepare-merge-driver.mjs

Length of output: 87916

---

@unbraind Full re-review complete — no findings.

Focused audit results:

• All production pm output reads are now guarded by the shared 64 MiB buffer: readPmItems(), pmRun(), and the afterCommand pm show hook.
• The remaining child-process uses either invoke gh, inherit stdio (pm merge install), or are test-only fixture helpers; no additional runtime pm reader was missed.
• Non-atomic dry runs now build the provenance index, report per-item import/update, return wouldUpdate, and match the atomic preview split. The new tests cover both the linked-item regression and atomic/non-atomic parity.

I did not execute the test suite because repository code execution is unavailable in this review sandbox.

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[unbraind]

Force-pushed: rebased onto main after #12 merged. The only conflict was CHANGELOG.md, which is generated by pm-changelog from the pm tracker — resolved by regenerating rather than hand-picking hunks, so the result is exactly what npm run changelog:full produces. changelog:check and 168/168 tests green on the new head.

Also carried in from the Greptile round on the sibling packages in this sweep (same code shape, same defects):

• the read cap is now env-overridable (PM_JSON_MAX_BUFFER, in bytes) and resolved per call, so the ENOBUFS message's advice is actually followable — it previously named a module-private compile-time constant;
• the override is parsed with Number() + Number.isSafeInteger, not parseInt: parseInt("64MiB") returns 64, which would have imposed a 64-byte cap and broken every read while appearing to honor the documented invalid-value fallback.

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