fix(session-analysis): recognize lowercase edit tool names from Pi sessions

[chenzier]

Why

Pi's coding agent emits lowercase tool names (edit, write), but edit-event detection in episode-contract.mjs and insights.mjs matched Claude Code's capitalized names (Edit, Write) with a case-sensitive Set lookup:

const EDIT_TOOL_NAMES = new Set(["Edit", "MultiEdit", "NotebookEdit", "Write"]);
// ...
return targetPaths.length > 0 && EDIT_TOOL_NAMES.has(event?.toolName);  // "edit" never matches

Every Pi edit event was therefore missed, which surfaces as withChanges: 0 in session facts for any Pi workspace that demonstrably has commits — meaning Task-Episode change evidence, change-gap classification, and read-only-work correction are all broken for the pi platform.

Notably, the same function already lowercases its input for PATHLESS_EDIT_TOOL_NAMES (apply_patch), so case-insensitive matching is the established intent here; the main set just never got the same treatment.

What changed

• scripts/session-analysis/episode-contract.mjs: EDIT_TOOL_NAMES entries stored lowercase; isEditEvent compares against String(toolName ?? "").toLowerCase()
• scripts/session-analysis/insights.mjs: same fix for its local EDIT_TOOL_NAMES copy, plus null-safe tool-name access

No behavior change for capitalized providers: "Edit".toLowerCase() still matches, and the match set strictly grows.

Validation

Reran session-analysis facts --platform pi over a 254-session workspace before/after:

metric	before	after
populationCoverage.withChanges	0	29
candidate class change-gap	0	11
candidate class read-only-work	44	21
candidateEpisodes	47	53

The workspace had ~500 commits in the analyzed window, so withChanges: 0 was provably a detection failure, not a read-only window.

Backward compatibility: the existing session-episode-contract and lifecycle-demand-signals tests (28 tests, all using capitalized Claude tool names) pass unchanged, and a spot check against a real Claude session (Write tool calls) confirms isEditEvent still returns true for capitalized names while Bash/Read stay false.