Stabilize master CI across platforms

packages/support/acp-snapshot/src/harness.ts

@@ -17,7 +17,7 @@
  */
 
 import { cp, mkdtemp, readFile, readdir, rm } from 'node:fs/promises'
-import { existsSync } from 'node:fs'
+import { existsSync, realpathSync } from 'node:fs'
 import { createHash } from 'node:crypto'
 import { tmpdir } from 'node:os'
 import { basename, dirname, join, delimiter } from 'node:path'
@@ -141,6 +141,8 @@ export interface RunResult {
   sessionId?: string
   /** The generated cwd the session ran in (the bash workspace). */
   cwd: string
+  /** Filesystem-resolved spellings of {@link cwd} that child processes may report. */
+  cwdAliases: string[]
   /**
    * Every persisted session log harvested after the run, ordered primary-first:
    * the top-level (parent) session — the one with no `parentSession` — then each
@@ -222,6 +224,7 @@ export function snapshotSpillRoot(
  */
 export async function runScenario(input: InputScript, opts: RunOptions): Promise<RunResult> {
   const cwd = await mkdtemp(join(opts.workspaceParent ?? tmpdir(), 'acp-snap-cwd-'))
+  const cwdAliases = [...new Set([realpathSync(cwd), realpathSync.native(cwd)])]
   const sessionsRoot = await mkdtemp(join(tmpdir(), 'acp-snap-sessions-'))
   // Fixed path length: spill-policy budgets the preview against the REAL path
   // before stdout normalization, so tmpdir() length differences churn expected outputs.
@@ -329,6 +332,7 @@ export async function runScenario(input: InputScript, opts: RunOptions): Promise
       rawStdout: launched.rawStdout(),
       stderr: launched.stderr(),
       cwd,
+      cwdAliases,
       ...sessionId !== undefined ? { sessionId } : {},
       sessionLogs,
     }

packages/support/acp-snapshot/src/normalize.ts

@@ -46,6 +46,8 @@ export interface NormalizeContext {
   sessionIds: string[]
   /** The generated cwd the run used — replaced with `{{cwd}}`. */
   cwd: string
+  /** Other filesystem spellings of the same cwd (for example Windows short and long paths). */
+  cwdAliases?: readonly string[]
 }
 
 /** How cwd-rooted path separators are represented after the cwd is tokenized. */
@@ -60,9 +62,13 @@ export interface NormalizeOptions {
 /** Replace cwd, session ids, and any stray UUID with stable tokens in a string. */
 function scrubString(value: string, ctx: NormalizeContext, cwdPathMode: CwdPathMode): string {
   let out = value
-  // cwd first (longest, most specific), then explicit session ids, then any
-  // residual UUID (covers ids that appear in places we didn't enumerate).
-  out = out.split(ctx.cwd).join(CWD)
+  // Filesystem APIs can report one directory with several spellings. Replace
+  // every known spelling longest-first so a shorter alias cannot corrupt a
+  // longer one before it is tokenized.
+  const cwdSpellings = [...new Set([ctx.cwd, ...ctx.cwdAliases ?? []])]
+    .filter(spelling => spelling.length > 0)
+    .sort((left, right) => right.length - left.length)
+  for (const spelling of cwdSpellings) out = out.split(spelling).join(CWD)
   out = out.split(`/private${CWD}`).join(CWD)
   if (cwdPathMode === 'canonical') {
     // Restrict separator conversion to paths rooted at the cwd token. A global

packages/support/acp-snapshot/src/suite.ts

@@ -629,6 +629,7 @@ export function defineAcpSnapshotSuite(options: SnapshotSuiteOptions): void {
             ...result.sessionLogs.map(l => l.id),
           ],
           cwd: result.cwd,
+          cwdAliases: result.cwdAliases,
         }
 
         // Record writes live model fixtures; keyless refresh writes every comparable replayed