# Epic resolution — explore response noise (CG-24) Worked 2026-08-05 → 2026-08-06. Started from one bad `codegraph_explore` response in a real session and ended with four shipped fixes, one open defect, and five issues closed because measurement contradicted them. **The headline: the reported symptom was not an explore bug.** It was a degraded index. The explore defects the investigation found are real and were fixed, but none of them caused the report. ## The report A prose flow query returned an unusable response: the symbol the agent had named never rendered, and a 12k-line generated Cloudflare ambient-types file took 60.7% of the output envelope. ``` # deliv% bytes reserved score pen flags file 1 1.0% 251 10,970 87.0 1.00 named entry central 2 60.7% 15,043 6,484 49.0 1.00 entry central worker-configuration.d.ts 4 — — — 19.9 1.00 dropped: budget ``` ## Root cause **Index drift ([CG-33](index-drift-cg33.md)).** The live incrementally-synced index diverged from a clean rebuild by 4.3% of distinct edges, bidirectionally, overwhelmingly `calls`. RWR graph mass is relative and normalized, so call edges missing elsewhere inflate an unaffected file's share — the `.d.ts` carried mass 0.24750 drifted vs 0.13119 rebuilt (~1.9×), score 49.0 vs 27.0. Two causes, both fixed: incremental sync re-resolved only references *in* changed files, and `getNodesByName` had no `ORDER BY`, so ties broke by rowid — i.e. by the order files happened to be **written**. The second is why scope alone could never converge. Stale edges dropped 671 → 2 across an 80-commit replay. On a freshly rebuilt index the reported query answers correctly **with no explore change at all**. ## Shipped | | what | |---|---| | **CG-30** | Bounded how far an oversize cluster member may overshoot; windows on whole lines past 1.5× instead of emitting whole — or, when larger than the response ceiling, dropping the file silently. | | **CG-31** | Gave the cluster path the `owedBelow` displacement guard the whole-file BUY arm always had, holding back only the prefix of what is owed below that the response can actually pay. | | **CG-26** | Closed the remaining holes: whole-file arms had no displacement guard at all, section overhead was charged at a flat 200 against a real 300–500, and `owedPayableBelow` held all-or-nothing. | | **CG-25** | Recognize `Generated by by running ` banners. Precision held by requiring two `by` clauses, so ordinary prose does not match. | | **CG-28** | Damp declaration-only files that nothing in the index depends on. Does not stack with the generated penalty (`Math.min`), and naming a declaration symbol exempts its file. | | **CG-33 / CG-35** | Incremental sync converges with a rebuild, plus a regression suite that fails when the fix is disabled. | | **CG-36** | A later cluster is shrunk into the remainder rather than dropped whole — at selection, and again in the ceiling trim. All 8 starvation flags across the suite clear; +1,012 source chars net. `explore-cluster-starvation-cg36.md`. | Deterministic across the 6-repo suite: no repo truncates, none loses a file, okhttp gains one, every repo lands at or under the 25,000 hard ceiling. ## Follow-up — CG-38 (closed) **Agent-named symbols in the tail of a large file never rendered.** On the motivating repo, `queueMessage` (line 1087) and `flushQueuedMessages` (1102) in a 1,414-line file were absent from the response on both prose and symbol-bag queries, even when that file won rank #1 with 67% of the envelope. The response returned the `QueuedMessage` *interface* at line 70 — a fuzzy near-match on the query token — instead of the function. **Pre-existing, not caused by this epic.** A controlled bisect (index held fixed, engine varied across every merge point) shows the pre-epic engine rendering 12 lines here and CG-36 rendering 463; the symbols render at neither. The epic strictly improves the case. An earlier claim that the epic regressed it was wrong — it compared runs across two different indexes. Two independent causes, both longstanding: `buildFlowFromNamedSymbols` discarded the named-symbol IDENTITY along with the narrative whenever the named symbols did not form a call chain, so the importance-9 injection never ran; and the ceiling trim cut in SOURCE order, so a named def at the end of a large file was always the first thing dropped. Full account, plus the ranker-penalty lead (real, and orthogonal — the defs are absent at both `generated` flag states on the old build and present at both on the new one): `explore-tail-render-cg38.md`. This epic's probes measure envelope share, starvation, source totals and file counts. **None measured "did the agent-named symbol render"** — which is why this survived the whole epic. `scripts/agent-eval/probe-named-symbol.mjs`, `__tests__/fixtures/tail-render-ts` and `__tests__/explore-named-symbol-render.test.ts` close that gap: per-symbol and binary, checking the definition LINE against the response's rendered lines. CG-36's own measurement is worth carrying forward, because the issue named the wrong fix point: both real cases (`query.py`, `RealInterceptorChain.kt`) lost on `maxImportance`, **not** on the density tiebreak the issue suspected. Ranking was left alone; the never-shrink rule was the lever. Full numbers and the one cost (okhttp trades its rank-6 file for +7,196 chars in the two that answer the question) in `explore-cluster-starvation-cg36.md`. ## Closed because measurement contradicted them Five, which is the story of this epic as much as the fixes are. | | why | |---|---| | **CG-32** | Named file "didn't render first." Drift artifact; on a clean index it renders first and takes 89%. | | **CG-34** | "Allocator over-reserves for low-scoring files." Filed on a runner's diagnosis without checking the numbers. The file was never over-reserved (4,314 in both arms) — it was over-*spending*, which is CG-31. | | **CG-27** | Adding `function`/`method` to `ENVELOPE_KINDS` measured as a **large regression** — rank #1 fell from 7,539 delivered chars to 397, 7 of 11 inner closures to 0. The enclosing range was holding the file together as one cluster, inside which `shrinkCluster` already did the per-symbol ranking the issue wanted. A careful version was noise (69 vs 68 across nine queries). | | **CG-29** | Prose-vs-symbol query gap. Inverted on measurement: prose matches symbol on django and delivers 63% more source on okhttp. The founding observation was drift. | | **CG-37** | Duplicate of CG-36, filed without seeing it. | ## What this epic is actually a lesson in **A confident diagnosis is worth less than a cheap measurement.** Every issue above was filed by someone — human or agent — who had read the code and had a plausible mechanism. Five were wrong. The ones that survived did so because a deterministic probe disagreed with them and the probe won. Two specific traps this cost real time on, both now guarded in tooling: - **`.codegraph/graph.db` does not exist** — the index is `codegraph.db`, and `sqlite3` against a mistyped path *creates* an empty database rather than failing. An empty schema reads exactly like a stale pre-migration index. This produced a wrong root cause. `diff-index-drift.mjs` refuses a missing path. - **`ab-new-vs-baseline.sh` checks the engine out at the baseline ref mid-run.** A commit made while it runs captures baseline sources and silently reverts the fix under test. This happened during CG-30. Check the `changed:` line before believing any A/B result. And one measurement discipline worth keeping: **compare sets, not totals.** The drift that started all of this shows up as +0.7% on raw edge counts, because it is bidirectional and nets out. On distinct edge triples it is 4.3%.